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CN-117039122-B - Battery cell

CN117039122BCN 117039122 BCN117039122 BCN 117039122BCN-117039122-B

Abstract

The invention discloses a battery. In the battery, the positive plate comprises a positive smooth section and a positive curved section, and the negative plate comprises a negative smooth section and a negative curved section. The half-electricity rebound rate alpha 21 of the anode bending section is 1.5% -7% greater than the half-electricity rebound rate alpha 11 of the anode smoothing section, and/or the full-electricity rebound rate alpha 22 of the anode bending section is 6% -8% greater than the full-electricity rebound rate alpha 12 of the anode smoothing section. According to the invention, the rebound rate of the negative electrode bending section and the rebound rate of the negative electrode smooth section are controlled within a certain range, so that the problem that the rebound rate of the bending section is not matched with the rebound rate of the straight section due to overlarge rebound of the bending section can be prevented, the thickness expansion rate of the negative electrode plate in the charging process can be effectively relieved, the rebound rate difference between the negative electrode bending section and the negative electrode smooth section is reduced, the electrode plate is ensured not to deform under stress, the capacity attenuation and powder dropping problems caused by overlarge negative electrode expansion in the battery core circulation process are favorably eliminated, and the consistency of the battery core circulation is ensured.

Inventors

  • Liang Feipan
  • WANG DI
  • CHEN TIANTIAN
  • ZHANG SHUANGHU
  • ZHANG JINGYAN
  • Quan Xiaoqian
  • XIE JICHUN

Assignees

  • 珠海冠宇电池股份有限公司

Dates

Publication Date
20260512
Application Date
20230914

Claims (7)

  1. 1. A battery comprises a positive plate and a negative plate, wherein the negative plate comprises a negative current collector and a negative active material layer arranged on the surface of the negative current collector, the negative active material layer comprises a dispersing agent, and polar functional groups in the dispersing agent comprise at least two of-CN, -OH, -COOH, -COOR and-NH 2 ; The positive plate and the negative plate are sequentially overlapped and form a winding core through a winding process, wherein in the winding core, the positive plate comprises a positive smooth section and a positive bending section, and the negative plate comprises a negative smooth section and a negative bending section; the positive electrode smooth section is a flat area in a plane state in the positive electrode plate of the coiled core battery, the positive electrode bent section is a bending area in a semicircular arc state due to bending in the positive electrode plate of the coiled core battery, the negative electrode smooth section is a flat area in a plane state in the negative electrode plate of the coiled core battery, and the negative electrode bent section is a bending area in a semicircular arc state due to bending in the negative electrode plate of the coiled core battery; the method is characterized in that: The half-electricity rebound rate alpha 21 of the negative electrode bending section is 1.5% -7% larger than the half-electricity rebound rate alpha 11 of the negative electrode smoothing section; The full-charge rebound rate alpha 22 of the negative electrode bending section is 6% -8% greater than the full-charge rebound rate alpha 12 of the negative electrode smoothing section; The half-electric rebound rate alpha 11 of the negative electrode smooth section is in the range of 11.0 percent to less than or equal to alpha 11 and less than or equal to 16.5 percent, and the half-electric rebound rate alpha 21 of the negative electrode smooth section is in the range of 13.5 percent to less than or equal to alpha 21 and less than or equal to 21.5 percent; The full-charge rebound rate alpha 12 of the negative electrode smooth section is in the range of 18.0 percent to less than or equal to alpha 12 percent to less than or equal to 21.0 percent, and the full-charge rebound rate alpha 22 of the negative electrode smooth section is in the range of 23.0 percent to less than or equal to alpha 22 to less than or equal to 28.0 percent.
  2. 2. The battery of claim 1, wherein the positive electrode smooth segment has a half-electric bounce rate β 11 in the range of 2.0% to β 11 to 6.5%, and the positive electrode curved segment has a half-electric bounce rate β 21 in the range of 5.0% to β 21 to 11.0%.
  3. 3. The battery of claim 1, wherein the positive electrode smooth segment has a full-charge bounce rate β 12 in the range of 6.0% to β 12 to 11.1%, and the positive electrode curved segment has a full-charge bounce rate β 22 in the range of 15.0% to β 22 to 18.0%.
  4. 4. The battery of claim 1, wherein a ratio Θ 11 of the half-electric bounce rate α 11 of the negative electrode smooth segment and the half-electric bounce rate β 11 of the positive electrode smooth segment ranges from 2 ∈Θ 11 ∈9.
  5. 5. The battery of claim 1, wherein the ratio Θ 12 of the half-electric bounce rate α 21 of the negative curved segment and the half-electric bounce rate β 21 of the positive curved segment ranges from 1.5 ∈Θ 12 ∈4.
  6. 6. The battery of claim 1, wherein the ratio Θ 21 of the full charge bounce rate α 12 of the negative electrode smooth segment to the full charge bounce rate β 12 of the positive electrode smooth segment is in the range 1.5 ∈Θ 21 ∈3.5.
  7. 7. The battery of claim 1, wherein the ratio Θ 22 of the full charge bounce rate α 22 of the negative curved segment to the full charge bounce rate β 22 of the positive curved segment is in the range 1.3 ∈Θ 22 ∈2.

