CN-122026026-A - Negative electrode plate, electrode plate processing method, secondary battery and electronic equipment

Abstract

The application provides a negative pole piece, a pole piece processing method, a secondary battery and electronic equipment. The negative electrode plate comprises a first current collector and a first active material layer, wherein 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 active material layer comprises silicon-based particles, a plurality of bulges are arranged on the first end face, at least part of the surface of at least one bulge is arc-shaped, and the first direction is perpendicular to the thickness direction of the first current collector. The possibility that the protrusion on the first end face pierces or breaks the diaphragm to cause a short circuit is reduced, and the safety performance of the secondary battery is improved while the energy density of the secondary battery is improved.

Inventors

• CHI JINFENG

Assignees

• 宁德新能源科技有限公司

Dates

Publication Date

20260512

Application Date

20260410

Claims (18)

1. 1. A negative electrode plate is characterized in that, The negative electrode plate 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; Along a first direction, the first current collector is provided with a first end face, the first active material layer comprises silicon-based particles, a plurality of bulges are arranged on the first end face, at least one part of surfaces of the bulges are arc-shaped, and the first direction is perpendicular to the thickness direction of the first current collector.
2. 2. The negative electrode tab of claim 1, wherein the first end surface has a first layer of film comprising a metal oxide therein, the metal oxide in the first layer of film being selected from at least one of copper oxide or cuprous oxide.
3. 3. The negative electrode tab of claim 1 wherein the first end surface has a maximum height roughness Rz of 20um or less.
4. 4. The negative electrode tab of claim 2, wherein at least one edge 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 wherein the protrusions on the first face are each arc-shaped.
5. 5. The negative electrode tab of claim 4, wherein, in the first direction, the first active material layer has a second end face adjacent to the first end face, the first current collector being a first nonfunctional area in a region between the first end face and the second end face, the first nonfunctional area having no first active material layer disposed thereon; Along the first direction, the distance between the first end face and the second end face is Lmm, and the mass percentage content of silicon element is N%, and N multiplied by L is more than or equal to 10 and less than or equal to 500 based on the mass of the first active material layer.
6. 6. The negative electrode tab of claim 5, wherein the negative electrode tab meets at least one of: (1)2≤N≤40; (2)L≥8; (3)L≤12。
7. 7. the negative electrode tab of claim 1 wherein the silicon-based particles comprise silicon-carbon particles comprising porous carbon, silicon particles at least partially within the pores within the porous carbon, and a carbon layer at least partially on the surface 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 negative electrode sheet according to claim 1, wherein the first active material layer includes a first region and a second region, the first region being closer to the first end face than the second region in a direction perpendicular to a thickness direction of the first current collector, the binder content in the first region being M based on a mass of the negative electrode material in the first region, the binder content in the second region being n≤n based on a mass of the negative electrode material in the second region.
9. 9. The negative electrode of claim 8, wherein N-M is 1% or more.
10. 10. The negative electrode tab of claim 1, wherein the first current collector has opposing first and second surfaces along a thickness direction of the first current collector, and wherein a junction of the first end surface with the first and/or second surfaces is arcuate.
11. 11. The negative electrode of claim 5, wherein the first nonfunctional area surface has a second layer of film comprising a metal oxide selected from at least one of copper oxide or cuprous oxide, the negative electrode satisfying at least one of: (1) The first layer film comprises copper oxide, and the mass percentage of the copper oxide is W which is more than or equal to 90 percent based on the mass of the first layer film; (2) The second layer film comprises at least one third region, cuprous oxide is contained in the third region, and/or the mass percentage of the cuprous oxide is V which is more than or equal to 90% based on the mass of the third region.
12. 12. The negative electrode of claim 5, wherein the first nonfunctional area is provided with a protective layer, the protective layer comprising a ceramic.
13. 13. The negative electrode tab of claim 1, wherein the first current collector comprises a first tab extending in the first direction, and the first end face is a surface of the first tab in a direction perpendicular to a thickness direction of the first current collector.
14. 14. A pole piece treatment method for treating the negative pole piece according to any one of claims 1 to 13, characterized by comprising: And cutting the negative electrode plate or cutting a current collector of the negative electrode plate to form a first tab, and performing heat treatment on a first end face, wherein the first end face is one of a cutting face of the negative electrode plate or a cutting face of the first tab.
15. 15. The pole piece treatment method of claim 14, wherein the heat treatment is performed at a temperature of T, T being greater than or equal to 350 ℃.
16. 16. A secondary battery comprising the negative electrode tab of any one of claims 1 to 13.
17. 17. The secondary battery according to claim 16, wherein the secondary battery includes positive electrode tabs, the positive electrode tabs and the negative electrode tabs being alternately stacked.
18. 18. An electronic device comprising the secondary battery as claimed in claim 16 or 17.

