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CN-122026025-A - Secondary battery, method for manufacturing secondary battery, and electronic device

CN122026025ACN 122026025 ACN122026025 ACN 122026025ACN-122026025-A

Abstract

The application provides a secondary battery, a preparation method of the secondary battery and electronic equipment. The secondary battery comprises a shell and an electrode assembly arranged in the shell, wherein the electrode assembly comprises a first pole piece, a second pole piece and a diaphragm, the diaphragm is arranged between the adjacent first pole piece and second pole piece, the first pole piece comprises a first current collector and a first active material layer, the first current collector is provided with a first end face along a first direction, the first direction is perpendicular to the thickness direction of the first current collector, a plurality of bulges are arranged on the first end face, at least part of surfaces of at least one bulge are arc-shaped, a first layer of film is arranged on the surface of the first end face, metal oxide is included in the first layer of film, the metal oxide in the first layer of film is selected from at least one of aluminum oxide and copper oxide, and the bulges are covered by the first layer of film. The possibility of the edge burr of the first current collector piercing or tearing the separator, generating free metal chips, and causing a short circuit is reduced.

Inventors

  • CHI JINFENG

Assignees

  • 宁德新能源科技有限公司

Dates

Publication Date
20260512
Application Date
20260410

Claims (17)

  1. 1. A secondary battery, characterized in that, The secondary battery comprises a shell and an electrode assembly arranged in the shell, wherein the electrode assembly comprises a first pole piece, a second pole piece with opposite polarity to the first pole piece and a diaphragm, and the diaphragm is arranged between the adjacent first pole piece and second pole piece; The first pole piece comprises a first current collector and a first active material layer, the first active material layer is arranged on at least one side of the first current collector along the thickness direction of the first current collector, and the projection of the first active material layer falls into the projection range of the first current collector; The first current collector is provided with a first end face along a first direction, and the first direction is perpendicular to the thickness direction of the first current collector; The first end face is provided with a plurality of bulges, at least one part of the surfaces of the bulges are arc-shaped, the surface of the first end face is provided with a first layer of film, the first layer of film comprises metal oxide, the metal oxide in the first layer of film is at least one of alumina and copper oxide, and the first layer of film covers the bulges.
  2. 2. The secondary battery of claim 1, wherein the first end face is configured to be heat treated, the first active material layer has a second end face adjacent to the first end face in the first direction, the first end face and the second end face have a space therebetween, and the first current collector is a first nonfunctional area on which the first active material layer is not provided in a region between the first end face and the second end face.
  3. 3. The secondary battery according to claim 1, further comprising an electrolyte disposed within the case, the electrolyte comprising a first component selected from at least one of lithium tetrafluoroborate or lithium difluorophosphate, the mass ratio of the first component being M,0.1% +≤3%, based on the mass of the electrolyte.
  4. 4. The secondary battery of claim 1, wherein at least one edge end face of the first current collector is configured to be heat-treated in a direction perpendicular to a thickness direction of the first current collector, and/or the protrusions on the first end face are each arc-shaped, and the first layer film covers all the protrusions on the first end face.
  5. 5. The secondary battery according to claim 2, wherein the surface of the first nonfunctional area has a second layer of film including a metal oxide therein, the metal oxide in the second layer of film being selected from at least one of aluminum oxide, copper oxide, and cuprous oxide.
  6. 6. The secondary battery according to claim 2, wherein the second electrode sheet includes a second current collector and a second active material layer, the second active material layer being provided on a surface of the second current collector facing the adjacent first active material layer in a thickness direction of the second current collector, a projection of the second active material layer falling within a projection range of the second current collector; Along the first direction, a third end face is arranged on one side, close to the first end face, of the second current collector, a fourth end face is arranged on one side, close to the third end face, of the second active material layer, a second non-functional area is arranged in a region between the third end face and the fourth end face of the second current collector, and the second active material layer is not arranged on the second non-functional area; The third end face is configured to be heat-treated, and the second nonfunctional area does not overlap with the first nonfunctional area in the thickness direction of the electrode assembly.
