WO2021057306A1 - Additive for battery, secondary battery, battery module, battery pack, and apparatus - Google Patents

Abstract

An additive for a battery, a secondary battery (5), a battery module (4), a battery pack (1), and an apparatus. The additive comprises a core structure and a cladding layer with which the core structure is cladded. The core structure comprises one or more of an aniline compound and a pyrrole compound. The melting point of the cladding layer falls within a range of 80-150°C.

Description

Additives for batteries, secondary batteries, battery modules, battery packs and devices

Cross-references to related applications

This application claims the priority of the Chinese patent application 201910917642.0 filed on September 26, 2019, entitled "Additives for batteries, secondary batteries, battery modules, battery packs and devices", the entire contents of which are incorporated by reference Incorporated into this article.

Technical field

This application relates to the field of energy storage materials, in particular to a battery additive, a secondary battery, a battery module, a battery pack and a device.

Background technique

Compared with lead-acid batteries, nickel-metal hydride batteries, and nickel-cadmium batteries, secondary batteries have the advantages of high specific energy density, high discharge rate and long cycle life, and have been widely used in consumer electronics and power energy storage fields. The safety performance of secondary batteries is widely concerned by customers.

When the battery heats up during the cycle, it may cause thermal runaway of the battery, which may cause the battery to burn or explode.

Summary of the invention

The first aspect of the present application provides an additive for a battery. The additive for a battery includes a core structure and a coating layer covering the core structure, wherein the core structure includes one of an aniline compound and a pyrrole compound. One or more kinds, the melting point of the coating layer is 80°C-150°C.

In the battery additive according to the first aspect described above, the pyrrole compound is selected from one or more of the compounds represented by formula (I),

Wherein R1 to R5 are each independently selected from a hydrogen atom, an amino group, a sulfonic acid group, a halogen atom, a substituted or unsubstituted C ₁ -C ₂₀ alkyl group, a substituted or unsubstituted C ₂ -C ₂₀ alkenyl group, a substituted or unsubstituted Substituted C ₆ -C ₂₆ aryl, substituted or unsubstituted C ₁ -C ₂₀ alkylsulfonyl, substituted or unsubstituted C ₂ -C ₂₀ alkenyl sulfonyl, substituted or unsubstituted C ₆ -C ₂₆ The arylsulfonyl group; and wherein the substituent is selected from a halogen atom, an amino group or a C ₁ -C ₄ alkyl group.

In any battery additive according to the above-mentioned first aspect, the pyrrole compound is selected from the group consisting of pyrrole, 1-phenylpyrrole, 3-acetylpyrrole, 2,4-dimethyl-3-acetylpyrrole, 3- Aminopyrrole, 1-(3-bromopropyl)pyrrole, 1-(4-fluorophenyl)pyrrole, 1-(4-iodophenyl)pyrrole, 3-methylpyrrole, 3-ethylpyrrole, 3- N-propylpyrrole, 3-butylpyrrole, 3-octylpyrrole, 3-decylpyrrole, 3-dodecylpyrrole, 3,4-dimethylpyrrole, 3,4-dibutylpyrrole, 3 -Methoxypyrrole, 3-ethoxypyrrole, 3-butoxypyrrole, 3-hexoxypyrrole, 3-methyl-4-hexoxypyrrole, 3-methyl-4-hexoxypyrrole One or more of 1-(2-aminophenyl)pyrrole and tosylpyrrole; optionally, the pyrrole compound is selected from one or more of pyrrole and 3-methylpyrrole.

In any battery additive according to the above first aspect, the aniline compound is selected from the group consisting of aniline, 2-naphthylamine, 2-hydroxyaniline, p-hydroxyaniline, p-nitroaniline, o-aminoaniline, 1,3-benzene Diamine, diphenylamine, 2,4-dichloroaniline, 3,4-dichloroaniline, 2,4-difluoroaniline, 3,5-dichloroaniline, 3,4-dimethoxyaniline, 3- Hydroxy-N,N-dimethylaniline, 4-bromo-N,N-dimethylaniline, 2-methoxy-5-methylaniline, 3-methoxy-5-methylaniline, p-chloro One or more of aniline, p-bromoaniline, meta-bromoaniline, o-bromoaniline, and o-toluidine; optionally, the aniline compound is selected from one or more of 2-naphthylamine and diphenylamine .

In any battery additive according to the first aspect described above, the coating layer includes polyvinyl chloride, polyethylene, ethylene-vinyl acetate, ethylene acrylic acid copolymer, chlorinated polyethylene, polyolefin elastomer POE, natural rubber , Butadiene rubber, polyisoprene, ethylene propylene rubber, styrene butadiene rubber; optionally, the coating layer includes one or more of polyethylene, ethylene-vinyl acetate Kind.

