Battery cell and battery

Abstract

The utility model provides a battery cell and a battery, and the battery cell comprises a negative plate which comprises a negative current collector and a negative active material layer; the negative electrode current collector comprises a first wall surface, the first wall surface comprises a negative electrode energy area and a negative electrode fast charging area, the first wall surface is sequentially provided with the negative electrode fast charging area, the negative electrode energy area and the negative electrode fast charging area along a first direction, and the first direction is the width direction of the negative electrode plate; the negative electrode active material layer comprises a negative electrode fast charge active material layer and a negative electrode energy active material layer, and the charge-discharge speed of the negative electrode fast charge active material layer is higher than that of the negative electrode energy active material layer; the negative electrode fast charging active material layer is coated on the negative electrode fast charging area, and the negative electrode energy active material layer is coated on the negative electrode energy area; and a bulge or a groove is formed in the negative electrode quick charging area to accommodate more electrolyte. According to the battery cell disclosed by the utility model, the lithium precipitation phenomenon can be prevented.

Description

Technical Field

[0001] This utility model relates to the field of new energy technology, and in particular to a battery cell and battery. Background Technology

[0002] In existing technologies, to improve the energy density of battery cells, engineers set a higher density for the active material layer on the current collector, thereby increasing the cell's energy density. However, increasing the density of the active material layer can lead to lithium plating at the cell edges. This occurs because lithium ions released from the active material layer at the electrode edges cannot be readily incorporated into the negative electrode, resulting in lithium ion deposition and a reduction in cell capacity. To avoid this, engineers thin the active material layer at the edges of the positive electrode, reducing the rate of lithium ion release and thus preventing lithium plating. However, this method not only makes it difficult to control the electrode edge thickness but also reduces energy density. Therefore, a new type of battery cell is needed that can maintain energy density while avoiding lithium plating at the cell edges. Utility Model Content

[0003] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a battery cell that can prevent lithium plating at the edge of the battery cell.

[0004] This utility model also proposes a battery.

[0005] A battery cell according to an embodiment of the present invention includes: a negative electrode sheet, the negative electrode sheet comprising a negative electrode current collector and a negative electrode active material layer; the negative electrode current collector includes a first wall surface, the first wall surface comprising a negative electrode energy region and a negative electrode fast charging region, and is sequentially configured as a negative electrode fast charging region, a negative electrode energy region, and a negative electrode fast charging region along a first direction, the first direction being the width direction of the negative electrode sheet; the negative electrode active material layer comprises a negative electrode fast charging active material layer and a negative electrode energy active material layer, the lithium-ion insertion rate of the negative electrode fast charging active material layer being greater than the lithium-ion insertion rate of the negative electrode energy active material layer; the negative electrode fast charging active material layer is coated on the negative electrode fast charging region. The negative electrode energy active material layer is coated in the negative electrode energy region; a protrusion is provided on the side of the negative electrode fast-charging active material layer facing away from the negative electrode current collector, the height of the protrusion in the thickness direction of the negative electrode sheet is H, and the thickness of the negative electrode fast-charging active material layer in the thickness direction of the negative electrode sheet is A, 5%A≤H≤20%A; and / or; a groove is provided on the side of the negative electrode fast-charging active material layer facing away from the negative electrode current collector, the height of the groove in the thickness direction of the negative electrode sheet is D, and the thickness of the negative electrode fast-charging active material layer in the thickness direction of the negative electrode sheet is A, 5%A≤D≤30%A.

[0006] The battery cell according to the embodiments of this utility model has at least the following beneficial effects: a negative electrode fast-charging active material layer is provided at the edge of the battery cell, and the negative electrode fast-charging active material layer has a faster charging speed. That is, the negative electrode fast-charging active material layer has a faster lithium-ion insertion speed, thereby preventing lithium ions from depositing at the edge of the battery cell. At the same time, grooves and protrusions are provided in the negative electrode fast-charging active material layer, thereby improving the ability of the edge position of the battery cell, i.e., the negative electrode fast-charging area, to accommodate electrolyte, resulting in higher electrolyte wettability, thereby preventing lithium ions from depositing at the edge of the battery cell.

[0007] According to some embodiments of the present invention, the width of the negative electrode active material layer in the first direction is B, and the width of the negative electrode fast charging active material layer in the first direction is W, where 5%B≤W≤15%B.

