CN117996215B - Battery, preparation method thereof and electricity utilization device - Google Patents

Abstract

The application relates to a battery, a preparation method thereof and an electric device, wherein the preparation method of the battery comprises the following steps: drying the battery without liquid injection, sequentially carrying out primary liquid injection and primary formation treatment, and preparing a battery after pre-formation; performing secondary liquid injection on the battery after the pre-formation, and performing secondary formation treatment until the battery reaches a preset charge state to prepare the battery; the method comprises the steps of charging a battery subjected to primary liquid injection to a first charge state at a first multiplying power constant current, and then charging the battery to a second charge state at a second multiplying power constant current; wherein the first magnification is smaller than the second magnification; the first state of charge is less than a second state of charge, which is less than the predetermined state of charge. According to the method, even if no extra high-temperature standing step is carried out after one-time liquid injection, the battery with excellent electrical performance can be prepared, the preparation time is shortened, and the preparation efficiency is improved.

Description

Battery and preparation method thereof, and power-using device

Technical Field

The present invention relates to the technical field of batteries, and in particular to a battery and a preparation method thereof, and an electrical device.

Background Art

In recent years, secondary batteries such as lithium-ion batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields.

Formation is an important process in the production of lithium-ion batteries and other secondary batteries. It is mainly formed by charging, using the current to activate the internal positive and negative electrode materials, or forming an SEI film on the surface of the negative electrode, making the battery performance more stable, thereby achieving the purpose of improving the electrical performance, safety performance, and cycle performance of the secondary battery. However, in the traditional battery preparation process, it is often necessary to stand at high temperature for a long time before charging and formation. The process flow is complicated and the cycle is long. The self-discharge of the battery after formation varies greatly, which reduces the efficiency of the secondary battery production process and consumes a lot of energy.

Therefore, the traditional technology needs to be further improved.

Summary of the invention

Based on this, the present application provides a battery and a preparation method thereof, and an electrical device. The preparation method of the battery can improve the preparation efficiency while ensuring that the battery has good electrical performance.

The present application is implemented through the following technical solutions.

In a first aspect of the present application, a method for preparing a battery is provided, comprising the following steps:

After drying the unfilled battery, a liquid filling and a formation treatment are sequentially performed to prepare a pre-formed battery;

The pre-formed battery is subjected to secondary liquid injection and then subjected to secondary formation treatment to a predetermined state of charge to prepare a battery;

Wherein, the primary formation treatment comprises the following steps:

The battery after the first injection is charged at a first rate constant current to a first state of charge, and then charged at a second rate constant current to a second state of charge; the first state of charge is less than the second state of charge, and the second state of charge is less than the predetermined state of charge;

After the first injection step and before the first formation treatment step, the following steps are also included:

The battery after the primary injection is left to stand at 20°C to 30°C for 1 min to 5 min;

The second state of charge is: 15% SOC~19% SOC.

In the preparation process of the above-mentioned battery, the battery after the drying treatment is injected once. The battery after the drying treatment still retains a certain amount of residual heat. The residual heat can promote the infiltration of the electrolyte into the pole piece, which is beneficial to the subsequent formation. The battery after the first injection is then subjected to a formation treatment under specific conditions, wherein the battery is first charged to the first state of charge at a first rate constant current, and then charged to the second state of charge at a second rate constant current, and the first rate is controlled to be less than the second rate. The battery is first charged at a smaller rate to fully activate the battery active material to promote the formation of the SEI film, and then charged at a larger rate to further promote the complete film-forming reaction of the electrolyte between the pole pieces, improve the SEI film, and reduce lithium precipitation, and then inject liquid and perform secondary formation treatment. In this way, even if no additional high-temperature standing step is performed after the first injection, a battery with excellent electrical performance can be obtained, which shortens the preparation time and improves the preparation efficiency.

In some embodiments, the first ratio is 0.02C~0.1C.

In some embodiments, the first ratio is 0.04C-0.08C.

The first rate is further regulated to further shorten the charging time and reduce the probability of increased polarization due to higher rate charging.

In the process of preparing the battery, if certain conditions do not meet the requirements, such as when the water content exceeds the standard, the self-discharge curve of the battery will be abnormal, that is, the voltage will suddenly decrease or increase. Therefore, this characteristic can be used to detect abnormal defective products in the preparation process. However, if the degree of polarization is large during the preparation process, it will cause the battery to have an abnormal self-discharge curve, that is, the charging condition with a large rate causes the actual electrode potential tested to deviate from the equilibrium electrode potential, and the instantaneously measured voltage deviates from the actual voltage. Therefore, when using the degree of self-discharge change to detect defective products, excessive polarization will interfere with the results, resulting in a decrease in the accuracy of the screening results. In the preparation process of the above-mentioned battery, a small rate of charging is first used, and the degree of polarization is small, that is, the influence of polarization on the subsequent detection of defective batteries using the degree of battery self-discharge change can be reduced, which is conducive to the detection of abnormal batteries.

In some embodiments, the second ratio is 0.33C~1C.

The second rate can be further adjusted to further shorten the charging time and reduce the probability of lithium deposition or black spots in weak areas of the battery (such as thinned areas or corners of the electrode).

In some embodiments, the preparation method satisfies at least one of the following conditions (1) to (2):

(1) The first state of charge is less than or equal to 2% SOC;

(2) The predetermined state of charge is greater than or equal to 60% SOC.

Further control the terminal state of the first state of charge or the second state of charge, that is, first charge at a smaller rate to a specific terminal state of charge to fully activate the battery active materials to promote the formation of the SEI film, and then charge at a larger rate to a specific terminal state of charge to further promote the complete film formation reaction of the electrolyte between the electrodes, improve the SEI film and reduce lithium plating.

In some embodiments, the first state of charge is: 1% SOC~2% SOC.

In some embodiments, the steps of the secondary formation treatment are as follows:

The battery after the secondary injection is charged at a constant current of 0.33C-1C to the predetermined state of charge.

In some embodiments, the preparation method satisfies at least one of the following conditions (1) to (2):

(1) After the step of charging to a first state of charge at a first rate constant current and before the step of charging at a second rate constant current, the following steps are also included:

The battery charged to the first state of charge at a first rate constant current is left to stand at 20° C. to 30° C. for 3 min to 10 min;

(2) After the primary chemical treatment step and before the secondary liquid injection step, the following steps are also included:

The pre-formed battery is allowed to stand at 20° C. to 30° C. for 1 min to 5 min.