In any battery additive according to the first aspect described above, the weight ratio of the core structure to the coating layer is 30:1-10:1, optionally 25:1-15:1, or 23:1 1～16:1, such as 20:1.

In any battery additive according to the first aspect described above, the average thickness of the coating layer is 10 μm to 30 μm, optionally 10 μm to 20 μm.

The second aspect of the present application provides a secondary battery including the battery additive described in the first aspect of the present application.

The secondary battery according to the second aspect described above includes an outer packaging body and a battery cell and an electrolyte contained in the outer packaging body, the battery cell including a positive pole piece, a negative pole piece, and a separator, wherein the outer packaging body, At least one of the electrolyte, the positive pole piece, the negative pole piece, and the separator includes the battery additive according to the first aspect of the present application.

In any secondary battery according to the second aspect described above, at least one of the outer package and the electrolyte includes the battery additive according to the first aspect of the present application.

In any secondary battery according to the above second aspect, the added amount of the battery additive accounts for 1% to 5% of the total weight of the electrolyte, optionally 1.5% to 3.5%.

In some embodiments of the second aspect of the present application, the secondary battery can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.

In some embodiments of the second aspect of the present application, the above-mentioned battery modules can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

The third aspect of the present application provides a device including at least one of the secondary battery, battery module, or battery pack according to the second aspect of the present application, and the secondary battery, battery module, or battery pack can be used As the power source of the device, it can also be used as the energy storage unit of the device.

This application includes at least the following beneficial effects:

The battery additive of the present application includes a core structure and a coating layer covering the core structure. Both the core material and the coating material meet specific conditions. When the battery is used under normal conditions, the additive will not affect the battery performance. Have an impact; when the battery is used in a high temperature environment, the coating layer on the surface of the additive will melt first, and then the core structure will be released into the electrolyte to form a micro short circuit inside the battery; it can make the battery's remaining power (SOC) in a short time Effectively reduce, so as to ensure that the battery does not have thermal runaway at high temperatures, and ensure the safety performance of the battery.

definition

When used herein, unless otherwise specified, "a", "this", "at least one", and "one or more" and situations where quantifiers are not used can be used interchangeably. Unless otherwise stated herein, the use of the singular form in this document is also intended to include the plural form.

In the description herein, it should be noted that, unless otherwise specified, "above" and "below" include the number, and the meaning of "several" in "one or more" means two or more than two.

Where the composition is described as including or containing specific components, optional components not covered in this application are not excluded from the composition, and the composition may be composed or composed of the involved components, or in the method Where it is described as including or containing specific process steps, the method does not exclude optional process steps that are not involved in this application, and the method can be constituted or composed of the involved process steps.

For brevity, only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, and any upper limit can be combined with any other upper limit to form an unspecified range. In addition, each individually disclosed point or single value can be used as a lower limit or upper limit in combination with any other point or single value or with other lower or upper limits to form an unspecified range.

In the context of this application, when the material used to form the coating layer is crystalline or semi-crystalline, the "melting point" refers to the measurement by differential scanning calorimetry according to ISO 11357-1/3 (2009) When the material used to form the coating layer is amorphous, the "melting point" refers to the Vicat heat distortion temperature measured according to GB/T 1633-2000.

In the context of this application, the term SOC (State of Charge) represents the remaining power, that is, the ratio of the remaining capacity of the battery after a period of time or long-term use of the battery to its fully charged state, expressed as a percentage. The value range of the remaining power SOC is 0 to 1. When SOC=0, the battery is fully discharged, and when SOC=1, the battery is fully charged.

The terms "optional" and "optionally" refer to embodiments of the present application that can provide certain benefits under certain circumstances. However, under the same or other circumstances, other implementations may also be optional. In addition, the description of one or more optional embodiments does not mean that other embodiments are unavailable, and is not intended to exclude other embodiments from the scope of this application.

Description of the drawings

Fig. 1 is a schematic diagram of an embodiment of a secondary battery.

Fig. 2 is an exploded view of Fig. 1.

Fig. 3 is a schematic diagram of an embodiment of a battery module.

Fig. 4 is a schematic diagram of an embodiment of a battery pack.

Fig. 5 is an exploded view of Fig. 4.

Fig. 6 is a schematic diagram of an embodiment of a device in which a secondary battery is used as a power source.

detailed description

The electrolyte and battery according to the present application will be described in detail below.

Electrolyte

The first aspect of the present application provides an additive for a battery. The additive for a battery includes a core structure and a coating layer covering the core structure, wherein the core structure includes an aniline compound and a pyrrole compound. One or more, the melting point of the coating layer is 80°C-150°C.

The structure of this additive can be called a core-shell structure or a capsule.

