CN213636086U

CN213636086U - Lithium ion battery cell

Info

Publication number: CN213636086U
Application number: CN202022054600.XU
Authority: CN
Inventors: 陈道明; 王桃环; 刘宏强; 丁浩; 周巨奎; 李雪红
Original assignee: Hefei Guoxuan High Tech Power Energy Co Ltd
Current assignee: Hefei Gotion High Tech Power Energy Co Ltd
Priority date: 2020-09-18
Filing date: 2020-09-18
Publication date: 2021-07-06
Anticipated expiration: 2030-09-18

Abstract

The utility model provides a lithium ion battery cell, including rolling up the core, roll up the core and convolute together by positive plate, negative pole piece, the barrier film of interval between positive plate and negative pole piece and form, roll up the core middle part and insert and be equipped with the gasket, the gasket includes first half gasket, the half gasket of second that the dislocation run from opposite directions set up, and first half gasket is symmetrical structure with half gasket of second. The utility model discloses introduce the gasket in the hot pressing process, through the curvature radius of increase book core both sides corner, prevent that negative pole piece corner from falling powder, leaking copper because of curvature radius undersize, tension are too big, prevent that the negative pole piece corner outside from taking place to analyse lithium at the circulation in-process, the utility model discloses a thickness, intensity and the hardness through the gasket increase the curvature radius of several rings of corners before the negative pole piece, improve the phenomenon that powder or even leaked copper because of the decarbonization of excessively bending and extrusion formation of its corner.

Description

Lithium ion battery cell

Technical Field

The utility model relates to a lithium cell technical field especially relates to a lithium ion battery electricity core.

Background

With the rapid development of new energy electric vehicles, particularly the application of lithium ion batteries and hybrid batteries in electric bicycles, electric vehicles and the like, the power batteries are required to have higher energy density and power density due to the complexity of the service conditions of the power batteries, and the safety, cycle performance and the like of the power batteries become more and more development bottlenecks of the new energy electric vehicles.

In the manufacturing process of the power battery, the curvature radius of the arc angle of the negative plate of the winding battery is larger because of the front circles of the inner layer, and the tension of the winding core diaphragm and the pole piece is larger, so that the arc angle of the negative plate of the front circles of the inner layer of the winding core is subjected to powder removal, and the phenomenon that negative powder falls off in a strip shape or even leaks a current collector copper foil is caused. In the power battery trial-manufacture hot pressing in-process, can apply a pressure with the battery plastic, at this in-process, can increase the atress of rolling up core arc angle, after soaking with electrolyte, can make the adhesion force between powder and the mass flow body descend, several rings of arc angles before rolling up core inner layer negative plate fall the possibility of powder, it can lead to the lithium risk of analysing of battery in the circulation process to fall the powder to roll up core inner layer negative plate corner, in the battery full life cycle, can have very big risk, thereby cause the incident. Patent No. CN202503079U discloses a lithium ion battery electricity core, utilize the mode of coiling, at the inside gasket of coiling of core, effectively increased the curvature radius of negative pole piece when coiling, improved the phenomenon that its corner falls whitewashed or even leaks copper because of the decarbonization of excessive bending and extrusion formation, but the mode of coiling increase gasket can increase the width of rolling up the core and the weight of battery, influence the energy density of battery, bring certain limitation in the aspect of giving the battery design.

SUMMERY OF THE UTILITY MODEL

Based on the technical problem who exists among the background art, the utility model provides a lithium ion battery electricity core.

The utility model provides a lithium ion battery cell, including rolling up the core, roll up the core and convolute together by positive plate, negative pole piece, the barrier film of interval between positive plate and negative pole piece and the gasket that is located the middle part and form, the gasket includes the first half gasket, the half gasket of second that the dislocation run from opposite directions set up, and first half gasket is symmetrical structure with half gasket of second.

Preferably, the gasket further comprises an elastic member, and the elastic member is connected with the ends of the first half gasket and the second half gasket.

Preferably, the outer surfaces of the first half gasket and the second half gasket are flat cambered surfaces.

Preferably, the thickness of the first half gasket and the second half gasket is 1.0-3.0 mm.

Preferably, the first half gasket and the second half gasket are made of PE or PP.

Preferably, the first half gasket and the second half gasket are only in contact with the isolation film.

The utility model provides a lithium ion battery cell, the core is rolled up by positive plate, negative pole piece, the barrier film of interval between positive plate and negative pole piece and is formed together, is inserted in the middle part of the core and is equipped with the gasket, introduces the gasket in hot pressing process, through increasing the radius of curvature of the corner of roll core both sides, prevents that the negative pole piece corner from falling powder, leaking copper because of radius of curvature undersize, tension oversize, prevent that the outside of negative pole piece corner from taking place to analyse lithium in the circulation process, the utility model discloses a through the thickness of gasket, intensity and hardness increase the radius of curvature of several rings of corners before the negative pole piece, improve the decarbonization of its corner because of excessive bending and extrusion and fall the phenomenon of powder or even leaking copper; when hot pressing, different gaskets can be designed according to the length and the width of different winding cores. The utility model discloses a powder that improves the roughness of rolling up the core and negative pole piece corner through the gasket at the hot pressing process drops, leaks the copper phenomenon, to a certain extent, can improve the battery because of the deformation problem of the inside book core that the long circulation arouses to improve lithium ion battery's cyclicity ability and security performance.