In some embodiments, the method for preparing the battery satisfies at least one of the following conditions (1) to (2):

(1) The temperature of the primary chemical treatment is 25° C. to 45° C.;

Regulating the temperature of the primary formation treatment is beneficial to the formation of the SEI film.

(2) The primary chemical formation treatment is carried out under a negative pressure environment.

Gases are inevitably produced as by-products during the formation process, and a negative pressure environment is conducive to exhaust.

In some embodiments, the relative pressure of the negative pressure environment is -20Kpa ~-0.2Kpa.

In some embodiments, the method for preparing the battery satisfies at least one of the following conditions (1) to (2):

(1) The electrolyte used in the primary liquid injection treatment contains a film-forming agent;

In the primary formation treatment, the formation of SEI film is mainly promoted. Adding film-forming agent to the electrolyte used in this process is beneficial to the formation and improvement of SEI film.

(2) Based on the total mass of the electrolyte used in the first injection treatment and the electrolyte used in the second injection treatment, the mass of the electrolyte used in the first injection treatment accounts for 80% to 90%.

In some embodiments, the drying temperature is 95°C to 115°C.

The battery still retains a certain amount of residual heat after drying. When the electrolyte is directly injected, the residual heat can promote the infiltration of the electrolyte into the electrode, which is beneficial to the subsequent formation.

In some of the embodiments, after the secondary formation step, the method further includes performing an aging treatment on the battery after the secondary formation step.

In some embodiments, the aging treatment is carried out at a temperature of 45°C±5°C and for a time of 48 h±2 h.

The second aspect of the present application provides a method for preparing the battery of the first aspect, comprising the following steps:

According to a third aspect of the present application, there is provided an electrical device, wherein the electrical device comprises the battery according to the first aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings:

FIG1 is a flow chart of a battery preparation process in one embodiment;

FIG. 2 is a schematic diagram of an embodiment of a battery cell in an embodiment;

Fig. 3 is an exploded view of Fig. 2;

FIG4 is a schematic diagram of an embodiment of a battery pack;

FIG5 is an exploded view of FIG4;

FIG. 6 is a schematic diagram of an embodiment of an electric device using a battery as a power source.

Description of reference numerals:

1. Battery pack; 2. Upper box; 3. Lower box; 4. Battery cell; 41. Shell; 42. Electrode assembly; 5. Electrical device.

DETAILED DESCRIPTION

In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and/or" used herein includes any and all combinations of one or more of the related listed items.

In this application, unless otherwise specified, "room temperature" generally refers to 10°C to 30°C, preferably 20°C ± 5°C.

An embodiment of the present application provides a method for preparing a battery, comprising the following steps S10 to S20.

Step S10: After drying the unfilled battery, a liquid filling and a formation treatment are performed in sequence to prepare a pre-formed battery.

Step S20: The pre-formed battery is subjected to secondary liquid injection and then subjected to secondary formation treatment to a predetermined state of charge to prepare the battery.

Among them, the primary chemical treatment includes the following steps:

The battery after the first injection is charged at a first rate constant current to a first state of charge, and then charged at a second rate constant current to a second state of charge.

The first rate is smaller than the second rate; the first state of charge is smaller than the second state of charge, and the second state of charge is smaller than a predetermined state of charge.

In the preparation process of the above-mentioned battery, the battery after the drying treatment is injected once. The battery after the drying treatment still retains a certain amount of residual heat. The residual heat can promote the infiltration of the electrolyte into the pole piece, which is beneficial to the subsequent formation. The battery after the first injection is then subjected to a formation treatment under specific conditions, wherein the battery is first charged to the first state of charge at a first rate constant current, and then charged to the second state of charge at a second rate constant current, and the first rate is controlled to be less than the second rate. The battery is first charged at a smaller rate to fully activate the battery active material to promote the formation of the SEI film, and then charged at a larger rate to further promote the complete film-forming reaction of the electrolyte between the pole pieces, improve the SEI film, and reduce lithium precipitation, and then inject liquid and perform secondary formation treatment. In this way, even if no additional high-temperature standing step is performed after the first injection, a battery with excellent electrical performance can be obtained, which shortens the preparation time and improves the preparation efficiency.

In some embodiments, the battery after drying is directly injected with liquid.

Please refer to FIG. 1 for details. FIG. 1 is a flow chart of a battery preparation process in one embodiment, which specifically includes the following steps performed in sequence:

Step S11: Dry the unfilled battery.

Step S12: one injection.

Step S13: primary formation treatment: charging the battery after the primary injection at a first rate constant current to a first state of charge, and then charging it at a second rate constant current to a second state of charge, to prepare a pre-formed battery.

Step S21: performing secondary liquid injection on the pre-formed battery.

Step S22: secondary formation treatment to a predetermined state of charge.

In some embodiments, the first magnification is 0.02C-0.1C.

In some embodiments, the first ratio is 0.04C-0.08C.

The first rate is further regulated to further shorten the charging time and reduce the probability of increased polarization due to higher rate charging.

In the process of preparing the battery, if certain conditions do not meet the requirements, such as when the water content exceeds the standard, the self-discharge curve of the battery will be abnormal, that is, the voltage will suddenly decrease or increase. Therefore, this characteristic can be used to detect abnormal defective products in the preparation process. However, if the degree of polarization is large during the preparation process, it will cause the battery to have an abnormal self-discharge curve, that is, the charging condition with a large rate causes the actual electrode potential tested to deviate from the equilibrium electrode potential, and the instantaneously measured voltage deviates from the actual voltage. Therefore, when using the degree of self-discharge change to detect defective products, excessive polarization will interfere with the results, resulting in a decrease in the accuracy of the screening results. In the preparation process of the above-mentioned battery, a small rate of charging is first used, and the degree of polarization is small, that is, the influence of polarization on the subsequent detection of defective batteries using the degree of battery self-discharge change can be reduced, which is conducive to the detection of abnormal batteries.

It should be noted that the size of the charge and discharge current is usually expressed in charge and discharge rates, and the letter ‘C’ represents the charge and discharge rate of the battery. The charge and discharge rate refers to the current value required for the battery to discharge the rated capacity within a specified time. It is equal to the multiple of the rated capacity of the battery in the data value and is usually represented by the letter C. For example: for a 24AH battery, the discharge current at 2C is 48A, and the discharge voltage at 0.5C is 12A.