[0008] According to some embodiments of this utility model, the battery cell further includes a positive electrode sheet, which includes a positive current collector and a positive active material layer; the positive current collector includes a second wall surface, which includes a positive energy region and a positive fast charging region, the positive energy region and the negative energy region being positioned correspondingly, and the positive fast charging region and the negative fast charging region being positioned correspondingly; the positive active material layer includes a positive fast charging active material layer and a positive energy active material layer, the lithium ion extraction rate of the positive fast charging active material layer is greater than the lithium ion extraction rate of the positive energy active material layer; the positive fast charging active material layer is coated on the positive fast charging region, and the positive energy active material layer is coated on the positive energy region.

[0009] According to some embodiments of the present invention, the surface density of the positive energy active material layer disposed in the positive energy region is greater than the surface density of the positive fast charging active material layer disposed in the positive fast charging region.

[0010] According to some embodiments of this utility model, the surface density of the negative electrode energy active material layer disposed in the negative electrode energy region is greater than the surface density of the negative electrode fast charging active material layer disposed in the negative electrode fast charging region.

[0011] According to some embodiments of this utility model, the width of the negative electrode fast charging area in the first direction is not less than 5mm.

[0012] According to some embodiments of the present invention, the overlapping area of ​​the orthographic projection of the negative energy region on the second wall surface and the positive energy region is not less than 90% of the area of ​​the orthographic projection of the negative energy region on the second wall surface, and the overlapping area of ​​the orthographic projection of the negative fast charging region on the second wall surface and the positive fast charging region is not less than 90% of the area of ​​the orthographic projection of the negative fast charging region on the second wall surface.

[0013] According to some embodiments of this utility model, the energy density of the negative electrode energy active material layer is greater than the energy density of the negative electrode fast-charging active material layer.

[0014] According to some embodiments of the present invention, the energy density of the positive electrode active material layer is greater than the energy density of the positive electrode fast-charging active material layer.

[0015] According to some embodiments of this utility model, the adjacent edges of the negative electrode energy region and the negative electrode fast charging region are fitted together.

[0016] According to some embodiments of the present invention, the edge of the negative electrode energy active material layer is attached to the edge of the adjacent negative electrode fast charging active material layer.

[0017] The battery according to other embodiments of the present invention includes the cell described in any of the above embodiments.

[0018] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the negative electrode current collector of the battery cell of this utility model;

[0020] Figure 2 This is a schematic diagram of the negative electrode plate of the battery cell of this utility model;

[0021] Figure 3 This is a schematic diagram of the positive current collector of the battery cell of this utility model;

[0022] Figure 4 This is a schematic diagram of the positive electrode plate of the battery cell of this utility model;

[0023] Figure 5 A front view of the negative electrode plate of the battery cell of this utility model, showing protrusions and grooves.

[0024] Figure 6 A cross-sectional schematic diagram showing the protrusions and grooves on the negative electrode plate of the battery cell of this utility model.

[0025] Icon labels:

[0026] 1. Negative electrode current collector; 11. Negative electrode energy region; 12. Negative electrode fast charging region; 21. Negative electrode energy active material layer; 22. Negative electrode fast charging active material layer; 3. Positive electrode current collector; 31. Positive electrode energy region; 32. Positive electrode fast charging region; 41. Positive electrode energy active material layer; 42. Positive electrode fast charging active material layer; 5. Protrusion; 6. Groove. Detailed Implementation

[0027] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0028] In the description of this utility model, it should be understood that the orientation descriptions, such as up and down, are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0029] In the description of this utility model, "multiple" refers to two or more. The use of "first" and "second" is for distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features or their sequential relationship.

[0030] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0031] Reference Figure 1The battery cell in the first embodiment of this utility model includes a negative electrode sheet. The negative electrode sheet includes a negative current collector 1 and a negative active material layer. The negative current collector 1 includes a first wall surface, which includes a negative energy region 11 and a negative fast charging region 12, and is sequentially arranged along a first direction, which is the width direction of the negative electrode sheet. The negative active material layer includes a negative fast charging active material layer 22 and a negative energy active material layer 21. The charging and discharging speed of the negative fast charging active material layer 22 is greater than that of the negative energy active material layer 21. The negative fast charging active material layer 22 is coated on the negative fast charging region 12, and the negative energy active material layer 21 is coated on the negative energy region 11. That is, the negative energy active material layer 21 is disposed in the middle position of the negative current collector 1, and lithium plating is less likely to occur in the middle position of the negative current collector 1. Therefore, the negative energy active material layer 21 can have a higher energy density. Specifically, the negative electrode fast-charging active material layer 22 has strong fast-charging properties. The fast-charging and energy properties of the active material layer are adjusted by the size of the crystal particles in the active material layer. When there are more large crystal particles, the active material layer has stronger energy properties, that is, it has a larger energy density. When there are fewer large crystal particles, the active material layer has stronger fast-charging properties, that is, it can enable lithium ions to intercalate or deintercalate more quickly.

