CN104485481A - Lithium ion battery cell and lithium ion battery with same - Google Patents

Abstract

The invention discloses a lithium ion battery cell and a lithium ion battery with the same. The cell comprises a negative plate bag, wherein the negative plate bag is formed by a diaphragm bag and a negative plate arranged in the diaphragm bag; one outer surface of the diaphragm bag is also provided with a diaphragm frame; a positive plate is limited in the diaphragm frame. The lithium ion battery cell and lithium ion battery with the same, provided by the invention, are beneficial for improving the capacity keeping performance of lithium ions and avoiding the battery short circuit.

Description

Lithium-ion battery core body and lithium-ion battery with the battery core body

technical field

The invention relates to the field of lithium ion manufacturing, in particular to a lithium ion electric core body and a lithium ion battery with the electric core body.

Background technique

Since the commercialization of lithium-ion batteries in the 1990s, lithium-ion batteries have become one of the main power sources for portable electronic products such as mobile communications and notebook computers due to their high specific energy, high voltage, and high energy density.

Lithium-ion batteries in the prior art have defects such as high short-circuit rate and easy spontaneous combustion, and their capacity tends to decrease too quickly during use, and the battery life is short.

Contents of the invention

One of the objectives of the embodiments of the present invention is to provide a lithium-ion electric core body and a lithium-ion battery with the electric core body. The application of this technical solution is beneficial to improve the capacity retention of lithium ions and avoid battery short circuit.

A lithium ion battery core body provided by an embodiment of the present invention includes: a negative electrode sheet bag, the negative electrode sheet bag is made of a diaphragm bag and a negative electrode sheet contained in the diaphragm bag,

A diaphragm frame is also provided on an outer surface of the diaphragm bag,

The positive electrode sheet is limited in the diaphragm frame.

Optionally, the membrane pores on the membrane frame are larger than the membrane pores on the membrane bag.

Optionally, the outer edge of the membrane frame is flush with the outer edge of the membrane bag.

Optionally, the membrane frame is located within the surface area of the outer surface of the membrane bag.

Optionally, the center of the diaphragm frame is empty.

Optionally, the membrane frame includes membrane strips along the four sides of the membrane bag.

Optionally, the diaphragm frame is provided with a notch at the width end of the diaphragm bag, and the tab of the positive electrode protrudes from the notch.

Optionally, the membrane frame is bonded to the outer surface of the membrane bag.

Optionally, the membrane frame is melt-bonded and connected to the outer surface of the membrane bag.

A lithium-ion battery provided by an embodiment of the present invention includes: an electrolyte, and any one of the above-mentioned electric cores, the electric core and the electrolyte are jointly sealed in an aluminum-plastic film casing, so The electrolyte solution penetrates into the battery core body.

It can be seen from the above that by applying the technical solution of this embodiment, compared with the conventional technical solution of putting the narrower positive electrode sheet into the diaphragm bag in the prior art, this embodiment breaks through the traditional thinking in the above-mentioned prior art, and puts the wider negative electrode sheet into the diaphragm bag, so that both sides of the polar material coating area on the negative electrode sheet are separated from the outside by two opposite diaphragm sheets of the diaphragm bag. In this way, during the preparation of lithium-ion batteries, even if the polar material of the negative electrode sheet is scattered, due to the limitation of the diaphragm bag, the negative electrode powder is limited in the diaphragm bag and is not easy to overflow the diaphragm bag and contact with the positive electrode sheet, so as to avoid easy scattering The contact between the negative electrode powder and the positive electrode will cause the battery to short-circuit and cause the battery to spontaneously ignite.

In addition, a diaphragm frame is provided outside the diaphragm bag of the negative electrode sheet, and the positive electrode sheet is placed in the diaphragm frame. Under the fixation of the diaphragm frame, the positive electrode sheet is not easy to shift, avoiding the process of winding or stacking. The displacement of the positive electrode leads to the problem that the positive and negative electrodes are not aligned with each other.

Description of drawings

The drawings described here are used to provide a further understanding of the present invention, constitute a part of the present application, and do not constitute an improper limitation of the present invention.

Fig. 1 is a schematic diagram of a surface structure of a negative electrode bag provided in Example 1 of the present invention;

Fig. 2 is another schematic view of the surface structure of the negative electrode sheet bag shown in Fig. 1 in Example 1 of the present invention;

Fig. 3 is a schematic structural view after installing the positive electrode sheet in the diaphragm frame shown in Fig. 1 provided by Embodiment 1 of the present invention;

Fig. 4 is another schematic diagram of the structure provided by Embodiment 1 of the present invention after the positive electrode sheet is installed in the diaphragm frame shown in Fig. 1;

FIG. 5 is another structural schematic view provided by Embodiment 1 of the present invention after the positive electrode sheet is installed in the diaphragm frame shown in FIG. 1 .