The coating layer is usually a polymer coating layer (melting point 80°C-150°C), optionally a non-conductive polymer coating layer (melting point 80°C-150°C). In an optional embodiment according to the present application, the coating layer is selected from polyvinyl chloride, polyethylene, ethylene-vinyl acetate, ethylene acrylic acid copolymer, chlorinated polyethylene, polyolefin elastomer POE, natural rubber, One or more of butadiene rubber, polyisoprene, ethylene-propylene rubber, and styrene-butadiene rubber; more optionally, the coating layer is selected from one of polyethylene, ethylene-vinyl acetate, or Several kinds.

In an optional embodiment according to the present application, the pyrrole compound is selected from one or more of the compounds represented by formula (I),

Wherein R1 to R5 are each independently selected from a hydrogen atom, an amino group, a sulfonic acid group, a halogen atom, a substituted or unsubstituted C ₁ -C ₂₀ alkyl group, a substituted or unsubstituted C ₁ -C ₂₀ alkoxy group, a substituted or Unsubstituted C ₂ -C ₂₀ alkenyl, substituted or unsubstituted C ₆ -C ₂₆ aryl, substituted or unsubstituted C ₁ -C ₂₀ alkylsulfonyl, substituted or unsubstituted C ₂ -C ₂₀ alkene A sulfonyl group, a substituted or unsubstituted C ₆ -C ₂₆ arylsulfonyl group; wherein the substituent is selected from a halogen atom, an amino group or a C ₁ -C ₄ alkyl group.

The C ₁ -C ₂₀ alkyl group can be a chain alkyl group or a cyclic alkyl group. The chain alkyl group can be a straight chain alkyl group or a branched chain alkyl group. The hydrogen on the ring of the cyclic alkyl group is reduced It may be further substituted by a substituent. The _{optional lower limit of the number of carbon atoms in the C 1} -C ₂₀ alkyl group is 1, 2, 3, 4, and 5, and the optional upper limit is 3, 4, 5, 6, 8, 10, 12. Optionally, a C ₁ -C ₁₂ alkyl group is selected. Examples of C ₁ -C ₁₂ alkyl groups include: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, Isopentyl, neopentyl, hexyl, octyl, nonyl, decyl, dodecyl.

When R1 to R5 are each independently selected from substituted or unsubstituted C ₁ -C ₁₂ alkoxy, optionally, C ₁ -C ₁₀ alkoxy is selected; further alternatively, C ₁ -C ₆ alkane is selected Oxy; further optionally, a C ₁ -C ₄ alkoxy group is selected. As _{examples of C 1} -C ₁₂ alkoxy groups, specific examples include: methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, N-pentyloxy, isopentyloxy, cyclopentyloxy, cyclohexyloxy.

The C ₂ -C ₂₀ alkenyl group may be a cyclic alkenyl group or a chain alkenyl group, and the chain alkenyl group may be a straight chain alkenyl group or a branched chain alkenyl group. In addition, the number of double bonds in the _{C 2} -C _{20 alkenyl group may be one.} The _{optional lower limit of the number of carbon atoms in the C 2} -C ₂₀ alkenyl group is 2, 3, 4, and 5, and the optional upper limit is 3, 4, 5, 6, 8, 10, 12. Optionally, a C ₂ -C ₁₀ alkenyl group is selected; further alternatively, a C ₂ -C ₆ alkenyl group is selected; still further optionally, a C ₂ -C ₅ alkenyl group is selected. Specific examples of the C ₂ -C ₂₀ alkenyl group include vinyl, allyl, isopropenyl, pentenyl, cyclohexenyl, cycloheptenyl, and cyclooctenyl.

The C ₆ -C ₂₆ aryl group can be a phenyl group, a phenalkyl group, a biphenyl group, a fused ring aromatic hydrocarbon group (such as naphthyl, anthryl, phenanthryl), and the biphenyl group and a fused ring aromatic hydrocarbon group can be further alkylated Or alkenyl substitution. The optional lower limit of the number of carbon atoms in the C 6 -C ₂₆ aryl group is 6, 7, and 8, and the optional upper limit is 12, 15, _{16, 17, 18, 19, and 20.} Optionally, a C ₆ -C ₁₆ aryl group is selected; further alternatively, a C ₆ -C ₁₄ aryl group is selected; still further optionally, a C ₆ -C ₉ aryl group is selected. Specific examples of C ₆ -C ₂₆ aryl groups include phenyl, benzyl, biphenyl, p-tolyl, o-tolyl, m-tolyl, naphthyl, anthryl, and phenanthryl.

Examples of C ₁ -C ₂₀ alkylsulfonyl groups include, but are not limited to, methylsulfonyl, ethylsulfonyl, and propylsulfonyl; _{examples of C 6} -C ₂₀ arylsulfonyl groups include, but are not limited to, phenylsulfonyl, Tosyl.

The halogen atom includes fluorine atom, chlorine atom, bromine atom and iodine atom.

