Positive electrode plate of lithium battery

Abstract

The utility model discloses a positive electrode plate of a lithium battery, which comprises a positive electrode plate body, a tab is welded on the positive electrode plate body, adhesive tapes are respectively adhered to two ends of the positive electrode plate body, and the middle parts of the adhesive tapes are bent into C shapes and are attached to the end parts of the positive electrode plate body. According to the utility model, the positive plate body is firstly cut, and after cutting is finished, the two ends of the positive plate body are wrapped by the adhesive tape, so that the phenomenon that the adhesive tape is cut, so that plaster is accumulated and rolled into a pole group to crush the pole plate can be avoided; the adhesive tape is arranged in the C shape, so that the end face of the positive plate body is effectively prevented from abrading or puncturing the diaphragm, meanwhile, relative displacement of the adhesive tape and the pole piece caused by expansion and contraction of the pole piece in the charge-discharge cycle process of a battery cell can be avoided, and the possibility that metal is exposed on the end face of the positive plate body is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of lithium ion batteries, and in particular relates to a positive electrode sheet of a lithium battery. Background Art

[0002] Existing lithium-ion batteries are generally manufactured by winding a positive electrode sheet, a negative electrode sheet, and a separator in a sequentially overlapping manner. Therefore, during the winding process of lithium-ion batteries, the positive electrode sheet needs to be cut. Due to the high compaction density of the positive electrode sheet, the cutting process will form metal burrs on the end surface of the positive electrode sheet. As the electrode sheet expands and contracts during the battery's charge and discharge, burrs on the end surface of the positive electrode sheet or exposed current collector may pierce the separator and short-circuit with the negative electrode on the other side of the separator, posing a safety risk.

[0003] By covering the current collector and burrs at the cut part of the positive electrode sheet with the upper and lower layers of tape, it is possible to prevent the current collector on the end face of the positive electrode sheet from wearing through the diaphragm or the burrs from piercing the diaphragm due to the expansion and contraction of the electrode sheet during the charge and discharge process of the battery cell.

[0004] However, in actual use, as the electrode expands and contracts during the battery charging and discharging process, the tape will be squeezed and will form a relative displacement with the electrode, resulting in the current collector on the end face of the positive electrode and the burrs on the current collector being exposed, and the diaphragm will still be worn through or pierced to form an internal short circuit in the battery. Utility Model Content

[0005] The purpose of this utility model is to provide a positive electrode sheet for a lithium battery to solve the problems raised in the above-mentioned background art. The positive electrode sheet provided by this utility model has the characteristic of preventing relative displacement between the tape and the electrode sheet caused by expansion and contraction of the electrode sheet during the charging and discharging of the battery cell.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a positive electrode sheet of a lithium battery, comprising a positive electrode sheet body, a pole ear welded on the positive electrode sheet body, and adhesive tapes respectively adhered to the two ends of the positive electrode sheet body, with the middle part of the adhesive tape bent into a "C" shape and attached to the end of the positive electrode sheet body.

[0007] In order to provide space for the cutting process, the positive electrode sheet body further includes a current collector, which is an aluminum foil component with a thickness of 10um-20um. A coating is provided on both sides of the current collector, and a cutting empty foil area is provided on the current collector.

[0008] In order to provide space for the welding of the tabs, a tab empty foil area is further provided on the current collector.

[0009] In order to prevent the end face of the positive electrode sheet from being squeezed during the bending process of the tape, thereby causing wrinkles in the positive electrode sheet, the bending point of the tape is further 1-2 mm away from the end face of the current collector.

[0010] In order to prevent the foil from leaking due to fluctuations in the device, the length of the tape covering the coating is 1-2 mm, and the width of the tape is greater than the width of the current collector.

[0011] In order to protect the exposed current collector and prevent the tab from falling off the current collector, a protective layer is further provided on the outside of the welding point between the tab and the positive electrode body.

