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EP-4738521-A1 - ELECTROCHEMICAL DEVICE AND ELECTRONIC DEVICE

EP4738521A1EP 4738521 A1EP4738521 A1EP 4738521A1EP-4738521-A1

Abstract

This application provides an electrochemical device and an electronic device, where the electrochemical device includes an electrode assembly and an electrolyte, where the electrode assembly includes a negative electrode plate, the negative electrode plate includes a negative electrode active material layer, the negative electrode active material layer includes a negative electrode active material and a negative electrode binder, the negative electrode binder includes an ester substance and a non-ester substance, and based on a mass of the negative electrode binder, a mass percentage of the ester substance is x; the electrolyte includes fluoroethylene carbonate and a high-kinetic solvent, the high-kinetic solvent includes at least one of ethyl propionate, propyl propionate, or diethyl carbonate, and a ratio of a mass percentage of fluoroethylene carbonate to a mass percentage of the high-kinetic solvent in the electrolyte is y; and the electrochemical device satisfies: 17% ≤ x + y ≤ 53%, y is from 0.4% to 14%, and based on a mass of the electrolyte, a mass percentage of fluoroethylene carbonate is from 0.1% to 10%. By synergistically controlling x and y, this application mitigates volume expansion and capacity fade during cycling in fast-charging systems, thereby improving cycle performance.

Inventors

  • YAN, Dongyang

Assignees

  • Ningde Amperex Technology Limited

Dates

Publication Date
20260506
Application Date
20240522

Claims (11)

  1. An electrochemical device comprising an electrode assembly and an electrolyte, wherein the electrode assembly comprises a negative electrode plate, the negative electrode plate comprising a negative electrode active material layer, the negative electrode active material layer comprising a negative electrode active material and a negative electrode binder, and the negative electrode binder comprising an ester substance and a non-ester substance, wherein based on a mass of the negative electrode binder, a mass percentage of the ester substance is x; the electrolyte comprises fluoroethylene carbonate and a high-kinetic solvent, the high-kinetic solvent comprising at least one of ethyl propionate, propyl propionate, or diethyl carbonate, wherein a ratio of a mass percentage of fluoroethylene carbonate to a mass percentage of the high-kinetic solvent in the electrolyte is y; and the electrochemical device satisfies: 17% ≤ x + y ≤ 53%, y is from 0.4% to 14%, and based on a mass of the electrolyte, a mass percentage of fluoroethylene carbonate is from 0.1% to 10%.
  2. The electrochemical device according to claim 1, wherein the ester substance comprises at least one of isooctyl acrylate, isooctyl methacrylate, 1,3-propane sultone, diisocyanate, polyethylene glycol dimethyl ether acetate, methyl methacrylate, 2-ethylhexyl methacrylate, butyl acrylate, or phenolphthalein alcohol containing an ester group; and the non-ester substance comprises at least one of butadiene, acrylonitrile, styrene, acrylic acid, hydroxymethyl cellulose, polyacrylic acid, or adiponitrile.
  3. The electrochemical device according to claim 1, wherein the negative electrode binder comprises an acrylic substance, the acrylic substance comprising at least one of acrylic acid, acrylonitrile, isooctyl acrylate, isooctyl methacrylate, or butyl acrylate.
  4. The electrochemical device according to claim 1, wherein x is from 3% to 48%.
  5. The electrochemical device according to claim 1, wherein the electrochemical device satisfies at least one of the following: a) x is from 10% to 35%; b) y is from 3% to 13%; c) based on the mass of the electrolyte, a mass percentage of diethyl carbonate in the electrolyte is from 0% to 30%; d) based on a mass of the negative electrode active material layer, a mass percentage of the negative electrode binder is from 0.5% to 5%; e) a conductivity of the electrolyte is from 7 mS/cm to 11 mS/cm; and f) 17 % ≤ x + y ≤ 30 % .
  6. The electrochemical device according to claim 1, wherein the electrolyte further comprises at least one of ethyl difluoroacetate, ethylene carbonate, propylene carbonate, 1,3-propane sultone, ethylene glycol diethyl cyanide ether, butylene carbonate, dimethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, methyl butyrate, ethyl butyrate, γ-butyrolactone, δ-valerolactone, acetonitrile, succinonitrile, adiponitrile, glutaronitrile, 1,3,6-hexanetricarbonitrile, trans-hexenedinitrile, ethylene glycol bis(propionitrile) ether, or hexafluorocyclotriphosphazene.
  7. The electrochemical device according to claim 1, wherein the negative electrode binder comprises at least one of styrene-butadiene rubber, polyacrylic acid, polyvinyl acetate, or polyvinyl alcohol.
  8. The electrochemical device according to claim 1, wherein the negative electrode active material layer further comprises a negative electrode conductive agent and a dispersant, and based on a mass of the negative electrode active material layer, a mass percentage of the negative electrode active material is from 88% to 99%, a mass percentage of the negative electrode conductive agent is from 0% to 2%, and a mass percentage of the dispersant is from 0.5% to 5%.
  9. The electrochemical device according to claim 8, wherein the negative electrode active material comprises at least one of natural graphite, artificial graphite, lithium titanate, hard carbon, nano-silicon, silicon-carbon, or silicon-oxygen; the negative electrode conductive agent comprises at least one of conductive carbon spheres, acetylene black, conductive carbon black, Ketjen black, single-walled carbon nanotubes, multi-walled carbon nanotubes, nano-carbon fibers, graphene, or conductive graphite sheets; and the dispersant comprises at least one of lithium carboxymethyl cellulose, sodium carboxymethyl cellulose, or modified carboxymethyl cellulose.
  10. The electrochemical device according to claim 1, wherein the negative electrode active material comprises artificial graphite, wherein a ratio of a D-peak intensity to a G-peak intensity of the artificial graphite, as measured by Raman spectroscopy, is from 0.1 to 0.6.
  11. An electronic device comprising the electrochemical device according to any one of claims 1 to 10.