Drawings

Fig. 1 is a schematic structural diagram of a lithium ion battery cell provided by the present invention;

fig. 2 is a schematic structural diagram of a gasket in a lithium ion battery cell according to the present invention;

fig. 3 is a schematic diagram of the results of the capacity retention rate of the cycle test according to the embodiment and the comparative example of the present invention.

Detailed Description

Example 1

Referring to fig. 1 and 2, the utility model provides a lithium ion battery electric core, including rolling up the core, it is formed by positive plate 1, negative plate 2, the barrier film 3 of interval between positive plate 1 and negative plate 2 convoluteing together to roll up the core middle part, it is equipped with gasket 4 to roll up the core middle part insert, gasket 4 including the dislocation run from opposite directions first half gasket 41, the half gasket 42 of second and with first half gasket 41, the half gasket 42 end connection's of second elastic component 43, first half gasket 41 is symmetrical structure with half gasket 42 of second, and first half gasket 41 forms the gasket that is similar to shuttle structure with half gasket 42 combination together with half gasket 42 of second, and the surface of first half gasket 41, half gasket 42 of second is flat cambered surface.

The utility model discloses during hot pressing, first half gasket 41 and second half gasket 42 are combined together and are inserted in the roll core, then rely on elastic component 43 to strut in the roll core, will roll up the smooth hot pressing platform of putting into of core, carry out hot pressing, because of the supporting role of gasket, the first several circles arc angular position of negative pole piece can not take place to fall the powder and appear leaking the copper phenomenon because of excessive bending and hot pressing, especially in the battery long cycle process effectual prevention negative pole piece first several circles arc angular position lithium analysis condition; and taking out the gasket 4 after the hot pressing is finished.

The widths and the lengths of the first half gasket 41 and the second half gasket 42 can be designed into different sizes according to the length and the width of the winding core, and the half gasket is suitable for batteries with different models. The thickness of the gasket 4 is not easy to be too thin and too thick, the improvement effect of the curvature radius of the corners of the gasket is not obvious before the negative pole piece, when the gasket is too thick, the hot pressing of the thickness of the winding core cannot be realized, the laminating effect of the internal pole piece is not good, the electrical property of the battery is influenced, the safety of the battery can be further brought, meanwhile, the excessive thickness of the winding core can also bring the abnormity of the manufacturing process, and the winding core is difficult to enter the shell. In this embodiment, the thickness of the used spacer 4 is 2.0mm, the length of the spacer is 146mm, and the width of the spacer is 65 mm.

In an embodiment, the first half gasket 41 and the second half gasket 42 are made of PE or PP.

In the specific embodiment, the first half shim 41 and the second half shim 42 only contact with the release film 3 and do not adhere to the release film 3, so that the situation of core pulling when the shim is pulled out of the winding core is avoided.

The utility model discloses battery electricity core preparation step is as follows:

and manufacturing the negative electrode sheet 12:

adding graphite, a binder 1, a binder 2, conductive carbon black and carbon nanotubes into a solvent according to the mass percentage of 94.0:1.8:2.0:1.2:1.0, and uniformly stirring to prepare negative electrode slurry; the slurry was then coated onto a copper foil having a thickness of 9um and a coating weight of 47g/m²And the thickness of the rolled negative plate 2 is 76 +/-2 um. And after cutting, the width of the effective film is 120mm, a blank copper foil is left on one side of the effective film for 11mm, and no blank copper foil is left on the other side of the effective film for preparing the negative plate 2.

Manufacturing a positive plate 13:

adding nickel cobalt lithium manganate (LiNiCoMnO2), conductive carbon black, carbon nano tubes and a binder into a solvent according to the mass percentage of 95.3:1.4:1.8:1.5, and uniformly stirring to prepare anode slurry; the slurry was then coated on an aluminum foil having a thickness of 20um at a coating weight of 80g/m²And the thickness of the positive plate 1 after rolling is 68 +/-2 um. And after cutting, the effective film width is 117mm, a blank aluminum foil is left on one side for 13mm, and no blank aluminum foil is left on the other side, so that the positive plate 1 is prepared.

The diaphragm 11 is a polypropylene microporous ceramic diaphragm with the thickness of 12+4 um.