Specifically, suitable pyrrole compounds include, but are not limited to, pyrrole, 1-phenylpyrrole, 3-acetylpyrrole, 2,4-dimethyl-3-acetylpyrrole, 3-aminopyrrole, 1-(3 -Bromopropyl)pyrrole, 1-(4-fluorophenyl)pyrrole, 1-(4-iodophenyl)pyrrole, 3-methylpyrrole, 3-ethylpyrrole, 3-n-propylpyrrole, 3- Butylpyrrole, 3-octylpyrrole, 3-decylpyrrole, 3-dodecylpyrrole, 3,4-dimethylpyrrole, 3,4-dibutylpyrrole, 3-methoxypyrrole, 3 -Ethoxypyrrole, 3-butoxypyrrole, 3-hexyloxypyrrole, 3-methyl-4-hexyloxypyrrole, 3-methyl-4-hexyloxypyrrole, 1-(2-amino Phenyl) pyrrole and tosylpyrrole; optionally, the pyrrole compound includes one or more of pyrrole and 3-methylpyrrole.

Suitable aniline compounds include but are not limited to: aniline, 2-naphthylamine, 2-hydroxyaniline, p-hydroxyaniline, p-nitroaniline, o-aminoaniline, 1,3-phenylenediamine, diphenylamine, 2,4- Dichloroaniline, 3,4-dichloroaniline, 2,4-difluoroaniline, 3,5-dichloroaniline, 3,4-dimethoxyaniline, 3-hydroxy-N,N-dimethylaniline , 4-Bromo-N,N-dimethylaniline, 2-methoxy-5-methylaniline, 3-methoxy-5-methylaniline, p-chloroaniline, p-bromoaniline, m-bromoaniline, One or more of o-bromoaniline and o-toluidine; optionally, the aniline compound includes one or more of 2-naphthylamine and diphenylamine.

Those skilled in the art can understand that, if necessary, in addition to the aniline compound and/or pyrrole compound, the core structure may also contain a small amount of additives or auxiliary agents. In some embodiments, the core structure consists essentially of the aniline compound and/or pyrrole compound.

The inventor of the present application found that by selecting a specific core structure and coating layer, and using the coating layer to coat the core structure, the following effect can be achieved: When the battery is in the normal temperature range, the core structure is coated in the coating In the layer, it will not affect the normal use of the battery; as the heat of the battery increases, when the temperature reaches 80-150°C, the coating layer begins to melt gradually, releasing the core structure into the electrolyte of the battery. At this time, the core structure is electro-oxidized and polymerized in the electrolyte, and a p-type doped conductive polymer bridge is formed between the positive and negative electrodes as the polymerization product deposits and grows, thereby connecting the positive and negative electrodes, resulting in a battery The internal micro short circuit can effectively reduce the battery's remaining power (SOC) in a short time, so as to ensure that the battery does not have thermal runaway at high temperatures and ensure the safety performance of the battery.

Although there are reports in the related art about the use of aniline compounds or pyrrole compounds as electrolyte additives, they are generally used directly without coating, and the role of such additives is often when the charging voltage reaches the oxidation of the additive. At the potential, the additive will undergo in-situ oxidative coupling reaction, thereby forming a conductive polymer network on the positive electrode of the lithium ion secondary battery, and the conductive polymer network formed thereby can effectively improve the conductivity of the battery's positive electrode active material (Usually a conductive polymer network is formed during the first charge or the formation step of battery manufacturing). It can be seen that this is obviously different from the effect of aniline compounds or pyrrole compounds in this application.

The coating layer for coating the core structure can be formed by any suitable method known in the art. Optionally, the coating layer adopts one or more methods selected from the group consisting of melt extrusion method, melt blending method, phase separation method, spray drying method, electrospinning method, in-situ polymerization method, and interfacial polymerization method. form.

In order to achieve effective coating, the weight ratio of the core structure to the coating layer is 30:1-10:1, optionally 25:1-15:1, or 23:1-16:1, such as 20:1 .

The core structure is covered with a coating layer, and the core structure is released into the electrolyte after the coating layer is gradually melted at a temperature of 80°C-150°C. Therefore, the thickness of the coating layer will affect the release efficiency of the core structure. If the thickness of the coating layer is too large, the release rate of the core structure will be too slow; and if the thickness of the coating layer is too small, the core structure may be released in advance, thereby affecting the normal use of the battery. Therefore, in some embodiments according to the present application, the average thickness of the coating layer may be 10 μm to 30 μm, and may be 10 μm to 20 μm.

Secondary battery

The secondary battery according to the second aspect of the present application will be described below.

The secondary battery of the second aspect of the present application includes an outer package and a battery cell and electrolyte contained in the outer package. The battery cell includes a positive pole piece, a negative pole piece and a separator. It is understandable that any position that can be in contact with the electrolyte in the battery can include the battery additive of the first aspect of the present application.

