Search

CN-121983641-A - Battery cell, battery device and electricity utilization device

CN121983641ACN 121983641 ACN121983641 ACN 121983641ACN-121983641-A

Abstract

The application provides a battery cell, a battery device and an electric device, wherein the battery cell comprises a positive electrode plate, a separation film, a negative electrode plate and electrolyte, the positive electrode plate and the negative electrode plate are arranged in a laminated mode, the separation film is arranged between the positive electrode plate and the negative electrode plate, the positive electrode plate comprises a positive electrode main body part and a positive electrode lug part, the ratio of the long side size to the short side size of the positive electrode main body part is (3-8): 1, the negative electrode plate comprises a negative electrode main body part and a negative electrode lug part, the long side of the negative electrode main body part exceeds the long side edge of the positive electrode main body part by 2 mm-9 mm, the long side of the separation film exceeds the long side edge of the negative electrode main body part by 2 mm-10 mm, the electrolyte comprises a solvent, the solvent comprises one or more of dimethyl carbonate and linear carboxylic acid esters with structures shown in the formula (1), and R 1 、R 2 in the formula (1) respectively independently comprises C1-C5 alkyl or halogenated alkyl. The battery monomer has higher energy density, better cycle performance and lower self-discharge.

Inventors

  • WEI XICHEN
  • LUO YUYING
  • ZHAO YUZHEN
  • Dai Xiaoshan
  • LIN CHENHUI

Assignees

  • 宁德时代新能源科技股份有限公司

Dates

Publication Date
20260505
Application Date
20250620

Claims (20)

  1. 1. The laminated battery cell is characterized by comprising a soft package shell, a positive electrode plate, an isolating film, a negative electrode plate and electrolyte, wherein the positive electrode plate and the negative electrode plate are arranged in a laminated manner, the isolating film is arranged between the positive electrode plate and the negative electrode plate, and the positive electrode plate, the isolating film, the negative electrode plate and the electrolyte are arranged in the soft package shell; The positive electrode plate comprises a positive electrode main body part and a positive electrode lug part connected with the positive electrode main body part, and the ratio of the long side size to the short side size of the positive electrode main body part is (3-8): 1; The negative electrode plate comprises a negative electrode main body part and a negative electrode lug part connected with the negative electrode main body part, wherein the long side of the negative electrode main body part exceeds the long side edge of the positive electrode main body part by 2 mm-9 mm, and the long side of the isolating film exceeds the long side edge of the negative electrode main body part by 2 mm-10 mm; the electrolyte comprises a first solvent, wherein the first solvent comprises one or more of dimethyl carbonate and linear carboxylic ester with a structure shown in a formula (1); r 1 -（C=O）-O-R 2 formula (1); Wherein R 1 、R 2 each independently comprises a C1-C5 alkyl or haloalkyl.
  2. 2. The laminated battery cell according to claim 1, wherein the ratio of the long side dimension to the short side dimension of the positive electrode main body portion is (4 to 6): 1.
  3. 3. The laminated battery cell according to claim 1 or 2, wherein the long side of the negative electrode main body portion exceeds the long side edge of the positive electrode main body portion by 3mm to 6mm, and/or the long side of the separator exceeds the long side edge of the negative electrode main body portion by 3mm to 7mm.
  4. 4. The laminated battery cell of any one of claims 1-3, wherein the linear carboxylic acid ester comprises one or more of ethyl acetate, methyl propionate, propyl acetate, ethyl formate, and isopropyl formate.
  5. 5. The laminated battery cell according to any one of claims 1 to 4, wherein the mass fraction of the first solvent is 10% to 60% based on the mass of the electrolyte.
  6. 6. The laminated battery cell of claim 5, wherein the first solvent is 15% -35% by mass of the electrolyte.
  7. 7. The laminated battery cell according to any one of claims 1 to 6, wherein the electrolyte has a conductivity of 10mS/cm to 16mS/cm at normal temperature.
  8. 8. The laminated battery cell according to any one of claims 1 to 7, wherein the electrolyte further comprises a lithium salt, the lithium salt comprises one or more of lithium hexafluorophosphate and lithium difluorosulfimide, and the total mass fraction of the lithium hexafluorophosphate and/or the lithium difluorosulfimide is 12% -18% based on the mass of the electrolyte.
  9. 9. The laminated battery cell according to claim 8, wherein the mass ratio of the lithium hexafluorophosphate to the lithium difluorosulfonimide is (1.2-3): 1.
  10. 10. The laminated battery cell of any one of claims 1-9, wherein the electrolyte further comprises an additive comprising one or more of vinylene carbonate, fluoroethylene carbonate, and 1, 3-propane sultone.
  11. 11. The laminated battery cell of claim 10, wherein the additive is less than or equal to 5% by mass of the electrolyte.
  12. 12. The laminated battery cell according to claim 11, wherein the mass fraction of the additive is 0.5% -3% based on the mass of the electrolyte.
  13. 13. The laminated battery cell according to any one of claims 1 to 12, wherein the positive electrode tab portion is connected to a short side of the positive electrode main body portion, and the negative electrode tab portion is connected to a short side of the negative electrode main body portion.
  14. 14. The laminated battery cell of any one of claims 1-13, wherein the bladder housing has a thickness of 70 μιη to 200 μιη.
  15. 15. The laminated battery cell of any one of claims 1-14, wherein the negative body portion comprises a negative current collector and a negative film layer, the negative film layer comprising a first negative film layer and a second negative film layer disposed on the negative current collector, the first negative film layer being located between the negative current collector and the second negative film layer; The first negative electrode film layer and the second negative electrode film layer both comprise graphite, the average value of the longest diameters of the graphite in the first negative electrode film layer is 7-18 microns, the average value of the longest diameters of the graphite in the second negative electrode film layer is 6-10 microns, and the average value of the longest diameters of the graphite in the first negative electrode film layer is larger than the average value of the longest diameters of the graphite in the second negative electrode film layer.
  16. 16. The laminated battery cell of claim 15, wherein the graphite in the first and second negative electrode film layers each independently comprises a graphite particle body and an amorphous carbon coating layer provided on a surface of the graphite particle body, the amorphous carbon coating layer having a thickness of 100nm to 500nm.
  17. 17. The laminated battery cell of claim 15 or 16, wherein the graphitization degree of the graphite in the first and second negative electrode film layers is 90% -94% each independently.
  18. 18. The laminated battery cell of any one of claims 15-17, wherein the negative film layer has a single-sided coated surface density of 0.13g/1540.25mm 2 ~0.22g/1540.25mm 2 .
  19. 19. The laminated battery cell of any one of claims 1-18, wherein the negative electrode sheet has a compacted density of 1.3g/cc to 1.52g/cc.
  20. 20. The laminated battery cell according to any one of claims 1 to 19, wherein the positive electrode main body portion includes a positive electrode current collector and a positive electrode film layer provided on the positive electrode current collector, the positive electrode film layer includes a lithium-containing transition metal phosphate including one or more of 200ppm to 2500ppm by mass of aluminum element, 300ppm to 2000ppm by mass of vanadium element, and 1500ppm by mass of titanium element.