Different battery systems have different specific values of 1C. Generally, the charge and discharge rate = charge and discharge current/rated capacity; for example, when a battery with a rated capacity of 100Ah is discharged at 20A, its discharge rate is 0.2C.

In the above "0.02C~0.1C", the specific values include the minimum and maximum values of the range, and every value between the minimum and maximum values. Specific examples include but are not limited to the point values in the embodiments and the following point values: 0.02C, 0.03C, 0.04C, 0.05C, 0.06C, 0.07C, 0.08C, 0.09C, 0.1C; or a range consisting of any two values.

In some embodiments, the second ratio is 0.33C~1C.

In the above "0.33C~1C", the specific values include the minimum and maximum values of the range, and every value between the minimum and maximum values. Specific examples include but are not limited to the point values in the embodiments and the following point values: 0.33C, 0.4C, 0.45C, 0.5C, 0.55C, 0.6C, 0.65C, 0.7C, 0.75C, 0.8C, 0.85C, 0.9C, 0.95C, 1C; or a range consisting of any two values.

The second rate can be further adjusted to further shorten the charging time and reduce the probability of lithium deposition or black spots in weak areas of the battery (such as thinned areas or corners of the electrode).

In some of these embodiments, the first state of charge is less than or equal to 2% SOC.

In some embodiments, the first state of charge is: 1% SOC~2% SOC.

In some of these embodiments, the second state of charge is less than or equal to 25% SOC.

In some embodiments, the first state of charge is 15% SOC~25% SOC.

In some of these embodiments, the second state of charge is less than or equal to 20% SOC.

In some embodiments, the second state of charge is: 15% SOC~20% SOC.

In some of these embodiments, the predetermined state of charge is greater than or equal to 60% SOC.

Further control the terminal state of the first state of charge or the second state of charge, that is, first charge at a smaller rate to a specific terminal state of charge to fully activate the battery active materials to promote the formation of the SEI film, and then charge at a larger rate to a specific terminal state of charge to further promote the complete film formation reaction of the electrolyte between the electrodes, improve the SEI film and reduce lithium plating.

In the above "1% SOC~2% SOC", the specific values include the minimum and maximum values of the range, and every value between the minimum and maximum values. Specific examples include but are not limited to the point values in the embodiments and the following point values: 1% SOC, 1.1% SOC, 1.2% SOC, 1.3% SOC, 1.4% SOC, 1.5% SOC, 1.6% SOC, 1.7% SOC, 1.8% SOC, 1.9% SOC, 2% SOC; or a range consisting of any two values.

In the above-mentioned "15% SOC~25% SOC", the specific values include the minimum and maximum values of the range, and every value between the minimum and maximum values. Specific examples include but are not limited to the point values in the embodiments and the following point values: 15% SOC, 15.5% SOC, 16% SOC, 15.5% SOC, 17% SOC, 17.5% SOC, 18% SOC, 18.5% SOC, 19% SOC, 19.5% SOC, 20% SOC, 20.5% SOC, 21% SOC, 21.5% SOC, 22% SOC, 22.5% SOC, 23% SOC, 23.5% SOC, 24% SOC, 24.5% SOC, 25% SOC; or a range consisting of any two values.

In some embodiments, the steps of the secondary formation process are as follows:

The battery after secondary injection is charged at a constant current of 0.33C~1C to a predetermined state of charge.

In some embodiments, the predetermined state of charge is: 60% SOC~70% SOC.

In some embodiments, the temperature of the primary chemical formation treatment is 25°C-45°C.

Regulating the temperature of the primary formation treatment is beneficial to the formation of the SEI film.

In some embodiments, the primary formation treatment is performed under negative pressure.

Gases are inevitably produced as by-products during the formation process, and a negative pressure environment is conducive to exhaust.

In some of the embodiments, the relative pressure of the negative pressure environment is -20 Kpa~-0.2 Kpa.

It can be understood that relative pressure refers to the difference between actual pressure and atmospheric pressure, which can be directly tested using a pressure gauge.

After the first injection step and before the first formation treatment step, the following steps are also included:

The battery after the primary injection is allowed to stand at 20°C to 30°C for 1min to 5min. Further, the standing step is performed under negative pressure, and the relative pressure of the negative pressure environment is -20Kpa to -0.2Kpa.

After the step of charging to a first state of charge at a first rate constant current and before the step of charging at a second rate constant current, the following steps are also included:

The battery charged to the first state of charge at a first rate constant current is allowed to stand for 3 min to 10 min at 20° C. to 30° C. Further, the standing step is performed under negative pressure, and the relative pressure of the negative pressure environment is -20 Kpa to -0.2 Kpa.

In some embodiments, after the primary chemical treatment step and before the secondary liquid injection step, the following steps are also included:

The pre-formed battery is allowed to stand at 20° C. to 30° C. for 1 min to 5 min. Further, the standing step is performed under negative pressure.

In some of the embodiments, based on the total mass of the electrolyte used in the first injection treatment and the electrolyte used in the second injection treatment, the mass of the electrolyte used in the first injection treatment accounts for 80% to 90%.

In the above "80%~90%", the specific values include the minimum and maximum values of the range, and every value between the minimum and maximum values. Specific examples include but are not limited to the point values in the embodiments and the following point values: 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%; or a range consisting of any two values.

In some embodiments, the drying temperature is 95° C. to 115° C. Further, the temperature of the battery after the drying process is 95° C. to 115° C.

Further controlling the drying temperature, on the one hand, allows the moisture in the battery to fully evaporate, and on the other hand, the battery can retain a certain amount of residual heat after drying. When the electrolyte is directly injected, the residual heat can promote the infiltration of the electrolyte into the electrode, which is beneficial to the subsequent formation.

In some of the embodiments, after the secondary formation step, the method further includes performing an aging treatment on the battery after the secondary formation step.

In some embodiments, the aging treatment is performed at a temperature of 45° C.±5° C. and for a time of 48 h±2 h.

It is understandable that the components of the electrolyte used in the primary injection and the secondary injection may be the same or different, and both may be electrolytes commonly used in the field for secondary batteries.

Here is a brief introduction to the electrolytes commonly used in secondary batteries in the art, including but not limited to the following contents.