Optionally, at least one of the outer packaging body, the electrolyte, the positive pole piece, the negative pole piece, and the separator contains the battery additive of the first aspect of the present application; more optionally, the outer packaging body and the electrolyte At least one of them contains the battery additive of the first aspect of the present application.

Specifically, for example, in the secondary battery of the present application, the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector and including a positive electrode active material, and the positive electrode film layer is also The battery additive of the first aspect of the present application may be included.

The present application has no special restrictions on the composition of the positive electrode active material. The positive electrode active material can be selected from lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium Nickel-cobalt-aluminum oxides, olivine-structured lithium-containing phosphates, etc., but the present application is not limited to these materials, and other conventionally known materials that can be used as positive electrode active materials for secondary batteries can also be used. These positive electrode active materials may be used alone or in combination of two or more. Optionally, the positive electrode active material includes one or more of lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide.

This application has no special restrictions on the composition of the active material of the positive electrode sheet, and the battery additives can be used in conjunction with various positive electrode active materials. However, the advantages of the battery additive according to the present application are more prominent when it is applied to positive pole pieces with high safety requirements. Therefore, the battery additive according to the present application is particularly suitable for positive pole pieces with high safety requirements, such as high nickel content. The meta material is used as the positive pole piece of the positive active material. In the context of this application, "high nickel ternary material" refers to a ternary material whose nickel mole fraction in the material is greater than or equal to 0.5, such as Li _1+x Ni _a Co _b Me _(1-ab) O ₂ , where − 0.1≤x≤0.2, 0.5≤a<1 (optionally, 0.8≤a<1), 0<b<1, Me is selected from Mn, Al, Mg, Zn, Ga, Ba, Fe, Cr, Sn, At least one of V, Sc, Ti, and Zr (optionally Mn or Al). Therefore, in an alternative embodiment of the present application, the positive electrode active material layer contains Li _1+x Ni _a Co _b Me _(1-ab) O ₂ , where -0.1≤x≤0.2, 0.5≤a<1 (may Optionally, 0.8≤a<1), 0<b<1, Me is selected from at least one of Mn, Al, Mg, Zn, Ga, Ba, Fe, Cr, Sn, V, Sc, Ti, Zr ( Optional is Mn or Al). These materials are well known in the art, and their composition and preparation methods are also well known in the art.

The positive electrode film layer may also optionally include a binder and a conductive agent. Among them, the type and content of the binder and the conductive agent are not specifically limited, and can be selected according to actual needs.

The positive electrode current collector can use materials commonly used in the art, such as metal flakes or metal foils such as stainless steel, aluminum, copper, and titanium. Optionally, the positive electrode current collector is aluminum foil.

Specifically, in the secondary battery of the present application, the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector and including a negative electrode active material, and the negative electrode film layer may further include The battery additive of the first aspect of the present application.

The negative active material can be selected from artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and the like. However, this application is not limited to these materials, and other conventionally known materials that can be used as secondary battery negative electrode active materials can also be used. These negative electrode active materials may be used alone or in combination of two or more. Optionally, the negative electrode active material includes one or more of artificial graphite, natural graphite, and silicon-based materials.

The negative electrode film layer may also optionally include a binder and a conductive agent. Among them, the type and content of the binder and the conductive agent are not specifically limited, and can be selected according to actual needs.

The negative electrode current collector can use materials commonly used in the art, such as metal foil or porous metal plate. Optionally, the negative electrode current collector is copper foil.

Specifically, in the secondary battery of the present application, the separation film includes a substrate and a coating. The substrate can be selected from polyethylene, polypropylene, polyvinylidene fluoride and their multilayer composite films, but not limited to these; the coating includes one or more of inorganic particles and polymers, and the coating The layer may also include the battery additive of the first aspect of the present application.

Specifically, in the secondary battery of the present application, the electrolyte includes an electrolyte salt and an organic solvent, and the electrolyte may further include the battery additive of the first aspect of the present application.

The types of the electrolyte salt and the organic solvent are not specifically limited, and can be selected according to actual needs. For example, as the non-aqueous electrolyte, an electrolyte salt solution dissolved in an organic solvent is generally used. The electrolyte salt is, for example, LiClO ₄ , LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiSbF _6, etc., or LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , Li ₂ C ₂ F ₄ (SO ₃ ) ₂ , LiN (CF ₃ SO ₂ ) _2. LiC(CF ₃ SO ₂ ) ₃ , LiC _n F _2n+1 SO ₃ (n≥2), etc. The organic solvent used in the non-aqueous electrolyte is, for example, cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate. And other chain carbonates, chain esters such as methyl propionate, cyclic esters such as γ-butyrolactone, dimethoxyethane, diethyl ether, diglyme, triglyme and other chains Like ethers, cyclic ethers such as tetrahydrofuran and 2-methyltetrahydrofuran, nitriles such as acetonitrile and propionitrile, or mixtures of these solvents. The electrolyte may also include other additives, such as negative electrode film-forming additives, positive electrode film-forming additives, additives for improving battery overcharge performance, additives for improving battery high temperature performance, and additives for improving battery low temperature performance.