Description

Battery cell, battery device and electricity utilization device The application is a divisional application of patent application of which the application date is 2025, 06 and 20, the application number is 202510831242.3, and the application is named as battery cell, battery device and power utilization device. Technical Field The application relates to the technical field of batteries, in particular to a battery cell, a battery device and an electricity utilization device. Background In recent years, as the application range of secondary batteries is becoming wider, secondary batteries are widely used in energy storage power systems such as hydraulic power, thermal power, wind power and solar power stations, and in various fields such as electric tools, electric bicycles, electric motorcycles and electric automobiles. As secondary batteries have been greatly developed, higher demands are also being made on the performance of the secondary batteries. It is one of the important directions of those skilled in the art to find a battery having a high energy density and being capable of having both a good cycle performance and a low self-discharge. Disclosure of Invention The present application has been made in view of the above problems, and an object of the present application is to provide a battery cell having a high energy density, good cycle performance, and low self-discharge, a battery device, and an electric device. In order to achieve the above object, a first aspect of the present application provides a battery cell, including a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte, where the positive electrode sheet and the negative electrode sheet are stacked, and the separator is disposed between the positive electrode sheet and the negative electrode sheet; The positive electrode plate comprises a positive electrode main body part and a positive electrode lug part connected with the positive electrode main body part, and the ratio of the long side size to the short side size of the positive electrode main body part is (3-8): 1; The negative electrode plate comprises a negative electrode main body part and a negative electrode lug part connected with the negative electrode main body part, wherein the long side of the negative electrode main body part exceeds the long side edge of the positive electrode main body part by 2 mm-9 mm, and the long side of the isolating film exceeds the long side edge of the negative electrode main body part by 2 mm-10 mm; the electrolyte comprises a first solvent, wherein the first solvent comprises one or more of dimethyl carbonate and linear carboxylic ester with a structure shown in a formula (1); r 1-（C=O）-O-R2 formula (1); Wherein R 1、R2 each independently comprises a C1-C5 alkyl or haloalkyl. The ratio of the long side size to the short side size of the positive electrode main body part of the positive electrode plate is controlled to be (3-8): 1, and when the positive electrode plate with the larger length-width ratio is adopted to form a laminated battery, the battery space occupied by the lug part is relatively less, so that the energy density of a battery cell is improved. By adopting one or more of dimethyl carbonate and linear carboxylic ester with a structure shown in a formula (1) as a solvent in the electrolyte, the solvent has lower viscosity and is beneficial to improving the conductivity of the electrolyte, and the problem of insufficient electrolyte infiltration in the laminated battery with a larger pole piece length-width ratio can be solved, so that the battery unit can have better cycle performance. By adopting specific overhang settings in the negative electrode plate and the isolating film, the long side of the negative electrode main body part exceeds the long side edge of the positive electrode main body part by2 mm-9 mm, the long side of the isolating film exceeds the long side edge of the negative electrode main body part by2 mm-10 mm, and the self-discharge of the battery caused by dislocation of the positive electrode plate and the negative electrode plate due to gas production of a low-viscosity solvent can be well reduced, so that the battery monomer can realize lower self-discharge. The battery monomer has higher energy density, better cycle performance and lower self discharge through the synergistic combination of the factors by arranging the length-width ratio of the pole piece, the electrolyte solvent and overhang of the negative pole piece and the isolating film. In any embodiment, the ratio of the long side dimension to the short side dimension of the positive electrode main body is (4 to 6): 1. Thus, the battery unit can better give consideration to higher energy density, better cycle performance and lower self discharge. In any embodiment, the long side of the negative electrode main body part exceeds the long side edge of the positive electrode main body part by 3-6 mm, and the long side of th