Description

Battery cell Technical Field The invention relates to the technical field of battery preparation, in particular to a battery. Background Along with the continuous improvement of market demands, lithium ion batteries become mainstream products with the characteristics of high energy density, long service life, excellent multiplying power performance, environmental protection and the like. Consumer batteries and power batteries are both faced with high capacity and other requirements, which require high battery energy density. The positive and negative electrode sheets are the main components of the battery core, and in the rolled core battery, the negative electrode sheet generally comprises a negative electrode smooth section (namely, a flat area in a plane state in the rolled core battery negative electrode sheet) and a negative electrode bending section (namely, a bending area in a semicircular arc state due to bending in the rolled core battery negative electrode sheet), and the positive electrode sheet generally comprises a positive electrode smooth section (namely, a flat area in a plane state in the rolled core battery positive electrode sheet) and a positive electrode bending section (namely, a bending area in a semicircular arc state due to bending in the rolled core battery positive electrode sheet). The rebound rate of the bending section of the positive electrode plate and the negative electrode plate is over high relative to that of the smooth section, so that stress is easily generated, namely the stress of the bending section is over high, and the active material layer of the bending section is cracked. In addition, in the battery charging process, the rebound of the bending section of the negative plate is too large, so that the thickness expansion rate of the negative plate is too large, the forced deformation of the plate is serious, the capacity attenuation and powder dropping are easy to occur, and the consistency of the battery core circulation is difficult to ensure. Disclosure of Invention In view of the above, an object of the present invention is to provide a battery in which the difference between the rebound rate of the negative electrode curved section and the rebound rate of the negative electrode smooth section is reduced by controlling the rebound rate of the negative electrode curved section and the rebound rate of the negative electrode smooth section within a certain range, thereby solving the problems such as cracking of the active material layer of the curved section due to excessive stress in the positive and negative electrode sheet curved sections. In order to achieve the above purpose, the present invention provides the following technical solutions: A battery, includes positive plate and negative plate, positive plate includes positive smooth section and positive crooked section, negative plate includes negative smooth section and negative crooked section, wherein: The half-electricity rebound rate alpha 21 of the negative electrode bending section is 1.5% -7% larger than the half-electricity rebound rate alpha 11 of the negative electrode smoothing section; And/or, the full-charge bounce rate alpha 22 of the negative electrode bending section is 6% -8% greater than the full-charge bounce rate alpha 12 of the negative electrode smoothing section. Alternatively, in the above battery, the half-electric bounce rate α 11 of the anode smooth segment ranges from 11.0% to 16.5% and the half-electric bounce rate α 21 of the anode curved segment ranges from 13.5% to 21.5%. Alternatively, in the above battery, the half-electric rebound rate β 11 of the positive electrode smooth section ranges from 2.0% to 11 to 6.5%, and the half-electric rebound rate β 21 of the positive electrode curved section ranges from 5.0% to 21 to 11.0%. Alternatively, in the above battery, the full-charge bounce rate α 12 of the anode smooth segment is in the range of 18.0% or less than or equal to α 12 or less than or equal to 21.0%, and the full-charge bounce rate α 22 of the anode curved segment is in the range of 23.0% or less than or equal to α 22 or less than or equal to 28.0%. Alternatively, in the above battery, the full-charge bounce rate β 12 of the positive electrode smooth section is in the range of 6.0% to β 12 to 11.1%, and the full-charge bounce rate β 22 of the positive electrode curved section is in the range of 15.0% to β 22 to 18.0%. Optionally, in the above battery, a ratio Θ 11 of the half-electric bounce rate α 11 of the negative electrode smooth section and the half-electric bounce rate β 11 of the positive electrode smooth section ranges from 2 Θ 11 to 9. Optionally, in the above battery, a ratio Θ 12 of a half-electric bounce rate α 21 of the negative electrode bending section and a half-electric bounce rate β 21 of the positive electrode bending section ranges from 1.5 Θ 12 to 4. Optionally, in the above battery, a ratio Θ 21 of a full-charge bounce rate α 12 of the negative e