Reference signs:

100: Negative electrode bag; 101: Diaphragm bag; 102: Negative electrode;

103: diaphragm frame; 104: positive plate; 105: positive ear;

106: Negative pole ear. the

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, where the schematic embodiments and descriptions of the present invention are used to explain the present invention, but not to limit the present invention.

Referring to FIGS. 1-3 , the lithium-ion battery body provided in this embodiment mainly includes: a negative electrode sheet bag 100 , which is made of a diaphragm bag 101 and a negative electrode sheet 102 contained in the diaphragm bag 101 .

When preparing the negative electrode sheet bag 100, two diaphragm sheets can be taken respectively, and the negative electrode sheet 102 is placed at intervals between the two diaphragm sheets, so that the negative electrode ear 106 of the negative electrode sheet 102 is stretched out from the edge of the width end of the diaphragm bag 101, and hot pressed The packaging equipment heat-presses the edge of the diaphragm to heat-seal the two diaphragms together to form a negative electrode pouch 100 with a negative electrode 102 sandwiched between the two diaphragms.

In this embodiment, a diaphragm frame 103 is also laid on an outer surface of the diaphragm bag 101 of the negative electrode sheet bag 100, and the diaphragm frame 103 is composed of diaphragm strips, and the positive electrode sheet 104 of the battery body is installed in the diaphragm frame 103, and It is limited by the diaphragm frame 103 around.

When preparing the wound electric core body, the above-mentioned stacked negative electrode sheet bag 100 and positive electrode sheet 104 are wound to obtain the wound electric core body of the lithium-ion battery.

When preparing the laminated cell body, according to the above structure, the above-mentioned structure composed of the negative electrode sheet bag 100 and the positive electrode sheet 104 is sequentially stacked to obtain the laminated cell body of the lithium-ion battery.

It can be seen from the above that, compared with the conventional technical solution of putting the narrower positive electrode sheet 104 into the diaphragm bag in the prior art, this embodiment breaks through the traditional thinking in the above-mentioned prior art, and puts the wider negative electrode sheet 102 into the diaphragm bag 101, The two sides of the polar material coating area on the negative electrode sheet 102 are respectively separated from the outside by two opposite diaphragm sheets of the diaphragm bag 101 . Like this, in lithium-ion battery preparation process, even if the polar material of negative electrode sheet 102 is scattered, but, because the limitation of separator bag 101, negative electrode powder is limited in separator bag 101 and is not easy to overflow separator bag 101 and positive electrode sheet 104 Contact, to avoid the problem that the easily scattered negative electrode powder is in contact with the positive electrode, which will cause a short circuit of the battery and cause the battery to spontaneously ignite.

In addition, a diaphragm frame 103 is provided outside the diaphragm bag 101 of the negative electrode sheet 102, and the positive electrode sheet 104 is placed in the diaphragm frame 103. Under the fixing of the diaphragm frame 103, the positive electrode sheet 104 is not easy to shift, avoiding the The displacement of the positive electrode sheet 104 during the winding process or lamination process leads to the problem that the positive and negative electrode sheets 102 are not aligned with each other.

As a schematic illustration of this embodiment, the diaphragm frame 103 of this embodiment is composed of diaphragm strips along the periphery of the diaphragm bag 101, the middle position of the diaphragm frame 103 is empty, and the positive electrode sheet 104 is just located in the hollow frame at the center of the diaphragm frame 103, so The design of the diaphragm frame 103 will not affect the thickness and capacity of the cell body. On the contrary, due to the design of the diaphragm frame 103, the battery can absorb more electrolyte. When the electrolyte is low, the absorbed electrolyte can be absorbed and released to avoid Insufficient electrolyte causes the problem of low battery capacity.

As an illustration of this embodiment, the porosity of the diaphragm on the diaphragm frame 103 of this embodiment is preferably, but not limited to, greater than that of the diaphragm of the diaphragm bag 101 . The diaphragm frame 103 has better liquid retention than the diaphragm bag 101. When the electrolyte is low, it can better absorb and release the absorbed electrolyte, avoiding the problem of low battery capacity caused by insufficient electrolyte.