Specifically, in the secondary battery of the present application, the outer packaging body may be a soft case or a hard case. The battery additive of the first aspect of the present application can be coated on the position where the outer package can contact the electrolyte.

In the secondary battery of the present application, optionally, based on the total weight of the electrolyte in the battery, the added amount of the additive accounts for 1% to 5% of the total weight of the electrolyte, and optionally 1.5% to 3.5%. When the content of the additive is within the given range, the battery can take into account the advantages of high-temperature safety performance and energy density at the same time.

The present application has no particular limitation on the shape of the secondary battery, which can be cylindrical, square or other arbitrary shapes. Fig. 1 shows a secondary battery 5 with a square structure as an example.

In some embodiments, the secondary battery may include an outer package. The outer packaging is used to encapsulate the positive pole piece, the negative pole piece and the electrolyte.

In some embodiments, referring to FIG. 2, the outer package may include a housing 51 and a cover 53. Wherein, the housing 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose to form an accommodating cavity. The housing 51 has an opening communicating with the containing cavity, and a cover plate 53 can cover the opening to close the containing cavity.

The positive pole piece, the negative pole piece and the separator may be formed into the electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is packaged in the receiving cavity. The electrolyte may be an electrolyte, and the electrolyte is infiltrated in the electrode assembly 52. The number of electrode assemblies 52 included in the secondary battery 5 can be one or several, which can be adjusted according to requirements.

In some embodiments, the outer packaging of the secondary battery may be a hard case, such as a hard plastic case, aluminum case, steel case, or the like. The outer packaging of the secondary battery may also be a soft bag, such as a pouch type soft bag. The material of the soft bag may be plastic, for example, it may include one or more of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), and the like.

In some embodiments, the secondary battery can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.

FIG. 3 is a battery module 4 as an example. Referring to FIG. 3, in the battery module 4, a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4. Of course, it can also be arranged in any other manner. Furthermore, the plurality of secondary batteries 5 can be fixed by fasteners.

Optionally, the battery module 4 may further include a housing having an accommodation space, and a plurality of secondary batteries 5 are accommodated in the accommodation space.

In some embodiments, the above-mentioned battery modules can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

Figures 4 and 5 show the battery pack 1 as an example. 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 provided 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 be covered on the lower box body 3 and forms a closed space for accommodating the battery module 4. A plurality of battery modules 4 can be arranged in the battery box in any manner.

Device

The device of the third aspect of the present application includes at least one of the secondary battery, battery module, or battery pack described in the present application, and the secondary battery, battery module, or battery pack can be used as the device The power supply can also be used as the energy storage unit of the device. The device can be, but is not limited to, mobile devices (such as mobile phones, laptop computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf Vehicles, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

The device can select a secondary battery, a battery module, or a battery pack according to its usage requirements.

Fig. 6 is a device as an example. The device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the requirements of the device for high power and high energy density of secondary batteries, battery packs or battery modules can be used.

As another example, the device may be a mobile phone, a tablet computer, a notebook computer, and the like. The device is generally required to be thin and light, and a secondary battery can be used as a power source.

The above content of this application is not intended to describe each disclosed embodiment or every implementation in this application. The following description more specifically exemplifies exemplary embodiments. In many places throughout the application, guidance is provided through a series of examples, which can be used in various combinations. In each instance, the enumeration serves only as a representative group and should not be interpreted as an exhaustive list.

Example

The following examples more specifically describe the content disclosed in the present application, and these examples are only used for explanatory description, because various modifications and changes within the scope of the present disclosure are obvious to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods, and can be directly obtained. Used without further processing, and the instruments used in the examples are all commercially available.

(1) Preparation of positive pole piece for lithium ion battery

The positive electrode active material lithium nickel cobalt manganate (LiNi _0.8 Co _0.1 Mn _0.1 O ₂ ), the conductive agent Super-P, and the binder polyvinylidene fluoride (PVDF) are dissolved in the solvent N-form at a weight ratio of 96:2:2. NMP is mixed uniformly to make a positive electrode slurry, and then the positive electrode slurry is evenly coated on the aluminum foil of the current collector, and then dried at 85°C, then cold pressing, trimming, cutting, and slitting are performed, and then Dry for 4 hours under vacuum at 85°C, weld the tabs, and make the positive pole piece.