The electrolyte solution includes an electrolyte salt and a solvent.

In some embodiments, the electrolyte salt may be selected from electrolyte salts commonly used in the art, such as lithium ion electrolyte salts.

As an example, the lithium ion electrolyte salt includes, but is not limited to, one or more of lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium perchlorate (LiClO ₄ ), lithium hexafluoroarsenate (LiAsF ₆ ), lithium bisfluorosulfonyl imide (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium bisoxalatoborate (LiBOB), lithium difluorophosphate (LiPO ₂ F ₂ ), lithium difluorobisoxalatophosphate (LiDFOP) and lithium tetrafluorooxalatophosphate (LiTFOP).

In some embodiments, the solvent can be selected from one or more of fluoroethylene carbonate (FEC), ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS) and diethyl sulfone (ESE).

In some embodiments, in the electrolyte solution, the concentration of the electrolyte salt is generally 0.5 mol/L to 15 mol/L.

In some embodiments, the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.

In some of the embodiments, the electrolyte used in the primary injection treatment contains a film-forming agent.

In the primary formation treatment, the formation of SEI film is mainly promoted. Adding film-forming agent to the electrolyte used in this process is beneficial to the formation and improvement of SEI film.

The film-forming agent may be a commonly used film-forming agent in the art, including but not limited to at least one of VC (vinylene carbonate) and FEC (fluoroethylene carbonate).

It can be understood that the battery without liquid injection after the drying treatment comprises a battery assembly and a shell covering the battery assembly, and the battery assembly comprises a positive electrode sheet, a negative electrode sheet and a separator disposed between the positive electrode sheet and the negative electrode sheet. Further, the positive electrode sheet, the negative electrode sheet and the separator can be formed into an electrode assembly through a lamination process.

In some of the embodiments, the electrolyte is infiltrated between the electrode components.

The positive electrode sheet, negative electrode sheet and separator can be the commonly used positive electrode sheet, negative electrode sheet and separator in various secondary batteries in the art. The commonly used positive electrode sheet, negative electrode sheet and separator are briefly introduced below, but are not limited to the following contents.

The negative electrode sheet includes a current collector and a negative electrode active layer arranged on the surface of the current collector.

The current collector in the negative electrode sheet has two surfaces opposite to each other in its thickness direction, and the negative electrode active layer is arranged on any one or both of the two opposite surfaces of the current collector; further, the negative electrode active layer is arranged on the two opposite surfaces of the current collector.

In some embodiments, the component of the negative electrode active layer of the negative electrode sheet includes a negative electrode active material.

In some embodiments, the silicon anode material includes at least one of a silicon-oxygen anode material and a silicon-carbon anode material.

It can be understood that the silicon-carbon negative electrode material and the silicon-oxygen negative electrode material can be specifically selected from various common silicon-carbon negative electrode materials and silicon-oxygen negative electrode materials in the art. Here, the commonly used silicon-carbon negative electrode materials and silicon-oxygen negative electrode materials are briefly introduced, but are not limited to the following types.

Silicon-carbon negative electrode material: refers to a composite material of silicon and carbon. The carbon material used includes but is not limited to: at least one of graphite, MCMB, carbon black, carbon nanotubes, and graphene; further, in the silicon-carbon negative electrode material, the mass ratio of silicon to carbon can be any ratio.

In some of the embodiments, according to the composite method, the silicon-carbon negative electrode material is mainly divided into coated type, embedded type and molecular contact type, and according to the morphology, it is divided into particle type and thin film type, and according to the number of silicon-carbon types, it is divided into silicon-carbon binary composite and silicon-carbon multi-composite.

The preparation processes of silicon-carbon composite materials include ball milling, high-temperature cracking, chemical vapor deposition, sputtering deposition, evaporation and so on.

Silicon-oxygen negative electrode material: The molecular formula is SiOx, where x is any value from 0 to 2. Non-limiting examples include silicon dioxide and silicon dioxide.

The above-mentioned carbon negative electrode material can adopt the carbon negative electrode material commonly used in the art, including but not limited to: at least one of mesophase carbon microbeads, natural graphite, artificial graphite, graphene, glassy carbon, carbon nanotubes, carbon fiber, hard carbon, and soft carbon.

In some embodiments, the negative electrode active layer of the negative electrode sheet also includes a conductive agent and a binder.

In some of the embodiments, in the negative electrode active layer, the mass proportion of the negative electrode active material is less than 70% to 99%.

In some of the embodiments, in the negative electrode active layer, the mass proportion of the conductive agent is selected from 1% to 5%.

In some of the embodiments, in the negative electrode active layer, the mass proportion of the binder is selected from 1% to 5%.

The conductive agent can be a conductive material commonly used in the art, including but not limited to at least one of graphite, carbon nanotubes, nanofibers, carbon black and graphene. Specifically, it can be selected from at least one of SP, KS-6, acetylene black, branched Ketjen black ECP, SFG-6, vapor-grown carbon fiber VGCF, carbon nanotubes CNTs and graphene and composite conductive agents thereof.

The above-mentioned binder can be a binder commonly used in the art, and can be selected from at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, hydrogenated nitrile rubber, styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), carboxymethyl chitosan (CMCS) and fluorine-containing acrylate resin.

In some embodiments, the current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material on a polymer material substrate.

In some embodiments, the metal material includes at least one of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy.

In some of the embodiments, the polymer material substrate includes at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

In some embodiments, the positive electrode sheet includes a current collector and a positive electrode active layer disposed on a surface of the current collector.

It should be noted that the current collector of the positive electrode sheet has two surfaces opposite to each other in the direction of its own thickness, and the positive electrode active material layer or the negative electrode active layer is arranged on any one or both of the two opposite surfaces of the current collector. In the technical solution of the present application, the positive electrode active layer is provided on both surfaces opposite to each other in the direction of its own thickness in the positive electrode sheet.

In any embodiment of the present application, the current collector in the positive electrode sheet may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material on a polymer material substrate.

In some embodiments, the metal material includes at least one of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy.

In some of the embodiments, the polymer material substrate includes at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

The components of the positive electrode active layer include a positive electrode active material.

The positive electrode active material may be a commonly used positive electrode active material in the present application, such as a lithium ion positive electrode active material or a sodium ion positive electrode active material.