As a schematic illustration of this embodiment, the outer edge of the diaphragm frame 103 of this embodiment is flush with the outer edge of the diaphragm bag 101, and the size of the hollow frame in the middle is consistent with the length and width of the positive electrode sheet 104, so that the positive electrode sheet 104 is just positioned on the diaphragm frame. 103 in the hollow frame, it is convenient for the stacking and positioning of the positive electrode sheet 104, improving the accuracy of stacking, ensuring the positive alignment between the positive electrode sheet 104 and the negative electrode sheet 102, and facilitating the process operation.

As a schematic illustration of this embodiment, referring to FIG. 4 , the diaphragm frame 103 can be arranged as shown in FIG. 4 , without a gap-free structure matching the shape of the positive tab 105 as shown in FIG. 4 .

Referring to Fig. 3, it is also preferred but not limited to be provided with a notch on the diaphragm frame 103 of this embodiment, the notch is located at the width end of the diaphragm bag 101, when the positive electrode sheet 104 is inserted into the hollow frame of the diaphragm frame 103, the positive electrode sheet The positive electrode ear 105 of 104 protrudes from the gap of the diaphragm frame 103 to further facilitate the positioning of the positive electrode sheet 104 .

As a schematic illustration of this embodiment, when the negative electrode sheet bag 100 is prepared, the diaphragm strip of the diaphragm frame 103 can be laid on the surface of the diaphragm bag 101. 101 outer surface. The separator frame 103 may also be bonded to the outer surface of the separator bag 101 by pasting or the like after the negative electrode sheet bag 100 is manufactured. the

After obtaining the lithium ion battery core body (wound battery core body or laminated battery core body) with the above structure, the battery core body is packaged with aluminum-plastic film and filled with electrolyte solution to obtain a lithium ion battery. In this battery, the cell body and the electrolyte are sealed together in an aluminum-plastic film casing, and the electrolyte penetrates into the cell body and is fully absorbed by the diaphragm bag 101 and the diaphragm frame 103 .

Test data analysis:

Example 2:

Using the laminated electric core body with the structure shown in Figure 1-3 in this embodiment 1, a laminated lithium ion battery sample is made, wherein the diaphragm porosity of the diaphragm frame 103 is 44%, and the diaphragm porosity of the diaphragm bag 101 is 38%. %, the specification of the laminated lithium ion battery sample is: ASP7042126-N2A-3700mAh. Among them, AS means pure cobalt aqueous negative electrode, 7042126 means the thickness, width, and length of the polymer lithium-ion battery are 7mm, 42mm, and 126mm, N means the nominal rate is 5C, 2 means the battery is a high-capacity type, A means positive Extremely pure lithium cobalt oxide, 3700 represents the nominal capacity of the battery.

Example 3:

This embodiment is consistent with the specification of the lithium ion battery sample in embodiment 2, and its difference is only in:

In this embodiment, the narrow positive electrode sheet is packaged in a diaphragm bag (i.e., the positive electrode sheet is put into a bag process), and the negative electrode sheet is stacked outside the diaphragm bag of the positive electrode sheet, and no diaphragm frame is arranged outside the diaphragm bag.

Because in the lithium-ion battery field, the width of the negative electrode sheet needs to be slightly larger than the width of the positive electrode sheet, it is also impossible to design a diaphragm frame for limiting the negative electrode sheet outside the diaphragm bag of the positive electrode sheet.

Example 4:

This embodiment is consistent with the specification of the lithium ion battery sample in embodiment 2, and its difference is only in:

There is no diaphragm frame outside the diaphragm bag, and the negative electrode sheet is directly stacked outside the diaphragm bag of the positive electrode sheet.

Example 5:

This embodiment is consistent with the specification of the lithium ion battery sample in embodiment 2, and its difference is only in:

A diaphragm frame is arranged outside the diaphragm bag, and the diaphragm porosity of the diaphragm frame is consistent with that of the diaphragm bag, both being 43%.

Embodiment 6:

This embodiment is consistent with the specification of the lithium ion battery sample in embodiment 2, and its difference is only in:

A diaphragm frame is arranged outside the diaphragm bag, and the diaphragm porosity of the diaphragm frame is smaller than that of the diaphragm bag.

Take 100 laminated lithium-ion battery samples obtained in Examples 2-6 respectively, and analyze the short circuit rate and low capacity rate according to the following test methods:

Short-circuit test: After the lamination is completed to obtain the laminated cell body, take 100 samples of the laminated cell body in each embodiment, and use an insulation internal resistance meter to perform a short-circuit test on the laminated cell body. A high-voltage voltage of 250V is given between the tabs of the negative pole to test the internal resistance of each cell. When the internal resistance of a certain cell reaches or exceeds 250MΩ, it is judged that the cell is qualified. A short circuit occurs, on the contrary, if the internal resistance of the cell body is less than 250MΩ, it is determined that the cell body is unqualified and a short circuit has occurred.

