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US-12620581-B2 - Electrode piece and battery

US12620581B2US 12620581 B2US12620581 B2US 12620581B2US-12620581-B2

Abstract

The present disclosure provides an electrode piece and a battery. The electrode piece includes a current collector and a functional layer located on a first surface of the current collector, the first surface is provided with a tab, and the functional layer is composed of a normal area away from the tab and a recessed area near the tab, and a thickness of the recessed area is less than a thickness of the normal area. The present disclosure can effectively prevent problems such as excessive thickness of part of a cell near the tab, thereby improving battery qualities such as safety and charging/discharging rate.

Inventors

  • Shuanghu Zhang
  • Jian Zhang
  • Leiming SUN

Assignees

  • ZHUHAI COSMX BATTERY CO., LTD.

Dates

Publication Date
20260505
Application Date
20221201
Priority Date
20201230

Claims (20)

  1. 1 . An negative electrode piece, comprising a current collector and a functional layer located on a first surface of the current collector, wherein the first surface is provided with a tab, and the functional layer on the first surface is composed of a normal area away from the tab and a recessed area near the tab; the functional layer comprises an active material layer, and a thickness of the active material layer of the recessed area is less than a thickness of the active material layer of the normal area; and an active material of the active material layer comprises at least one selected from the group consisting of graphite, mesocarbon microbead, soft carbon, hard carbon, silicon material, silicon oxide material, silicon carbon material and lithium titanate material; an adhesive tape is provided on the surface of the tab facing away from the current collector, and the adhesive tape is adhered to at least a part of the recessed area; a gap is provided between the adhesive tape and the normal area along the length direction of the electrode piece; and a second surface of the current collector is opposite to the first surface, and the second surface is provided with an uncoated area; the uncoated area corresponds to the position of the tab of said first surface.
  2. 2 . The negative electrode piece according to claim 1 , wherein a width of the recessed area is 3-50 mm.
  3. 3 . The negative electrode piece according to claim 1 , wherein the thickness of the recessed area is 5-125 μm less than the thickness of the normal area.
  4. 4 . The negative electrode piece according to claim 3 , wherein a width of the recessed area is 3-50 mm.
  5. 5 . The negative electrode piece according to claim 1 , wherein the functional layer further comprises a bottom coating layer located between a surface of the current collector and the active material layer, wherein the bottom coating layer comprises an active material, a binder and a conductive agent, the active material layer comprises the active material, a binder and a conductive agent, and a content of the binder in the bottom coating layer is higher than a content of the binder in the active material layer.
  6. 6 . The negative electrode piece according to claim 5 , wherein a thickness of the bottom coating layer in the recessed area is 0-15 μm, and a thickness of an active material layer in the recessed area is 0-105 μm; and/or, a thickness of the bottom coating layer in the normal area is 5-15 μm, and a thickness of an active material layer in the normal area is 90-110 μm.
  7. 7 . The negative electrode piece according to claim 5 , wherein the active material layer is a porous structure with a porosity of 25%-50%.
  8. 8 . The negative electrode piece according to claim 5 , wherein the bottom coating layer is a porous structure with a porosity of 20%-45%.
  9. 9 . The negative electrode piece according to claim 5 , wherein the active material layer comprises the active material with a mass content of 93-96%, the binder with a mass content of 0.9-1.5%, and the conductive agent with a mass content of 1-3%.
  10. 10 . The negative electrode piece according to claim 5 , wherein the bottom coating layer comprises the active material with a mass content of 49-94%, the binder with a mass content of 4-50%, and the conductive agent with a mass content of 1-5%.
  11. 11 . A battery, comprising the negative electrode piece according to claim 1 .
  12. 12 . The battery according to claim 11 , wherein a width of the recessed area is 3-50 mm.
  13. 13 . The battery according to claim 11 , wherein the thickness of the recessed area is 5-125 μm less than the thickness of the normal area.
  14. 14 . The battery according to claim 13 , wherein a width of the recessed area is 3-50 mm.
  15. 15 . The battery according to claim 11 , wherein the functional layer comprises a bottom coating layer and an active material layer, the bottom coating layer is located between a surface of the current collector and the active material layer, materials for the bottom coating layer comprises an active material, a binder and a conductive agent; materials for the active material layer comprises an active material, a binder and a conductive agent, and a content of the binder in the bottom coating layer is higher than a content of the binder in the active material layer.
  16. 16 . The battery according to claim 15 , wherein a thickness of the bottom coating layer in the recessed area is 0-15 μm, and a thickness of an active material layer in the recessed area is 0-105 μm; and/or, a thickness of the bottom coating layer in the normal area is 5-15 μm, and a thickness of an active material layer in the normal area is 90-110 μm.
  17. 17 . The battery according to claim 15 , wherein the active material layer is a porous structure with a porosity of 25%-50%.
  18. 18 . The battery according to claim 15 , wherein the bottom coating layer is a porous structure with a porosity of 20%-45%.
  19. 19 . The battery according to claim 15 , wherein the materials for the active material layer comprise the active material with a mass content of 93-96%, the binder with a mass content of 0.9-1.5%, and the conductive agent with a mass content of 1-3%.
  20. 20 . The battery according to claim 15 , wherein the bottom coating layer comprises the active material with a mass content of 49-94%, the binder with a mass content of 4-50%, and the conductive agent with a mass content of 1-5%.