Further, as an example, the lithium ion active material may include at least one of the following materials: an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO ₂ ), lithium nickel oxide (such as LiNiO ₂ ), lithium manganese oxide (such as LiMnO ₂ , LiMn ₂ O ₄ ), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi _1/3 Co _1/3 Mn _1/3 O ₂ (also referred to as NCM333), LiNi _0.5 Co _0.2 Mn _0.3 O ₂ (also referred to as NCM523), LiNi _0.5 Co _0.25 Mn _0.25 O ₂ (also referred to as NCM211), LiNi _0.6 Co _0.2 Mn _0.2 O ₂ (also referred to as NCM622), LiNi _0.8 Co _0.1 Mn _0.1 O ₂ (also referred to as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi _0.85 Co _0.15 Al _0.05 O ₂ ) and modified compounds thereof. Examples of lithium-containing phosphates with an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO ₄ (also referred to as LFP)), lithium manganese phosphate (such as LiMnPO ₄ ), and lithium manganese iron phosphate.

In any embodiment of the present application, the molecular formula of the lithium ion active material is: LiFe _x Mn _(1-x) PO ₄ , where x is any number from 0 to 1.

It can be understood that when x is 0, LiFe _x Mn _(1-x) PO ₄ is LiMnPO ₄ lithium manganese phosphate, and when x is 1, LiFePO ₄ is LiFePO ₄ lithium iron phosphate (LFP).

It should be noted that the lithium content in the positive electrode material exemplified above refers to its content when it is not in use. During the use of the battery, it will be repeatedly used as a battery, and the Li in the positive electrode active material will change during the charging and discharging process, that is, the molar subscript of Li in the positive electrode active material in the battery product will not always remain at 1, but will change; further, the range of change can be (0~1.2).

For example, LiFe _x Mn _(1-x) PO ₄ can be further expressed as Li _y Fe _x Mn _(1-x) PO ₄ , where y is 0 to 1.1.

For example, for the ternary material Li _y (Ni _a Co _b Mn _c ) _1-d M _d O _2-x A _x , y is 0.2~1.2, a+b+c=1, 0≤d≤1, 0≤x<2; M is one or more of Zr, Sr, B, Ti, Mg, Sn and Al, and A is one or more of S, N, F, Cl, Br and I.

The battery will be accompanied by Li deintercalation and consumption during the charge and discharge process. The molar content of Li is different when the battery is discharged to different states. The above definition of y includes the molar content of Li under different charge and discharge states of the battery; further, the battery voltage is usually between 2-5V.

Similarly, in the list of positive electrode materials in this application, the oxygen (O) content is only a theoretical state value. The release of oxygen from the lattice will cause the molar content of oxygen to change, and the actual content of O will fluctuate. Among them, the content of O can be measured by molar content, but is not limited to this.

As an example, the sodium ion active material may include at least one of the following materials: at least one of a sodium transition metal oxide, a polyanionic compound, and a Prussian blue compound. However, the present application is not limited to these materials, and other conventionally known materials that can be used as positive electrode active materials for sodium ion batteries may also be used.

As an optional technical solution of the present application, in the sodium transition metal oxide, the transition metal includes at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce. The sodium transition metal oxide is, for example, Na _x MO ₂ , wherein M includes at least one or more of Ti, V, Mn, Co, Ni, Fe, Cr and Cu, and 0＜x≤1.

As an optional technical solution of the present application, the polyanionic compound can be a class of compounds having sodium ions, transition metal ions and tetrahedral (YO ₄ ) ^n- anion units. The transition metal includes at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce; Y includes at least one of P, S and Si; n represents the valence state of (YO ₄ ) ^n- .

The polyanionic compound may also be a compound having sodium ions, transition metal ions, tetrahedral (YO ₄ ) ^n- anion units and halogen anions. The transition metal includes at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce; Y includes at least one of P, S and Si, and n represents the valence state of (YO ₄ ) ^n- ; the halogen may be at least one of F, Cl and Br.

The polyanionic compound may also be a compound having sodium ions, tetrahedral (YO ₄ ) ^n- anion units, polyhedral units (ZO _y ) ^m+ and optional halogen anions. Y includes at least one of P, S and Si, and n represents the valence state of (YO ₄ ) ^n- ; Z represents a transition metal, including at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce, and m represents the valence state of (ZO _y ) ^m+ ; the halogen may be at least one of F, Cl and Br.

The polyanionic compound is, for example, at least one of NaFePO ₄ , Na ₃ V ₂ (PO ₄ ) ₃ (sodium vanadium phosphate, abbreviated as NVP), Na ₄ Fe ₃ (PO ₄ ) ₂ (P ₂ O ₇ ), NaM'PO ₄ F (M' is one or more of V, Fe, Mn and Ni) and Na ₃ (VO _y ) ₂ (PO ₄ ) ₂ F _3-2y (0≤y≤1).

The Prussian blue compound may be a compound having sodium ions, transition metal ions and cyanide ions (CN ^- ). The transition metal includes at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce. The Prussian blue compound is, for example, Na _a Me _b Me' _c (CN) ₆ , wherein Me and Me' each independently include at least one of Ni, Cu, Fe, Mn, Co and Zn, 0＜a≤2, 0＜b＜1, 0＜c＜1.

The weight ratio of the positive electrode active material in the positive electrode active layer is 80% to 100% based on the total weight of the positive electrode active layer.

In any embodiment of the present application, the components of the positive electrode active layer further include a positive electrode conductor and a positive electrode binder.

The positive electrode conductive agent can be a conductive agent commonly used in the art, including but not limited to: at least one of graphite, carbon nanotubes, nanofibers, carbon black and graphene. Specifically, it can be selected from SP, KS-6, acetylene black, branched Ketjen black ECP, SFG-6, vapor-grown carbon fiber VGCF, carbon nanotubes CNTs and graphene and their composite conductive agents.

Based on the total weight of the positive electrode active layer, the weight ratio of the positive electrode conductive agent in the positive electrode active layer is 0-20wt%.

In any embodiment of the present application, the binder of the above-mentioned positive electrode binder can be polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, hydrogenated nitrile rubber, styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), carboxymethyl chitosan (CMCS) and at least one of fluorine-containing acrylate resins.

Based on the total weight of the positive electrode active layer, the weight ratio of the positive electrode binder in the positive electrode active layer is 0-30wt%.