[0012] Compared with the prior art, the beneficial effects of the present invention are:

[0013] 1. The utility model first performs a cutting process on the positive electrode body. After the cutting is completed, the two ends of the positive electrode body are wrapped with tape to prevent the cutting tape from causing the accumulation of adhesive mud, which may be drawn into the electrode group and cause damage to the electrode sheet;

[0014] 2. The adhesive tape of the present invention is arranged in a C-shape, which effectively prevents the end face of the positive electrode body from grinding through or piercing the diaphragm. At the same time, it can avoid the relative displacement between the adhesive tape and the electrode due to the expansion and contraction of the electrode during the charge and discharge cycle of the battery cell, thereby reducing the possibility of exposed metal on the end face of the positive electrode body;

[0015] 3. The bending part of the tape of the utility model is 1-2mm away from the end face of the current collector to prevent the tape from squeezing the end face of the positive electrode body during bending, which may cause wrinkles on the positive electrode body;

[0016] 4. The length of the tape covering the coating of the utility model is 1-2mm, and the width of the tape is greater than the width of the current collector to prevent the foil from leaking due to equipment fluctuations;

[0017] 5. A protective layer is provided on the outside of the welding point between the electrode tab and the positive electrode body of the utility model, which can protect the exposed current collector on the one hand and prevent the electrode tab from falling off the current collector on the other hand. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural diagram of the utility model;

[0019] Figure 2 This is a schematic diagram of the top structure of the utility model;

[0020] Figure 3 This is a schematic structural diagram of the positive electrode body of the utility model;

[0021] In the figure: 1. Positive electrode body; 2. Tape; 3. Protective layer; 4. Tab; 5. Current collector; 6. Coating; 7. Tab empty foil area; 8. Cut empty foil area. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0023] Example 1

[0024] See also Figure 1-3 The utility model provides the following technical solutions: a positive electrode sheet of a lithium battery, comprising a positive electrode sheet body 1, a tab 4 welded on the positive electrode sheet body 1, and adhesive tape 2 adhered to both ends of the positive electrode sheet body 1. The base material of the adhesive tape 2 is PI or PET, and the adhesive layer is a high-temperature protective tape such as acrylic adhesive or rubber. In this embodiment, the base material is preferably PET, and the adhesive layer is preferably acrylic adhesive. The middle part of the adhesive tape 2 is bent into a "C" shape and attached to the end of the positive electrode sheet body 1.

[0025] By adopting the above technical solution, the utility model first performs a cutting process on the positive electrode sheet body 1. After the cutting is completed, the two ends of the positive electrode sheet body 1 are wrapped with tape 2, which can avoid the accumulation of glue mud caused by cutting the tape 2, and the accumulation of glue mud caused by being drawn into the electrode group and causing damage to the electrode sheet; the tape 2 of the utility model is set in a C shape, which effectively prevents the end face of the positive electrode sheet body 1 from being worn through or piercing the diaphragm, and at the same time can avoid the relative displacement of the tape 2 and the electrode sheet due to the expansion and contraction of the electrode sheet during the charge and discharge cycle of the battery cell, thereby reducing the possibility of exposed metal on the end face of the positive electrode sheet body 1.

[0026] Specifically, the positive electrode body 1 includes a current collector 5, which is an aluminum foil component with a thickness of 10um-20um, preferably 15um in this embodiment. A coating 6 is provided on both sides of the current collector 5. The coating 6 is an active material coating for embedding and de-embedding lithium ions to realize the function of storing and passing electrical energy of the lithium battery, and a cut empty foil area 8 is provided on the current collector 5.

[0027] By adopting the above technical solution, space is provided for the cutting process.

[0028] Example 2

[0029] The difference between this embodiment and embodiment 1 is that: specifically, a tab hollow foil area 7 is further provided on the current collector 5 .

[0030] By adopting the above technical solution, space is provided for welding the tab 4 .

[0031] Example 3

[0032] The difference between this embodiment and embodiment 1 is that: specifically, the bending point of the tape 2 is 1-2 mm away from the end surface of the current collector 5.