  7. 7. The secondary battery according to claim 6, wherein the first electrode sheet is a negative electrode sheet, the second electrode sheet is a positive electrode sheet, the first electrode sheet covers the second electrode sheet in a thickness direction of the electrode assembly, the first active material layer includes silicon-based particles therein, the silicon-based particles include silicon-carbon particles including porous carbon, silicon particles at least partially located in an inner pore of the porous carbon, and a carbon layer at least partially located on a surface layer of the silicon-carbon particles; the silicon-based particles comprise silicon element and carbon element, the content of the silicon element is B percent, the content of the carbon element is C percent, and B/C is more than or equal to 0.7 and less than or equal to 1.3 based on the total mass of the silicon-based particles.
  8. 8. The secondary battery according to claim 6, wherein the first electrode sheet is a positive electrode sheet, the second electrode sheet is a negative electrode sheet, the second electrode sheet covers the first electrode sheet in a thickness direction of the electrode assembly, and the first active material layer includes lithium cobaltate.
  9. 9. The secondary battery according to any one of claims 6 to 8, wherein a minimum distance between the second end face and the fourth end face in the first direction is L1,0.1mm ∈l1 ∈3mm.
  10. 10. The secondary battery according to claim 8, wherein 0.2 mm≤L1≤2 mm.
  11. 11. The secondary battery according to claim 6, wherein the width of the first nonfunctional area in the first direction is R1,0< R1≤5 mm, and/or, Along the first direction, the width of the second nonfunctional area is R2,0< R2 is less than or equal to 5mm.
  12. 12. The secondary battery according to claim 6, wherein a first protection layer is provided on a surface of the first nonfunctional area in a thickness direction of the first current collector, and a material of the first protection layer includes ceramic; And/or, along the thickness direction of the first current collector, the first nonfunctional area surface comprises a first protective layer and a first primer layer which are arranged in a stacked manner, and the first primer layer is arranged between the first protective layer and the first current collector; And/or, along the thickness direction of the second current collector, a second protection layer is arranged on the surface of the second nonfunctional area, and the material of the second protection layer comprises ceramic; And/or, along the thickness direction of the second current collector, the surface of the second nonfunctional area comprises a second protective layer and a second primer layer which are arranged in a stacked manner, and the second primer layer is arranged between the second protective layer and the second current collector.
  13. 13. The secondary battery according to claim 5, wherein the first electrode sheet is a negative electrode sheet, the metal oxide in the first layer film comprises copper oxide, and the mass percentage of the copper oxide is W, W is equal to or more than 90% based on the mass of the first layer film; And/or the first electrode plate is a negative electrode plate, the metal oxide in the second layer film comprises cuprous oxide, the second layer film comprises at least one first area, and the mass percentage of the cuprous oxide is V which is more than or equal to 90% based on the mass of the first area; and/or the first pole piece is a positive pole piece, the metal oxide in the first layer film comprises aluminum oxide, and the mass percentage of the aluminum oxide is N, wherein N is more than or equal to 90% based on the mass of the first layer film; And/or the first pole piece is a positive pole piece, the metal oxide in the second layer film comprises aluminum oxide, the second layer film comprises at least one first area, and the mass percentage of the aluminum oxide is K, and the K is more than or equal to 90% based on the mass of the first area.
  14. 14. The secondary battery of claim 1, wherein the second electrode sheet comprises a straight portion and a bent portion, a plurality of straight portions are stacked along a second direction, the first electrode sheet is disposed between two adjacent straight portions, the bent portion is disposed along the first direction and connects two adjacent straight portions, the second electrode sheet is integrally bent and formed, the second direction is a thickness direction of the electrode assembly, and the second direction is perpendicular to the first direction.
  15. 15. A method for producing a secondary battery according to any one of claims 1 to 14, characterized by comprising: Cutting a first pole piece or cutting a current collector of the first pole piece to form a first pole lug, performing heat treatment on a first end face, wherein the first end face is one of a cutting face of the first pole piece or a cutting face of the first pole lug, and/or, And cutting the second pole piece or cutting a current collector of the second pole piece to form a second pole lug, wherein the current collector of the second pole piece is provided with a third end face along the first direction, the third end face is subjected to heat treatment, and the third end face is one of a cutting face of the second pole piece or a cutting face of the second pole lug.
  16. 16. The method for manufacturing a secondary battery according to claim 15, wherein the heat treatment is performed at a temperature of T, T being not less than 350 ℃.
  17. 17. An electronic device comprising the secondary battery according to any one of claims 1 to 14.