In some embodiments, the compaction density of the positive electrode sheet is 3.0 g/cm ³ to 3.7 g/cm ³ , and can be 3.4 g/cm ³ to 3.6 g/cm ³ . The calculation formula of the compaction density is:

Compacted density = coating surface density/(thickness of electrode after extrusion - thickness of current collector).

The present application has no particular limitation on the type of isolation membrane, and any known porous isolation membrane with good chemical stability and mechanical stability can be selected.

In some embodiments, the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

The thickness of the diaphragm is controlled within a range of 2 μm to 15 μm; optionally, the thickness of the diaphragm is controlled within a range of 2 μm to 13 μm.

In some of the embodiments, the positive electrode sheet or the negative electrode sheet can be prepared by the following method: dispersing the components of the positive electrode active layer or the negative electrode active layer in a solvent to form a slurry; coating the slurry on the current collector, and obtaining the electrode sheet after drying, cold pressing and other processes.

Furthermore, the solvent includes, but is not limited to, N-methylpyrrolidone or water.

The components of the positive electrode active layer or the negative electrode active layer are as mentioned above and will not be described in detail here.

In some of the embodiments, the solid content of the slurry is 40 wt% to 80 wt%, and the viscosity at room temperature is adjusted to 5000 mPa·s to 25000 mPa·s.

The coating method includes but is not limited to printing coating, blade coating, spin coating or inkjet coating. The slurry is coated on the current collector, and after drying, cold pressing and other processes, a coating can be obtained.

In one embodiment of the present application, a battery is further provided. The battery is manufactured using the above-mentioned battery manufacturing method.

In some embodiments, the battery is a secondary battery; specifically, the battery is a lithium-ion battery.

The shape of the battery of the present application is not particularly limited, and it can be a square or any other shape. For example, FIG2 is a battery cell 4 of a square structure as an example.

In some embodiments, referring to FIG3 , the housing may include a shell 41 and a cover plate 43. The shell 41 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate are enclosed to form a receiving cavity. The shell 41 has an opening connected to the receiving cavity, and the cover plate 43 can be covered on the opening to close the receiving cavity.

The positive electrode sheet, the negative electrode sheet and the separator can be wound or laminated to form an electrode assembly 42. The electrode assembly 42 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 42. The number of electrode assemblies 42 contained in the battery cell 4 can be one or more, which can be adjusted according to needs.

The battery includes one or more battery cells 4 .

The battery may be a battery module or a battery pack; the battery module or battery pack includes at least one battery cell. The number of battery cells 4 included in the battery module may be one or more, and those skilled in the art may select a suitable number according to the application and capacity of the battery module.

4 and 5 are battery packs 1 as an example. The battery pack 1 includes a battery box and one or more battery cells 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form a closed space for the battery cells 4.

The plurality of battery cells 4 may be arranged in the battery box in any manner.

The present application also provides an electrical device, which includes the above-mentioned battery.

Furthermore, in the above-mentioned electrical device, the battery may exist in the form of a battery cell, or may be further assembled into a battery pack.

The above-mentioned battery or the battery pack assembled therefrom can be used as a power source for an electrical device, or as an energy storage unit for an electrical device.

The above-mentioned electrical devices may be, but are not limited to, mobile equipment, electric vehicles, electric trains, ships and satellites, energy storage systems, etc.

Mobile devices include but are not limited to: mobile phones, laptops, etc.; electric vehicles include but are not limited to: pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts or electric trucks, etc.

Fig. 6 is an example of an electric device 5. The electric device 5 is a pure electric vehicle, a hybrid electric vehicle or a plug-in hybrid electric vehicle. In order to meet the electric device 5's requirements for high power and high energy density of the battery, a battery pack may be used.

As another example, the power-consuming device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be light and thin, and a battery may be used as a power source.

The present application will be described below in conjunction with specific embodiments, but the present application is not limited to the following embodiments. It should be understood that the attached claims summarize the scope of the present application. Under the guidance of the concept of the present application, technical personnel in the field should realize that certain changes made to the various embodiments of the present application will be covered by the spirit and scope of the claims of the present application.

The following are specific embodiments.

Example 1

(1) Preparation of lithium-ion batteries, comprising the following steps:

The positive electrode sheet, the separator and the negative electrode sheet are wound to obtain an electrode assembly, the electrode assembly is placed in a packaging shell, and the tabs are led out from the electrode assembly to assemble an NCM811 lithium-ion battery with a theoretical capacity of 60Ah without liquid injection, and the charging rate of the battery is 1C=60Ah.

The steps for preparing the negative electrode sheet are as follows:

Graphite, conductive carbon super P, thickener sodium carboxymethyl cellulose, and binder styrene butadiene rubber were mixed in a mass ratio of 96.5:0.7:1.2:1.6, and then water was added. The mixture was mixed and stirred to obtain a negative electrode slurry with a solid content of 50wt%, which was coated on a negative electrode current collector with a thickness of 6μm. The coating unit mass was 0.1636g/ ^1540.25mm2 . After drying, a negative electrode sheet with a thickness of 0.1363mm was obtained by cold pressing at a density of 1.63g/ ^cm3 .

The steps for preparing the positive electrode are as follows:

NCM811, conductive carbon super P, and binder polyvinylidene fluoride were mixed in a mass ratio of 96.5:2.3:1.2, N-methylpyrrolidone was added, and the mixture was stirred to obtain a positive electrode slurry with a solid content of 50wt%, which was coated on a positive electrode current collector with a thickness of 13μm. The coating unit mass was 0.280g/ ^1540.25mm2 . After drying, the mixture was cold pressed at a density of 3.4g/ ^cm3 to obtain a positive electrode sheet with a thickness of 0.1190mm.

Isolation membrane: A PE (polyethylene) membrane with a thickness of 7 μm is used, and a ceramic layer with a thickness of 1 μm is coated on both sides of the membrane to obtain an isolation membrane. The ceramic layer is formed by coating and drying a ceramic slurry with a solid content of 40wt%. The preparation steps of the ceramic slurry are as follows:

Boehmite, binder styrene-butadiene rubber, and thickener were mixed in a mass ratio of 96:2:2, and water was added, and the mixture was mixed and stirred to form a ceramic slurry with a solid content of 40 wt%.