The inventor found during the experiment that if there is a diaphragm breakage or a burr in a cell, when a high voltage is applied to the cell, the diaphragm will break down, resulting in contact between the positive and negative electrodes of the cell. When the battery core is short-circuited, the circuit rate of the battery core can be effectively tested by the above test method.

Using the above method, the short-circuit rate of the cell samples of each embodiment can be obtained, as shown in Table 1 for details.

Capacity test: after aluminum-plastic film encapsulation, liquid injection, chemical formation, air extraction, and aluminum-plastic film secondary air-extraction encapsulation of the laminated battery core, each lithium-ion battery sample to be tested is placed in the Xinwei test cabinet. Carry out the capacity separation test, take 100 battery samples of each embodiment to carry out the above test, and none of the battery samples is short-circuited.

The battery sample is fully charged to 4.2V with a current of 0.5C, and then discharged to a cut-off voltage of 3.0V at 0.5C. If the discharge capacity is less than the standard capacity, it is judged as low capacity.

Taking the battery specification 7042126-N2A-3700mAh specified in this embodiment as an example, if the discharge capacity is less than 3700mAh, it is a low-capacity battery, and thus the test data shown in Table 1 is obtained.

Table 1: Experimental test data table

project short circuit rate low volume rate Example 2 0.05% 0.02% Example 3 0.13% 0.33% Example 4 0.06% 0.31% Example 5 0.05% 0.21% Example 6 0.06% 0.30%

It can be seen from the above that the battery samples and battery samples obtained in Examples 2, 4, 5, and 6 are much lower than the samples obtained in Example 3 in terms of short-circuit rate and low capacity rate of the battery. It should be noted that although the difference between Example 3 and Example 4 is only whether the positive electrode sheet or the negative electrode sheet is put into the separator bag, according to common sense, the performance of the battery core and the battery obtained should be similar, but Table 1 It can be seen from the data that the short-circuit rate and low capacity rate of the lithium-ion battery obtained by using the negative electrode sheet into the bag process are greatly reduced.

In addition, Examples 2, 4, 5, and 6 all use the negative electrode sheet into the bag, but the negative electrode sheet of Example 2, 5, and 6 is also provided with a diaphragm frame, which is a technical solution for setting a diaphragm frame relative to Example 4, and its The low capacity rate is greatly reduced.

In addition, Examples 2, 5, and 6 are all equipped with a diaphragm frame, but due to the relatively large diaphragm porosity of the diaphragm frame in Example 2, the corresponding low capacity of the battery is greatly reduced.

The implementation methods described above do not constitute a limitation to the scope of protection of the technical solution. Any modifications, equivalent replacements and improvements made within the spirit and principles of the above implementation methods shall be included in the protection scope of the technical solution.

Claims (10)

1. A lithium-ion electric core body, characterized in that it comprises: a negative electrode sheet bag, the negative electrode sheet bag is made of a diaphragm bag and a negative electrode sheet contained in the diaphragm bag, A diaphragm frame is also provided on an outer surface of the diaphragm bag, The positive electrode sheet is limited in the diaphragm frame. 2. The lithium ion battery core body according to claim 1, characterized in that, The membrane pores on the membrane frame are larger than the membrane pores on the membrane bag. 3. The lithium ion battery according to claim 1, characterized in that, The outer edge of the membrane frame is flush with the outer edge of the membrane bag. 4. The lithium ion battery core body according to claim 1, characterized in that, The membrane frame is located within the surface area of the outer surface of the membrane bag. 5. The lithium ion battery core body according to claim 1, characterized in that, The center position of the diaphragm frame is empty. 6. The lithium ion battery core body according to claim 5, characterized in that, The membrane frame includes membrane strips along the four sides of the membrane bag. 7. The lithium ion battery core body according to claim 6, characterized in that, The diaphragm frame is provided with a notch at the width end of the diaphragm bag, and the tab of the positive electrode protrudes from the notch. 8. The lithium ion battery core body according to claim 1, characterized in that, The diaphragm frame is bonded to the outer surface of the diaphragm bag. 9. The lithium ion battery core body according to claim 1, characterized in that, The membrane frame is melt-bonded and connected to the outer surface of the membrane bag. 10. A lithium-ion battery, characterized in that it comprises: electrolyte, any one of claims 1 to 9, the core body, the core body and the electrolyte are jointly sealed in an aluminum-plastic film casing , the electrolyte penetrates into the battery core body.