Description

This application claims priority to Chinese Patent Application No. 202310768103.1, filed on June 27, 2023 and entitled "ELECTROCHEMICAL DEVICE AND ELECTRONIC DEVICE", which is incorporated herein by reference in its entirety. TECHNICAL FIELD This application relates to the field of electrochemical technology, and more particularly, to an electrochemical device and an electronic device. BACKGROUND Electrochemical devices, such as lithium-ion secondary batteries, are widely used in fields such as smartphones, portable wearable devices, and electric vehicles due to their advantages of high energy density, high operating voltage, cycle stability, and environmental friendliness. With the continuous iterative development of consumer devices, market demands for increased charging speeds are rising, leading to an increased need for fast-charging lithium-ion secondary batteries. However, compared to traditional non-fast-charging systems, fast-charging systems exhibit more pronounced volume expansion and capacity fade during cycling. In view of this, improving the aforementioned issues in fast-charging systems and enhancing cycle performance have become urgent technical challenges for those skilled in the art. SUMMARY The purpose of this application is to provide an electrochemical device and an electronic device to address volume expansion and capacity fade issues during cycling in fast-charging systems, thereby improving cycle performance. The specific technical solution is as follows: According to a first aspect of this application, an electrochemical device is provided, including an electrode assembly and an electrolyte, where the electrode assembly includes a negative electrode plate, the negative electrode plate includes a negative electrode active material layer, the negative electrode active material layer includes a negative electrode active material and a negative electrode binder, the negative electrode binder includes an ester substance and a non-ester substance, and based on a mass of the negative electrode binder, a mass percentage of the ester substance is x; the electrolyte includes fluoroethylene carbonate (FEC) and a high-kinetic solvent, the high-kinetic solvent includes at least one of ethyl propionate (EP), propyl propionate (PP), or diethyl carbonate (DEC), and a ratio of a mass percentage of FEC to a mass percentage of the high-kinetic solvent in the electrolyte is y; and the electrochemical device satisfies: 17% ≤ x + y ≤ 53%, y is from 0.4% to 14%, and based on a mass of the electrolyte, a mass percentage of FEC is from 0.1% to 10%. Through in-depth research, the inventor of this application has found that optimizing the combination of the negative electrode plate and the electrolyte formulation, and synergistically controlling x and y to satisfy the above relationship, can mitigate volume expansion and capacity fade issues during cycling in fast-charging systems, thereby improving cycle performance. In some embodiments of this application, the ester substance includes at least one of isooctyl acrylate, isooctyl methacrylate, 1,3-propane sultone, diisocyanate, polyethylene glycol dimethyl ether acetate, methyl methacrylate, 2-ethylhexyl methacrylate, butyl acrylate, or phenolphthalein alcohol containing an ester group; and the non-ester substance includes at least one of butadiene, acrylonitrile, styrene, acrylic acid, hydroxymethyl cellulose, polyacrylic acid, or adiponitrile. In some embodiments of this application, the negative electrode binder includes an acrylic substance, the acrylic substance including at least one of acrylic acid, acrylonitrile, isooctyl acrylate, isooctyl methacrylate, or butyl acrylate. In some embodiments of this application, x is from 3% to 48%. By controlling the mass percentage of the ester substance in the negative electrode binder within the above range, volume expansion and capacity fade issues during cycling in fast-charging systems can be further mitigated, thereby improving cycle performance. In some embodiments of this application, the electrochemical device satisfies at least one of the following: a) x is from 10% to 35%; b) y is from 3% to 13%; c) based on the mass of the electrolyte, a mass percentage of DEC in the electrolyte is from 0% to 30%; d) based on a mass of the negative electrode active material layer, a mass percentage of the negative electrode binder is from 0.5% to 5%; e) a conductivity of the electrolyte is from 7 mS/cm to 11 mS/cm; and f) 17% ≤ x + y ≤ 30%. By controlling the above parameters, volume expansion and capacity fade issues during cycling in fast-charging systems can be further mitigated, thereby improving cycle performance. In some embodiments of this application, the electrolyte further includes at least one of ethyl difluoroacetate, ethylene carbonate (EC), propylene carbonate (PC), 1,3-propane sultone (PS), ethylene glycol diethyl cyanide ether, butylene carbonate, dimethyl carbonate, ethyl methyl carbonate, methyl propyl