[0032] The negative electrode active material layer on the negative electrode sheet is formed by one or more of graphite, hard carbon, soft carbon, lithium titanate, monocrystalline silicon, and silicon oxide. Taking graphite as the negative electrode active material layer as an example, in the negative electrode fast charging active material layer 22 set in the negative electrode fast charging region 12 of the negative electrode current collector 1, the proportion of small-particle graphite is higher, which has excellent rate performance and can achieve high-efficiency lithium ion insertion and extraction, thereby avoiding the lithium plating problem at the edge of the negative electrode sheet. In the negative electrode energy active material layer 21 set in the negative electrode energy region 11 of the negative electrode current collector 1, the proportion of large-particle graphite is higher, which can intercalate more lithium ions to achieve higher energy density. The percentage of large-particle graphite in the total active material layer of the negative electrode energy active material layer 21 is R1, and the percentage of large-particle graphite in the total active material layer of the negative electrode fast charging active material layer 22 is R2, which satisfies 1≥R1>R2≥0.3. This achieves both high energy density and avoids lithium plating at the cell edge.

[0033] The negative electrode fast-charging active material layer 22 has a protrusion 5 on the side facing away from the negative electrode current collector 1. The height of the protrusion 5 in the thickness direction of the negative electrode sheet is H, and the thickness of the negative electrode fast-charging active material layer 22 in the thickness direction of the negative electrode sheet is A, where 5%A≤H≤20%A; and / or, the negative electrode fast-charging active material layer 22 has a groove 6 on the side facing away from the negative electrode current collector. The height of the groove 6 in the thickness direction of the negative electrode sheet is D, and the thickness of the negative electrode fast-charging active material layer 22 in the thickness direction of the negative electrode sheet is A, where 5%A≤D≤30%A. The protrusion 5 and groove 6 on the negative electrode fast-charging active material layer 22 allow for the absorption of more electrolyte, ensuring sufficient electrolyte during fast charging and discharging, thus preventing lithium plating. The protrusion 5 and groove 6 can be created using methods such as embossing or laser drilling.

[0034] Furthermore, the width of the negative electrode active material layer in the width direction of the negative electrode sheet is B, and the width of the negative electrode fast-charging active material layer 22 in the width direction of the negative electrode sheet is W, where 5%B≤W≤15%B. By limiting the width of the negative electrode fast-charging active material layer 22, excessively low energy density of the battery cell is avoided.

[0035] Reference Figure 2 The battery cell also includes a positive electrode sheet, which includes a positive current collector 3 and a positive active material layer; the positive current collector 3 includes a second wall surface, which includes a positive energy region 31 and a positive fast charging region 32, the positive energy region 31 and the negative energy region 11 are positioned correspondingly, and the positive fast charging region 32 and the negative fast charging region 12 are positioned correspondingly; the positive active material layer includes a positive fast charging active material layer 42 and a positive energy active material layer 41, the charging and discharging speed of the positive fast charging active material layer 42 is greater than the charging and discharging speed of the positive energy active material layer 41; the positive fast charging active material layer 42 is coated on the positive fast charging region 32, and the positive energy active material layer 41 is coated on the positive energy region 31. Specifically, the positive electrode energy region 31 corresponds to the negative electrode energy region, and both the positive electrode active material layer 41 and the negative electrode active material layer 21 have high energy densities. The positive electrode fast charging region 32 corresponds to the negative electrode fast charging region 12, and both the negative electrode fast charging active material layer 22 and the positive electrode fast charging active material layer 42 have fast charging and discharging speeds. During cell discharge, lithium ions on the positive electrode active material layer 41 in the positive electrode energy region 31 of the positive electrode sheet are deintercalated and correspondingly intercalated into the negative electrode active material layer 21 in the corresponding negative electrode energy region 11 of the negative electrode sheet. Similarly, lithium ions on the positive electrode fast charging active material layer 42 in the positive electrode fast charging region 32 of the positive electrode sheet are deintercalated and correspondingly intercalated into the negative electrode fast charging active material layer 22 in the corresponding negative electrode fast charging region 12 of the negative electrode sheet.