The preparation steps of the winding core 10 are as follows: firstly, the diaphragm 11 is rolled on a rolling needle for 1 circle and half, then the negative plate 2 is inserted into the middle of the isolating film 3, after the negative plate is wound for one circle, the positive plate 1 is inserted into the upper-layer diaphragm for winding, finally, the length of the negative plate 2 exceeds the length of the positive plate 1 by 5-8mm, then the isolating film 3 is wound for one circle again, the ending negative plate 2 is wrapped, the isolating film 3 is pasted with green glue to fix a roll core, and the roll core is manufactured.

In the hot pressing step, the gasket 4 is inserted into the core, and then the

half gaskets

41 and 42 are sprung apart by the intermediate elastic member 43 to support the core and flatten it, and the hot pressing operation is started.

Assembling, baking, injecting electrolyte, and performing formation, capacity grading and other processes to obtain the lithium ion battery cathode sheet improved method.

Example 2

Unlike embodiment 1, the spacer 4 has a thickness of 1.0mm, and the rest is the same as embodiment 1.

Comparative example

Unlike example 1, this example is hot-pressed without interposing a gasket during hot-pressing, and is otherwise the same as embodiment 1.

And (4) safety performance testing:

table 1: test results of 50-week high-current charge-discharge cycle (10C/20C, 3.0V-4.1V, 25 ℃ C.)

From the experimental results in table 1, it can be seen that, at 25 ℃, 10C/20C, and 3.0V-4.1V, cycle 50 cycles of disassembly results, strip-shaped powder falling, copper leakage and slight lithium separation occur at the front three corners of the head of the negative electrode in the comparative example, and negative electrode powder falling, copper leakage and lithium separation do not occur after the core of the winding after hot pressing by using the gasket is disassembled, so that it can be seen that, during hot pressing, the gasket 4 is inserted into the core of the winding, the core of the winding is flatly opened, and depending on a certain thickness of the gasket, the phenomena of powder falling and copper leakage occurring at the front several circles of arc angle positions of the negative electrode sheet due to excessive bending and hot pressing can be effectively improved, and especially, the lithium separation at the front several circles of arc angle positions of the negative electrode sheet can be effectively prevented in the long cycle process of.

Cycle life test

The batteries of example 1 and example 2 and the comparative example were subjected to a cycle test under the conditions of 25 ℃ and a cycle charge and discharge experiment at a rate of 5C/5C, and the charge and discharge modes were constant-current constant-voltage charge-rest-constant-current discharge, the charge cut-off voltage was 4.2V, the discharge cut-off voltage was 3.0V, and the rest sleep time was 10 min. The number of cycles was 1000, and the remaining capacity (capacity retention ratio) was calculated as follows:

capacity retention rate ═ (last one-week discharge capacity ÷ first-week discharge capacity) × 100%

As shown in fig. 3, the cycle test result shows that the capacity retention rate of the lithium ion battery cell of example 1 is the highest, and the capacity retention rate is 92% at 1500 weeks, and that the capacity retention rate of the lithium ion battery cell of example 2 is 91.3% at 1500 weeks, and the worst non-improved lithium ion battery cell belonging to the comparative example has a capacity retention rate of only 88.9%. This shows that when the core is rolled up in the hot pressing, insert a gasket 4 at first in rolling up the core inside, will roll up the smooth opening of core, rely on the certain thickness of self of gasket, can effectual improvement several rings of arc angle positions before the negative pole piece take place to fall the powder and appear leaking the copper phenomenon because excessive bending and hot pressing.

The above, only be the concrete implementation of the preferred embodiment of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art is in the technical scope of the present invention, according to the technical solution of the present invention and the utility model, the concept of which is equivalent to replace or change, should be covered within the protection scope of the present invention.

Claims

1. The utility model provides a lithium ion battery electric core, its characterized in that, includes rolls up the core, roll up the core and be formed by positive plate (1), negative pole piece (2), interval barrier film (3) between positive plate (1) and negative pole piece (2) convolute together, roll up the core middle part and insert and be equipped with gasket (4), gasket (4) are half first gasket (41), the half gasket (42) of second including dislocation run from opposite directions setting, and half first gasket (41) are symmetrical structure with half gasket (42) of second.

2. The lithium ion battery cell of claim 1, wherein the gasket further comprises an elastic member (43), and the elastic member (43) is connected with the ends of the first half gasket (41) and the second half gasket (42).

3. The lithium ion battery cell of claim 1, wherein the outer surfaces of the first half gasket (41) and the second half gasket (42) are flat cambered surfaces.

4. A lithium ion battery cell according to any of claims 1 to 3, characterised in that the thickness of the first half shim (41) and the second half shim (42) is 1.0 to 3.0 mm.

5. A lithium ion battery cell according to any of claims 1 to 3, characterized in that the first half gasket (41) and the second half gasket (42) are made of PE or PP.

6. A lithium-ion battery cell according to any of claims 1 to 3, characterized in that the first half gasket (41) and the second half gasket (42) are in contact with the separator film (3) only.