[0033] By adopting the above technical solution, the adhesive tape 2 is prevented from squeezing the end surface of the positive electrode sheet body 1 during the bending process, thereby preventing the positive electrode sheet body 1 from wrinkling.

[0034] Specifically, the length of the adhesive tape 2 covering the coating 6 is 1-2 mm, and the width of the adhesive tape 2 is greater than the width of the current collector 5 .

[0035] By adopting the above technical solution, foil leakage caused by equipment fluctuations can be prevented.

[0036] Example 4

[0037] The difference between this embodiment and embodiment 1 is that: specifically, a protective layer 3 is provided on the outside of the welding point between the tab 4 and the positive electrode body 1, the protective layer 3 is made of a base material PI, and the adhesive layer is an acrylic adhesive tape.

[0038] By adopting the above technical solution, on the one hand, the exposed current collector 5 can be protected, and on the other hand, the tab 4 can be prevented from falling off the current collector 5 .

[0039] The forming method of the cut empty foil area 8 in the present invention includes but is not limited to: continuously coating the coating 6 on the current collector 5, and then scraping off the coating 6 at the corresponding position; coating the coating 6 at the non-cutting position on the current collector 5, and stopping coating the coating 6 at the cutting position to form the cut empty foil area 8, etc.

[0040] In summary, the present invention first performs a cutting process on the positive electrode sheet body 1. After the cutting is completed, the two ends of the positive electrode sheet body 1 are wrapped with the adhesive tape 2, which can avoid the accumulation of adhesive mud caused by cutting the adhesive tape 2, which is rolled into the electrode group and causes damage to the electrode sheet; the adhesive tape 2 of the present invention is set in a C shape, which effectively prevents the end face of the positive electrode sheet body 1 from being worn through or pierced through the diaphragm, and at the same time can avoid the relative displacement of the adhesive tape 2 and the electrode sheet due to the expansion and contraction of the electrode sheet during the charge and discharge cycle of the battery cell, thereby reducing the possibility of exposed metal on the end face of the positive electrode sheet body 1; the present invention The bending point of the new tape 2 is 1-2 mm away from the end face of the current collector 5 to prevent the tape 2 from squeezing the end face of the positive electrode body 1 during the bending process, causing wrinkles in the positive electrode body 1; the length of the coating 6 covered by the tape 2 of the utility model is 1-2 mm, and the width of the tape 2 is greater than the width of the current collector 5 to prevent foil leakage caused by equipment fluctuations; the outside of the welding point between the electrode ear 4 and the positive electrode body 1 of the utility model is provided with a protective layer 3, which can protect the exposed current collector 5 on the one hand and prevent the electrode ear 4 from falling off the current collector 5 on the other hand.

[0041] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A positive electrode sheet for a lithium battery, characterized in that: It includes a positive electrode body, on which a tab is welded, and adhesive tapes are respectively adhered to both ends of the positive electrode body, wherein the middle portion of the adhesive tape is bent into a "C" shape and attached to the end of the positive electrode body.

2. The positive electrode sheet of a lithium battery according to claim 1, characterized in that: The positive electrode sheet body comprises a current collector, both sides of the current collector are provided with coatings, and a cut-out empty foil area is provided on the current collector.

3. The positive electrode sheet of a lithium battery according to claim 2, characterized in that: The current collector is an aluminum foil component with a thickness of 10um-20um.

4. The positive electrode sheet of a lithium battery according to claim 2, characterized in that: The current collector is also provided with a tab empty foil area.

5. The positive electrode sheet of a lithium battery according to claim 2, characterized in that: The bending point of the tape is 1-2 mm away from the end surface of the current collector.

6. The positive electrode sheet of a lithium battery according to claim 2, characterized in that: The length of the tape covering coating is 1-2 mm.

7. The positive electrode sheet of a lithium battery according to claim 2, characterized in that: The width of the tape is greater than the width of the current collector.

8. The positive electrode sheet of a lithium battery according to claim 1, characterized in that: A protective layer is provided on the outside of the welding point between the electrode tab and the positive electrode body.

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