[0036] The positive electrode active material layer on the positive electrode sheet includes one or more of the following: lithium vanadate, lithium titanate, lithium manganese oxide, lithium nickel oxide, lithium cobalt oxide, lithium cobalt phosphate, lithium iron phosphate, lithium manganese phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium nickel cobalt manganese aluminum oxide. Taking lithium cobalt oxide as the positive electrode active material layer as an example, in the negative electrode fast-charging active material layer 22 set in the positive electrode fast-charging region 32 of the positive electrode current collector 3, the proportion of small-particle lithium cobalt oxide is higher, which has excellent rate performance and can achieve high-efficiency lithium ion insertion / extraction and insertion, thereby avoiding the lithium plating problem in the edge region of the negative electrode sheet. In the positive electrode energy active material layer 41 set in the positive electrode energy region 31 of the positive electrode current collector 3, the proportion of large-particle lithium cobalt oxide is higher, which can accommodate more lithium ions to achieve higher energy density. In the positive electrode active material layer 41, the percentage of large-particle lithium cobalt oxide in the total active material layer is N1, and in the positive electrode fast-charging active material layer 42, the percentage of large-particle lithium cobalt oxide in the total active material layer is N2, satisfying 1≥N1>N2≥0.4. This design aims to achieve both high energy density and avoid lithium plating at the cell edges. Particles with a diameter greater than 10µm are considered large particles, and particles with a diameter less than 7µm are considered small particles.

[0037] The areal density of the positive energy active material layer 41 disposed in the positive energy region 31 is greater than the areal density of the positive fast charging active material layer 42 disposed in the positive fast charging region 32. The positive fast charging active material layer 42 on the positive fast charging region 32 is thinned, thereby reducing the amount of positive fast charging active material layer 42 on the positive fast charging region 32, thereby further avoiding the occurrence of lithium plating at the edge of the cell.

[0038] According to some embodiments of this utility model, the areal density of the negative electrode active material layer 21 disposed in the negative electrode energy region 11 is greater than the areal density of the negative electrode fast charging active material layer 22 disposed in the negative electrode fast charging region 12. Reducing the energy density of the positive electrode fast charging active material layer 42 increases the charging and discharging speed of the positive electrode fast charging active material layer 42. Correspondingly, reducing the energy density of the negative electrode fast charging active material layer 22 ensures that the charging and discharging speed of the negative electrode fast charging active material layer 22 is compatible with the charging and discharging speed of the positive electrode fast charging active material layer 42.

[0039] The area overlapping between the orthographic projection of the negative electrode energy region 11 and the positive electrode energy region 31 on the second wall surface is not less than 90% of the area of ​​the orthographic projection of the negative electrode energy region 11 on the second wall surface. Similarly, the area overlapping between the orthographic projection of the negative electrode fast charging region 12 and the positive electrode fast charging region 32 on the second wall surface is not less than 90% of the area of ​​the orthographic projection of the negative electrode fast charging region 12 on the second wall surface. Furthermore, the width of the negative electrode fast charging region 12 in the first direction is not less than 5 mm. This overlap of the negative electrode fast charging region 12 and the positive electrode fast charging region 32 allows lithium ions extracted from the positive electrode fast charging active material layer 42 to pass more quickly through the electrolyte and the separator before directly embedding into the negative electrode fast charging active material layer 22 on the negative electrode fast charging region 12. This avoids excessive energy loss due to the long migration distance of lithium ions. The electrolyte is prepared by mixing ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), and propyl propionate (PP) in a volume ratio of 1:1:4:4, and then dissolving fully dried lithium salt LiPF6 in the mixed organic solvent at a ratio of 1 mol / L.

[0040] The energy density of the negative electrode active material layer 21 is greater than that of the negative electrode fast-charging active material layer 22. By adjusting the ratio of large and small particles in the negative electrode active material layer 21 and compacting it, the negative electrode active material layer 21 has a larger density, thereby increasing the energy density of the battery cell.

[0041] The edges of adjacent negative electrode energy region 11 and negative electrode fast charging region 12 are bonded together. Negative electrode active material layer 21 covers negative electrode energy region 11, and negative electrode fast charging active material layer 22 covers negative electrode fast charging region 12, such that the edge of negative electrode active material layer 21 is bonded to the edge of adjacent negative electrode fast charging active material layer 22. Positive electrode fast charging active material layer 42 and positive electrode active material layer 41 are tightly bonded to avoid gaps between them that could cause lithium plating. The tight bonding of negative electrode fast charging active material layer 22 and negative electrode active material layer 21, along with accurate alignment with positive electrode fast charging active material layer 42 and positive electrode active material layer 41, reduces energy loss in the battery cell.