Description

CROSS-REFERENCE TO RELATED APPLICATION The present application is a continuation of International Application No. PCT/CN2021/139024, filed on Dec. 17, 2021, which claims priority to Chinese Patent Application No. 202011628643.2, filed with China National Intellectual Property Administration on Dec. 30, 2020, entitled “Electrode Piece and Battery”, both of which are hereby incorporated by reference in their entireties. TECHNICAL FIELD The present disclosure relates to the field of batteries, and in particular, to an electrode piece and a battery adopting the same. BACKGROUND Lithium-ion battery is widely used in consumer electronic products and electric vehicles due to its advantages of environment-friendly, high working voltage, high specific capacity and long cycle life, to improve qualities of the lithium-ion battery, such as fast charging capability as well as life and safety of the lithium-ion battery, and thus it is of great significance for the practical promotion and application of the battery. Coiled battery is a type of commonly used battery and is mainly prepared by laminating a positive electrode piece, a separator and a negative electrode piece and coiling to form a cell, and then subjecting to liquid injection, packaging, formation and other processes. However, a conventional cell is usually too thick at a position near a tab of an electrode piece. Especially when adopting an electrode piece in which the tab is designed in middle (rather than an end) of the electrode piece, due to the requirement for attaching an adhesive tape to the tab and other reasons, part of the cell near the tab is more likely to be too thick, exceeding the standard of thickness, resulting in the precipitation of lithium, the increase of battery internal resistance and other problems, which is not conducive to the safety of the battery, volume energy density of cell, and charging and discharging rate and other performance. SUMMARY The present disclosure provides an electrode piece to at least solve the problems existing in the prior art, such as excessive thickness of the cell near the tab and resulting low safety, poor charging and discharging rate performance of the battery and the like. The present disclosure further provides a battery that adopts the above electrode piece, to effectively avoid the problem of excessive thickness of the cell near the tab, and has a good charging and discharging rate performance, safety and long service life. In one aspect, the present disclosure provides an electrode piece, including a current collector and a functional layer located on a first surface of the current collector, where the first surface is provided with a tab, the functional layer on the first surface is composed of a normal area away from the tab and a recessed area near the tab, and a thickness of the recessed area is less than a thickness of the normal area. According to an embodiment of the present disclosure, the functional layer includes a bottom coating layer and an active material layer, the bottom coating layer is located between a surface of the current collector and the active material layer, raw materials of the bottom coating layer include an active material, a binder and a conductive agent, raw materials of the active material layer include an active material, a binder and a conductive agent, and a content of the binder in the bottom coating layer is higher than a content of the binder in the active material layer. According to an embodiment of the present disclosure, a thickness of the recessed area is 5-125 μm less than a thickness of the normal area. According to an embodiment of the present disclosure, a thickness of the bottom coating layer in the recessed area is 0-15 μm, a thickness of the active material layer in the recessed area is 0-105 μm; and/or, a thickness of the bottom coating layer in the normal area is 5-15 μm, and a thickness of the active material layer in the normal area is 90-110 μm. According to an embodiment of the present disclosure, a width of the recessed area is 3-50 mm. According to an embodiment of the present disclosure, the bottom coating layer is a porous structure with porosity of 20%-45%; and/or, the active material layer is a porous structure with a porosity of 25%-50%. According to an embodiment of the present disclosure, among the raw materials of the bottom coating layer, a mass content of the active material is 49-94%, a mass content of the binder is 4-50%, a mass content of the binder is 1-5%; and/or, among the raw materials of the active material layer, a mass content of the active material is 93-96%, a mass content of the binder is 0.9-1.5%, and a mass content of the conductive agent is 1-3%. According to an embodiment of the present disclosure, the electrode piece is a positive electrode piece, and the active material includes at least one of lithium cobaltate, lithium manganate, lithium nickelate, lithium nickel cobalt manganate, lithium ferrous phosphate, lithiu