(2) Preparation of negative pole piece of lithium ion battery

The negative electrode active material, artificial graphite, conductive agent Super-P, thickener CMC, and binder styrene-butadiene rubber (SBR) are dissolved in solvent deionized water at a weight ratio of 96:2:1:1 and mixed uniformly to make negative electrode slurry After that, the negative electrode slurry is evenly coated on the copper foil of the current collector, and then it is dried at 85°C and then cold pressed, trimmed, cut, and slit, and then dried under vacuum at 110°C for 4h, and the tabs are welded , Make the negative pole piece.

(3) Preparation of additive with coating layer

The aqueous phase containing the emulsifier is dispersed in the continuous phase of the polyethylene-xylene solution to form a water-in-oil (W/O) emulsion; then the W/O emulsion is re-dispersed in the additive aqueous solution to produce a W/O/W complex Phase emulsion: Once the W/O/W emulsion is produced, a certain amount of polyethylene-xylene solution solvent is added to make the polyethylene precipitate out of the xylene. After placing the microcapsules in an oven at 45°C for 1 hour, the additive with the coating layer can be obtained.

(4) Preparation of electrolyte for lithium ion batteries

In a glove box filled with argon gas, ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed at a weight ratio of EC:EMC=30:70 as a non-aqueous organic solvent. Lithium hexafluorophosphate is added to the non-aqueous organic solvent, the concentration of the lithium salt is 1.0 mol/L, and then 2% of the additive prepared in the above step (3) is added to the non-aqueous organic solvent, and the electrolyte is formed after uniform mixing.

(5) Isolation film

A 16μm polyethylene film (PE) is used as the separator.

(6) Preparation of lithium ion battery

Wrap the above-mentioned positive pole piece, separator film, and negative pole piece in order so that the separator is in the middle of the positive and negative pole pieces to obtain a bare cell, weld the tabs, and place the bare cell in the outer package. The electrolyte prepared above is injected into the dried cell, then charged to 3.3V with a constant current of 0.02C, then charged to 3.6V with a constant current of 0.1C, shaping, and capacity testing to complete the battery preparation.

In Examples 1-16 and Comparative Examples 1-6, the added amount of each additive used is shown in Table 1, where the added amount of each additive in Table 1 is calculated based on the weight percentage of the total weight of the electrolyte. .

Table 1

Note: "-" means no substance is added

The following tests were performed on the batteries prepared in Examples 1-16 and Comparative Examples 1-6:

(1) Battery capacity test of lithium ion battery

At 25℃, discharge the lithium-ion battery to 2.8V with a constant current of 1C for the first time. After standing for 10 minutes, charge with a constant current of 1C to 4.2V, charge with a constant voltage of 4.2V to a current of 0.05C, and then stand still. Leave it for 30 minutes, and then discharge it to 2.8V with a constant current of 1C for the second time, and take the second discharge capacity as the capacity of the lithium-ion battery.

(2) Hot box test of lithium ion battery

Take 5 sets of samples from the batteries prepared in each of the above examples and comparative examples, and charge them to 4.2V at 25°C with a constant current of 1C, and a constant voltage of 4.2V to a current of 0.5C, so that they are in a 4.2V fully charged state, and then Place the battery in a high-temperature box, raise it to 120°C at 2℃/min for 4h, measure the voltage change of the battery in the high-temperature box and the surface temperature of the battery, and observe the state of the battery after the test.

The results of the hot box test are shown in Table 2. The criteria for passing the test are: no smoke, no fire, no explosion from the battery. Through the above-mentioned hot box test, the safety performance of the battery is characterized.

Table 2 shows the results after the hot box test of the batteries prepared according to the comparative example and the examples.

Table 2

It can be seen from Examples 1-16 that the use of the additive with the coating layer of the present application can effectively improve the safety performance of the battery.

It can be seen from Comparative Examples 1-6 that the battery cannot be fully charged when the uncoated aniline and pyrrole additives are used. This is because the aniline and pyrrole additives form a polymer bridge between the positive electrode and the negative electrode, and the internal battery is slightly short-circuited. the reason.

The above are only specific implementations of this application, but the protection scope of this application is not limited to this. Anyone familiar with the technical field can easily think of various equivalents within the technical scope disclosed in this application. Modifications or replacements, these modifications or replacements shall be covered within the scope of protection of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

In addition, in those cases where conventions similar to "at least one of A, B and C, etc." are used, such structures usually have the meaning of conventions that those skilled in the art would understand (for example, "have A, B and "System with at least one of C" shall include but not limited to systems with A alone, B alone, C alone, A and B, A and C, B and C, and/or A, B and C, etc. ). In those cases where conventions similar to "at least one of A, B or C, etc." are used, such structures have the meaning of conventions that will be understood by those skilled in the art (for example, "having at least one of A, B or C" "One system" shall include, but is not limited to, A alone, B alone, C alone, A and B, A and C, B and C, and/or A, B and C, etc.). Those skilled in the art will further understand that, in fact, whether in the specification, claims or drawings, any abstract words and/or phrases that present two or more alternative terms should be understood as considering including these terms One, the possibility of one or both of these terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

In addition, where features or aspects of the present disclosure are described in terms of the Markush group, those skilled in the art will recognize that the application is therefore also described in terms of any single member or a subset of members of the Markush group.