(2) The NCM811 lithium-ion battery assembled in step (1) is placed in a baking furnace at a temperature of 100°C for drying treatment. When the weight loss rate of the battery reaches the standard, the battery is injected once within 2 hours, and the injection amount reaches 85% of the theoretical total injection amount. Then, it is immediately placed in a negative pressure formation device with a relative pressure of -20Kpa and a temperature of 25°C. After standing for 1 minute, a formation treatment is performed: charging at a first rate (0.1C) constant current to a first state of charge (2% SOC), then standing for 5 minutes, charging at a second rate (0.5C) constant current to a second state of charge (20% SOC), and then standing for 5 minutes, releasing the vacuum to end the first formation treatment; then continue to inject the remaining 15% electrolyte, and then perform a secondary formation treatment: charging at a charging rate of 0.5C to a predetermined state of charge (70% SOC) of the battery capacity, and then placing the battery in a high-temperature furnace at 45°C for aging treatment for 48 hours to obtain a battery.

In the above preparation process, the time from the start of the first injection to the start of the high-temperature aging treatment was recorded, denoted as H. The specific results are shown in Table 1.

The preparation of the electrolyte used for the primary injection and the secondary injection is as follows:

The components of the electrolyte include: lithium salt lithium hexafluorophosphate, film-forming additive vinylene carbonate VC, film-forming additive vinyl sulfate DTD, solvent vinyl carbonate EC and solvent dimethyl carbonate DMC in a mass ratio of 15:1:1:13:70.

(3) Testing:

1. Place the battery after aging treatment at room temperature (25°C), test and record the self-discharge change value T within 48 hours at room temperature. The specific steps are as follows:

After the aging treatment, place the battery at room temperature (25°C) for 12 hours, and record the battery voltage OCV1; then continue to place it at room temperature for 48 hours, and record OCV2; the voltage unit is mV; T = (OCV1-OCV2)/48; the unit of T is mV/h. Please see Table 1 for specific results.

2. Interface of the negative electrode of the battery:

The battery after the high temperature treatment is fully charged, and the specific steps are as follows:

The battery after the high temperature treatment is placed in a charging and discharging machine with the temperature set at room temperature (25°C). After the battery temperature drops to room temperature, the battery is first discharged to 2.8V at a rate of 0.5C, left for 5 minutes, and then charged to 4.25V at a rate of 0.5C. Then, it is charged at a constant voltage of 4.25V until the rate drops to 0.05C.

Then disassemble the negative electrode sheet, confirm the interface condition of the negative electrode sheet, and observe whether there are decomposition and black spots. Please see Table 1 for specific results.

3. Yield test:

Repeat steps (1) to (3) to obtain 100 batches of batteries. If there is no decomposition or black spots on the interface of the negative electrode and the self-discharge change value T is ≤ 0.02mV/h, the battery is judged to be good and the good rate is calculated:

Yield rate = number of good products / total number of batteries × %

Please see Table 1 for specific results.

Embodiments 2 to 8

Examples 2 to 8 are basically the same as Example 1, except that in step (2), at least one parameter control of the first rate, the second rate, the first state of charge or the second state of charge is different from that of Example 1. For specific parameters and test results, please see Table 1.

The other step conditions are the same as those in Example 1.

Comparative Example 1

Comparative Example 1 is substantially the same as Example 1, except that the specific steps of step (2) are as follows:

(2): The NCM811 lithium-ion battery assembled in step (1) is placed in a baking furnace at a temperature of 100°C for drying treatment. When the weight loss rate of the battery reaches the standard, the battery is injected once within 2 hours, and the injection amount reaches 85% of the theoretical total injection amount. Then, it is immediately placed in a negative pressure formation device with a relative pressure of -20Kpa and a temperature of 25°C. After standing for 1 minute, a formation treatment is performed: charging at a first rate (0.1C) constant current to a first state of charge (2% SOC), then standing for 5 minutes, charging at a second rate (0.5C) constant current to a second state of charge (70% SOC), and then standing for 5 minutes, releasing the vacuum, and ending the formation treatment; then continue to inject the remaining 15% electrolyte, and then place the battery in a high-temperature furnace at 45°C for aging treatment for 48 hours to obtain a battery.

The other step conditions are the same as those in Example 1. Please see Table 1 for specific parameters and test results.

Comparative Example 2

Comparative Example 2 is substantially the same as Example 1, except that the steps of step (2) are as follows:

(2) The NCM811 lithium-ion battery assembled in step (1) is placed in a baking furnace at a temperature of 100° C. for drying treatment. When the weight loss rate of the battery reaches the standard, the battery is injected once within 2 hours, and the injection amount reaches 85% of the theoretical total injection amount. Then, it is immediately placed in a negative pressure formation device with a relative pressure of -20 KPa and a temperature of 25° C., and after standing for 1 minute, a formation treatment is performed: charging at a first rate (0.1C) constant current to a first state of charge (2% SOC), then standing for 5 minutes, charging at a second rate (0.5C) constant current to a second state of charge (20% SOC), and after standing for another 5 minutes, the vacuum is released to end the formation treatment; then the remaining 15% electrolyte is continued to be injected, and the battery is placed in a high-temperature furnace at 45° C. for aging treatment for 48 hours to obtain a battery.

The other step conditions are the same as those in Example 1. Please see Table 1 for specific parameters and test results.

Comparative Example 3

Comparative Example 3 is substantially the same as Example 1, except that the steps of step (2) are as follows:

(2) The NCM811 lithium-ion battery assembled in step (1) is placed in a baking furnace at a temperature of 100° C. for drying treatment. When the weight loss rate of the battery reaches the standard, the battery is injected once within 2 hours, and the injection amount reaches 85% of the theoretical total injection amount. Then, it is placed in a 45° C. high-temperature furnace for high-temperature static treatment for 10 hours, and then immediately placed in a negative pressure formation device with a relative pressure of -20 KPa and a temperature of 25° C., and after standing for 1 minute, a formation treatment is performed: charging at a first rate (0.1C) constant current to a first state of charge (2% SOC), then standing for 5 minutes, and then charging at a second rate (0.5C) constant current to a second state of charge (70% SOC), and after standing for another 5 minutes, the vacuum is released to end the formation treatment; then the remaining 15% electrolyte is continued to be injected, and the battery is placed in a 45° C. high-temperature furnace for static aging treatment for 48 hours to obtain a battery.