Description

Secondary battery, method for manufacturing secondary battery, and electronic device Technical Field The invention relates to the technical field of electrochemical energy storage, in particular to a secondary battery, a preparation method of the secondary battery and electronic equipment. Background Secondary batteries such as lithium ion batteries are widely applied to the fields of consumer electronics, electric automobiles, energy storage systems and the like due to the advantages of high energy density, long cycle life and the like, and the safety problem of the lithium ion batteries is also attracting more and more attention. Disclosure of Invention The applicant of the application finds through researches that burrs may be generated at the edges of a current collector of a pole piece when pole piece raw materials of the current secondary battery are used for cutting or trimming pole lugs, and the burrs of the pole piece may puncture or scratch a diaphragm in the subsequent assembly and charging and discharging processes of the secondary battery, so that safety problems such as short circuit risks and the like of the secondary battery are caused. In the charge and discharge process of the secondary battery, the root of the burr can be broken to generate free metal scraps due to repeated stress, so that the secondary battery has safety problems such as short circuit risk and the like. In view of the foregoing, it is necessary to provide a secondary battery, a method for manufacturing the secondary battery, and an electronic device for solving the safety problems such as short-circuit risk caused by burrs on the edge end surfaces of the pole pieces. The embodiment of the first aspect of the application provides a secondary battery, which comprises a shell and an electrode assembly arranged in the shell, wherein the electrode assembly comprises a first pole piece, a second pole piece and a diaphragm, the polarity of the second pole piece is opposite to that of the first pole piece, the diaphragm is arranged between the adjacent first pole piece and the second pole piece, the first pole piece comprises a first current collector and a first active material layer, the first active material layer is arranged on at least one side of the first current collector along the thickness direction of the first current collector, the projection of the first active material layer falls into the projection range of the first current collector, the first current collector is provided with a first end face along the first direction, the first direction is perpendicular to the thickness direction of the first current collector, a plurality of bulges are arranged on the first end face, at least part of surfaces of the bulges are arc-shaped, the first end face is provided with a first layer film, the metal oxide in the first layer film is arranged on the first layer film, and the metal oxide in the first layer film is selected from at least one of aluminum oxide and copper oxide, and the first layer film covers the bulges. When a pole piece of the secondary battery is cut or a tab is cut, burrs can be generated on the edge of a current collector of the pole piece, the burrs of the pole piece can puncture or scratch a diaphragm in the subsequent assembly and charging and discharging processes of the secondary battery, so that the secondary battery is at short circuit risk, and in the charging and discharging processes of the secondary battery, the root of the burrs can be broken to generate free metal fragments due to repeated stress, so that the secondary battery is at short circuit risk. At least part of the surface of at least one bulge on the first end face is arc-shaped, so that the possibility that the edge burrs of the first current collector pierce or scratch the diaphragm, free metal scraps are generated and short circuits are caused can be reduced. However, the arc-shaped bulge on the first end surface can repeatedly rub the diaphragm in a long-term charge and discharge process, so that the diaphragm is locally thinned, and a short circuit phenomenon is further caused. Compared with the metal in the first current collector, the metal oxide in the first layer film has better insulating property, so that the first layer film is arranged on the surface of the first end face, and the first layer film covers the protrusions of the first end face, so that the risk of short circuit can be further reduced, and the safety performance of the secondary battery is improved. In the subsequent process of assembling the secondary battery, the first end face can be protected, the wear resistance is improved, the possibility that the first end face is scratched to expose metal and generate metal scraps is reduced, and the possibility of micro short circuit in the secondary battery is reduced. In addition, the metal oxide in the first layer film also has better corrosion resistance, and in the charge and discharge process of the seco