Claims (14)

A battery additive. The battery additive includes a core structure and a coating layer covering the core structure, wherein the core structure includes one or more of an aniline compound and a pyrrole compound. The melting point of the coating layer is 80°C-150°C. The battery additive according to claim 1, wherein the pyrrole compound is selected from one or more of the compounds represented by formula (I),

Wherein R1 to R5 are each independently selected from a hydrogen atom, an amino group, a sulfonic acid group, a halogen atom, a substituted or unsubstituted C ₁ -C ₂₀ alkyl group, a substituted or unsubstituted C ₂ -C ₂₀ alkenyl group, a substituted or unsubstituted Substituted C ₆ -C ₂₆ aryl, substituted or unsubstituted C ₁ -C ₂₀ alkylsulfonyl, substituted or unsubstituted C ₂ -C ₂₀ alkenyl sulfonyl, substituted or unsubstituted C ₆ -C ₂₆ The arylsulfonyl group; and wherein the substituent is selected from a halogen atom, an amino group or a C ₁ -C ₄ alkyl group. The battery additive according to claim 2, wherein the pyrrole compound is selected from the group consisting of pyrrole, 1-phenylpyrrole, 3-acetylpyrrole, 2,4-dimethyl-3-acetylpyrrole, 3- Aminopyrrole, 1-(3-bromopropyl)pyrrole, 1-(4-fluorophenyl)pyrrole, 1-(4-iodophenyl)pyrrole, 3-methylpyrrole, 3-ethylpyrrole, 3- N-propylpyrrole, 3-butylpyrrole, 3-octylpyrrole, 3-decylpyrrole, 3-dodecylpyrrole, 3,4-dimethylpyrrole, 3,4-dibutylpyrrole, 3 -Methoxypyrrole, 3-ethoxypyrrole, 3-butoxypyrrole, 3-hexoxypyrrole, 3-methyl-4-hexoxypyrrole, 3-methyl-4-hexoxypyrrole One or more of 1-(2-aminophenyl)pyrrole and tosylpyrrole; optionally, the pyrrole compound is selected from one or more of pyrrole and 3-methylpyrrole. The battery additive according to claim 1, wherein the aniline compound is selected from the group consisting of aniline, 2-naphthylamine, 2-hydroxyaniline, p-hydroxyaniline, p-nitroaniline, o-aminoaniline, 1,3-benzene Diamine, diphenylamine, 2,4-dichloroaniline, 3,4-dichloroaniline, 2,4-difluoroaniline, 3,5-dichloroaniline, 3,4-dimethoxyaniline, 3- Hydroxy-N,N-dimethylaniline, 4-bromo-N,N-dimethylaniline, 2-methoxy-5-methylaniline, 3-methoxy-5-methylaniline, p-chloro One or more of aniline, p-bromoaniline, meta-bromoaniline, o-bromoaniline, and o-toluidine; optionally, the aniline compound is selected from one or more of 2-naphthylamine and diphenylamine . The battery additive according to claim 1, wherein the coating layer comprises polyvinyl chloride, polyethylene, ethylene-vinyl acetate, ethylene acrylic acid copolymer, chlorinated polyethylene, polyolefin elastomer POE, natural rubber , Butadiene rubber, polyisoprene, ethylene propylene rubber, styrene butadiene rubber; optionally, the coating layer includes one or more of polyethylene, ethylene-vinyl acetate Kind. The battery additive according to claim 1, wherein the weight ratio of the core structure to the coating layer is 30:1-10:1, optionally 25:1-15:1. The battery additive according to claim 1, wherein the average thickness of the coating layer is 10 μm to 30 μm, optionally 10 μm to 20 μm. A secondary battery, comprising the battery additive according to any one of claims 1-7. The secondary battery according to claim 8, comprising an outer package and a battery cell and electrolyte contained in the outer package, the battery cell including a positive pole piece, a negative pole piece and a separator, wherein the outer package At least one of the electrolyte, the positive pole piece, the negative pole piece, and the separator includes the battery additive according to any one of claims 1-7. The secondary battery according to claim 9, wherein at least one of the outer package and the electrolyte includes the battery additive according to any one of claims 1-7. The secondary battery according to claim 9, wherein the added amount of the battery additive accounts for 1% to 5% of the total weight of the electrolyte, optionally 1.5% to 3.5%. A battery module comprising the secondary battery according to any one of claims 8-11. A battery pack comprising the battery module according to claim 12. A device comprising at least one of the secondary battery according to any one of claims 8-11, the battery module according to claim 12, or the battery pack according to claim 13.

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