The other step conditions are the same as those in Example 1. Please see Table 1 for specific parameters and test results.

Comparative Example 4

Comparative Example 4 is substantially the same as Example 1, except that the steps of step (2) are as follows:

(2) The NCM811 lithium-ion battery assembled in step (1) is placed in a baking furnace at a temperature of 100° C. for drying treatment. When the weight loss rate of the battery reaches the standard, the battery is injected once within 2 hours, and the injection amount reaches 85% of the theoretical total injection amount. Then, it is immediately placed in a negative pressure formation device with a relative pressure of -20 KPa and a temperature of 25° C., and after standing for 1 minute, a formation treatment is performed: charging at a first rate (0.5C) constant current to a first state of charge (2% SOC), then standing for 5 minutes, charging at a second rate (0.1C) constant current to a second state of charge (20% SOC), and after standing for another 5 minutes, the vacuum is released to end the first formation treatment; then the remaining 15% electrolyte is continued to be injected, and a secondary formation treatment is performed: charging at a charging rate of 0.5C to a predetermined state of charge (70% SOC) of the battery capacity, and then the battery is placed in a high-temperature furnace at 45° C. for aging treatment for 48 hours to obtain a battery.

The parameters and test results of each embodiment and comparative example are shown in Table 1. The first state of charge is recorded as X%, and the second state of charge is recorded as Y%.

Table 1

Note: “/” means no change step is performed or no change parameter exists.

Analysis of the data in Table 1: By comparing the data of Examples 1 to 8 and Comparative Examples 1 to 4, it can be seen that: by adopting the technical solution of the present application, a battery with perfect performance can be produced even without an additional high-temperature standing step after a single injection, thereby shortening the preparation time and improving the preparation efficiency.

Among them, by comparing and analyzing Example 1, Comparative Example 1 and Comparative Example 3, it can be known that: directly forming to a higher SOC state after liquid injection, it may be due to insufficient electrolyte infiltration, and the interface of the negative electrode sheet after full charge has black spots and lithium precipitation (such as Comparative Example 1). It is necessary to add an additional longer high-temperature standing time after liquid injection to ensure that the full charge interface after forming to a high SOC is good (such as Comparative Example 3). If the subsequent high SOC charging is cancelled, not only will there be black spots and lithium precipitation on the interface of the negative electrode sheet after full charge, but also because the 20% SOC stage corresponds to the large slope area of the charging curve, the voltage change in this detection unit time is too large, which is not conducive to screening samples with poor self-discharge (such as Comparative Example 2); as in Comparative Example 4, a large rate charging is used at the beginning of formation, which will lead to insufficient infiltration and serious adverse phenomena at the interface of the electrode sheet.

The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims, and the description and drawings may be used to interpret the contents of the claims.

Claims (16)

1. A method of making a battery comprising the steps of:

drying the battery without liquid injection, and then directly and sequentially carrying out primary liquid injection and primary formation treatment to prepare a battery after pre-formation; the temperature of the drying treatment is 95-115 ℃;

Performing secondary liquid injection on the battery after the pre-formation, and performing secondary formation treatment until the battery reaches a preset charge state to prepare the battery;

Wherein, the primary formation treatment comprises the following steps:

The battery after the primary liquid injection is charged to a first charge state with a constant current of a first multiplying power, and then is charged to a second charge state with a constant current of a second multiplying power;

Wherein the first state of charge is less than the second state of charge, the second state of charge being less than the predetermined state of charge; the first multiplying power is 0.02-0.1C, and the second multiplying power is 0.33-1C;

after the step of injecting liquid once and before the step of forming treatment once, the method further comprises the following steps:

standing the battery subjected to primary liquid injection at 20-30 ℃ for 1-5 min;

the second charge state is 15-19% of SOC.

2. The method for manufacturing a battery according to claim 1, wherein the first rate is 0.04c to 0.08c.

3. The method of making a battery of claim 1, wherein the first state of charge is less than or equal to 2% SOC.

4. The method for manufacturing a battery according to any one of claims 1 to 3, wherein the predetermined state of charge is greater than or equal to 60% SOC.

5. The method for preparing a battery according to any one of claims 1 to 3, wherein the first state of charge is: 1% SOC to 2% SOC.

6. A method of manufacturing a battery according to any one of claims 1 to 3, wherein the secondary formation treatment comprises the steps of:

and charging the battery subjected to secondary liquid injection to the preset charge state at a constant current of 0.33-1 ℃.

7. The method for manufacturing a battery according to any one of claims 1 to 3, further comprising, after the step of constant-current charging at the first rate to the first state of charge and before the step of constant-current charging at the second rate, the steps of:

And standing the battery charged to the first charge state at the first multiplying power constant current at 20-30 ℃ for 3-10 min.

8. The method for manufacturing a battery according to any one of claims 1 to 3, further comprising, after the step of the primary formation treatment and before the step of the secondary injection, the steps of:

And standing the battery subjected to the pre-formation for 1-5 min at 20-30 ℃.

9. The method for manufacturing a battery according to any one of claims 1 to 3, wherein the method for manufacturing a battery satisfies at least one of the following conditions (1) to (2):

(1) The temperature of the primary formation treatment is 25-45 ℃;

(2) The primary formation treatment is carried out in a negative pressure environment.

10. The method of claim 9, wherein the relative pressure of the negative pressure environment is-20 Kpa to-0.2 Kpa.

11. The method for manufacturing a battery according to any one of claim 1 to 3, wherein,

The electrolyte adopted in the primary liquid injection treatment contains a film forming agent.

12. The method for producing a battery according to any one of claims 1 to 3, wherein the mass ratio of the electrolyte used in the primary liquid injection treatment is 80% to 90% based on the total mass of the electrolyte used in the primary liquid injection treatment and the electrolyte used in the secondary liquid injection treatment.

13. The method for manufacturing a battery according to any one of claims 1 to 3, further comprising the step of aging the battery after the secondary formation treatment after the step of the secondary formation treatment.

14. The method for manufacturing a battery according to claim 13, wherein the aging treatment is performed at a temperature of 45 ℃ ± 5 ℃ for a time of 48h ± 2h.

15. A battery prepared by the method for preparing a battery according to any one of claims 1 to 14.

16. An electric device is characterized in that, the power utilization device includes the battery of claim 15.