[0042] The battery according to other embodiments of the present invention includes any of the cells described in the above embodiments.

[0043] The embodiments of the present utility model have been described in detail above with reference to the accompanying drawings. However, the present utility model is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present utility model.

Claims

1. An electric cell, characterized by, Comprise: a negative electrode sheet comprising a negative electrode current collector and a negative electrode active material layer; the negative electrode current collector comprises a first wall surface comprising a negative electrode energy zone and a negative electrode fast charging zone, and is sequentially provided with a negative electrode fast charging zone, a negative electrode energy zone and a negative electrode fast charging zone along a first direction, the first direction being the width direction of the negative electrode sheet; the negative electrode active material layer comprises a negative electrode fast charging active material layer and a negative electrode energy active material layer, the lithium ion embedding speed of the negative electrode fast charging active material layer being greater than that of the negative electrode energy active material layer; the negative electrode fast charging active material layer is coated on the negative electrode fast charging zone, and the negative electrode energy active material layer is coated on the negative electrode energy zone; one side of the negative electrode fast charging active material layer opposite to the negative electrode current collector is provided with a protrusion, the height of the protrusion in the thickness direction of the negative electrode sheet is H, the thickness of the negative electrode fast charging active material layer in the thickness direction of the negative electrode sheet is A, and 5%A≤H≤20%A; and / or one side of the negative electrode fast charging active material layer opposite to the negative electrode current collector is provided with a groove, the height of the groove in the thickness direction of the negative electrode sheet is D, the thickness of the negative electrode fast charging active material layer in the thickness direction of the negative electrode sheet is A, and 5%A≤D≤30%A.

2. The electric cell of claim 1, wherein, The width of the negative electrode active material layer in the first direction is B, and the width of the negative electrode fast charging active material layer in the first direction is W, 5%B≤W≤15%B.

3. The electric cell of claim 1, wherein, The battery cell further comprises a positive electrode sheet comprising a positive electrode current collector and a positive electrode active material layer; the positive electrode current collector comprises a second wall surface comprising a positive electrode energy zone and a positive electrode fast charging zone, the positions of the positive electrode energy zone and the negative electrode energy zone corresponding to each other, and the positions of the positive electrode fast charging zone and the negative electrode fast charging zone corresponding to each other; the positive electrode active material layer comprises a positive electrode fast charging active material layer and a positive electrode energy active material layer, the lithium ion release speed of the positive electrode fast charging active material layer being greater than that of the positive electrode energy active material layer; the positive electrode fast charging active material layer is coated on the positive electrode fast charging zone, and the positive electrode energy active material layer is coated on the positive electrode energy zone.

4. The electric cell of claim 3, wherein, The area density of the positive electrode energy active material layer arranged in the positive electrode energy zone is greater than that of the positive electrode fast charging active material layer arranged in the positive electrode fast charging zone.

5. The electric cell of claim 1, wherein, The area density of the negative electrode energy active material layer arranged in the negative electrode energy zone is greater than that of the negative electrode fast charging active material layer arranged in the negative electrode fast charging zone.

6. The electric cell of claim 1, wherein, The width of the negative electrode fast charging zone in the first direction is not less than 5mm.

7. The cell of claim 3, wherein, The overlapping area of the positive projection of the negative electrode energy zone on the second wall surface and the positive electrode energy zone is not less than 90% of the area of the positive projection of the negative electrode energy zone on the second wall surface, and the overlapping area of the positive projection of the negative electrode fast charging zone on the second wall surface and the positive electrode fast charging zone is not less than 90% of the area of the positive projection of the negative electrode fast charging zone on the second wall surface.

8. The electric cell of claim 1, wherein, The energy density of the negative electrode energy active material layer is greater than that of the negative electrode fast charging active material layer.

9. The electric cell of claim 3, wherein, The energy density of the positive electrode energy active material layer is greater than the energy density of the positive electrode fast-charging active material layer.

10. The electric cell of claim 1, wherein, The edges of the negative electrode energy active material layer and the negative electrode fast-charging active material layer adjacent thereto are in abutment.

11. The electric cell of claim 10, wherein, The edges of the negative electrode energy active material layer and the negative electrode fast-charging active material layer adjacent thereto are in abutment.

12. A battery characterized by An electric battery comprising the electric cell of any one of claims 1-11.

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