Description

Negative electrode plate, electrode plate processing method, secondary battery and electronic equipment Technical Field The invention relates to the technical field of electrochemical energy storage, in particular to a negative pole piece, a pole piece processing method, a secondary battery and electronic equipment. Background Secondary batteries such as lithium ion batteries are widely used in the fields of consumer electronics, electric vehicles, energy storage systems and the like due to their advantages such as high energy density and long cycle life. The negative electrode plate is used as a key component of the secondary battery, and the performance of the negative electrode plate directly influences the overall performance of the battery. The traditional negative electrode plate generally adopts graphite as an active substance, but the theoretical capacity of the graphite is limited, and the increasing requirement of high energy density is difficult to meet. 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 negative electrode plate when the current negative electrode plate raw material cuts or cuts a tab, and the burrs of the negative electrode plate may puncture or scratch a diaphragm during the subsequent assembly and charging and discharging processes of the secondary battery, so that the secondary battery generates safety problems such as short circuit risks and the like. In view of the foregoing, it is necessary to provide a negative electrode tab, a tab processing method, a secondary battery, and an electronic device, so as to solve the safety problems such as short circuit risk caused by burrs on the edge end surface of the negative electrode tab. The embodiment of the first aspect of the application provides a negative electrode plate, which comprises a first current collector and a first active material layer, wherein 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 active material layer comprises silicon-based particles, a plurality of bulges are arranged on the first end face, at least part of the surface of at least one bulge is arc-shaped, and the first direction is perpendicular to the thickness direction of the first current collector. The theoretical capacity of silicon is far higher than that of a traditional graphite anode material, but the silicon can generate larger internal stress and deformation in the charge and discharge process of the battery, so that the position deviation of the edge of the first current collector is caused, the possibility of short circuit caused by the burr bulge on the first end surface is higher, and therefore, at least part of the surface of at least one bulge on the first end surface is arc-shaped through heat treatment or other modes on the burr bulge on the first end surface, the possibility that the bulge on the first end surface pierces or breaks a diaphragm to cause short circuit is reduced, and the safety performance of the secondary battery is improved while the energy density of the secondary battery is improved. In addition, if the burrs on the first end face are subjected to heat treatment, the first active material layer is inevitably affected by high temperature during heat treatment, and negative active materials such as traditional graphite materials and the like can undergo irreversible oxidation reaction under high-temperature burning to generate gas and consume carbon elements so as to reduce the capacity of the graphite, and on the other hand, the crystal structure of the graphite can be irreversibly disturbed due to high temperature, so that the capability of lithium ion intercalation and deintercalation of the graphite is reduced. The silicon-based particles are better in overall high temperature resistance, a layer of extremely thin and compact silicon dioxide (SiO 2) passivation layer can be formed on the surface of the silicon-based particles rapidly at high temperature, the silicon in the silicon-based particles can be effectively prevented from being further oxidized, and the internal structure of the silicon-based particles is not easily influenced due to the fact that the silicon self-melting point is high. More importantly, the SiO 2 passivation layer generated on the surface of the silicon-based particles can be partially reduced in the first charge and discharge process of the battery and react with electrolyte to form a solid electrolyte interface film (SEI film). The SEI film generated at this time is denser and more stable than the SEI film formed under the conventional conditions, and helps to suppress