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DE-212026000007-U1 - Battery cell, battery device and power-consuming device

DE212026000007U1DE 212026000007 U1DE212026000007 U1DE 212026000007U1DE-212026000007-U1

Abstract

Battery cell comprising a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte solution, wherein the positive electrode sheet, the separator, and the negative electrode sheet are arranged in alternating stacks; wherein the positive electrode sheet comprises a positive electrode current collector and a positive electrode active layer arranged on at least one side of the positive electrode current collector, wherein the negative electrode sheet comprises a negative electrode current collector and a negative electrode active layer arranged on at least one side of the negative electrode current collector, the positive electrode active layer containing primary particles of lithium iron phosphate; wherein the separator comprises a base film and a bonding layer, the bonding layer being a porous continuous structure, the bonding layer being arranged on at least one side of the base film facing the positive electrode active layer; wherein the electrolyte solution comprises a first solvent, wherein the first solvent comprises one or more of dimethyl carbonate and linear carboxylic acid ester, wherein a structural formula of the linear carboxylic acid ester is R 1 -COO-R 2 , wherein R 1 and R 2 each independently comprise a C1 to C5 alkyl group or a halogenated C1 to C5 alkyl group.

Assignees

  • CONTEMPORARY AMPEREX TECHNOLOGY CO LTD

Dates

Publication Date
20260513
Application Date
20260128
Priority Date
20250620

Claims (20)

  1. Battery cell comprising a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte solution, wherein the positive electrode sheet, the separator, and the negative electrode sheet are arranged in alternating stacks; wherein the positive electrode sheet comprises a positive electrode current collector and a positive electrode active layer arranged on at least one side of the positive electrode current collector, wherein the negative electrode sheet comprises a negative electrode current collector and a negative electrode active layer arranged on at least one side of the negative electrode current collector, the positive electrode active layer containing primary particles of lithium iron phosphate; wherein the separator comprises a base film and a bonding layer, the bonding layer being a porous continuous structure, the bonding layer being arranged on at least one side of the base film facing the positive electrode active layer; wherein the electrolyte solution comprises a first solvent, wherein the first solvent comprises one or more of dimethyl carbonate and linear carboxylic acid ester, wherein a structural formula of the linear carboxylic acid ester is R 1 -COO-R 2 , wherein R 1 and R 2 each independently comprise a C1 to C5 alkyl group or a halogenated C1 to C5 alkyl group.
  2. Battery cell after Claim 1 , wherein the thickness of the bonding layer on a single side is 0.5 µm to 2.5 µm and optionally 1 µm to 2.5 µm.
  3. Battery cell after Claim 1 or 2 , where the porosity of the separator is 40% to 60%.
  4. Battery cell after one of the Claims 1 until 3 , wherein the bonding layer comprises one or more of polyvinylidene fluoride and polyvinylidene fluoride-hexafluoropropylene copolymer.
  5. Battery cell after one of the Claims 1 until 4 , wherein the separator further comprises an inorganic ceramic layer, the inorganic ceramic layer being arranged between the base film and the bonding layer.
  6. Battery cell after Claim 5 , wherein the inorganic ceramic layer contains one or more of aluminium oxide, silicon oxide and boehmite.
  7. Battery cell after one of the Claims 1 until 6 , where the average particle size of the primary lithium iron phosphate particles is 100 nm to 800 nm.
  8. Battery cell after Claim 7 , where the average particle size of the primary lithium iron phosphate particles is 500 nm to 800 nm.
  9. Battery cell after one of the Claims 1 until 8 , wherein the primary lithium iron phosphate particles contain a doped or undoped lithium iron phosphate material, wherein a doping element comprises one or more of Al, V and Ti.
  10. Battery cell after one of the Claims 1 until 9 , where the conductivity of the electrolyte solution under room temperature conditions is 9.5 ms/cm to 18 ms/cm.
  11. Battery cell after one of the Claims 1 until 10 , wherein, based on the mass of the electrolyte solution, the mass percentage of the first solvent is 10% to 60% and optionally 15% to 35%.
  12. Battery cell after one of the Claims 1 until 11 , wherein the electrolyte solution further comprises a lithium salt, wherein the lithium salt comprises lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide, wherein the mass ratio of lithium hexafluorophosphate to lithium bis(fluorosulfonyl)imide is (1,2-3):1.
  13. Battery cell after Claim 12 , wherein, based on the mass of the electrolyte solution, the mass percentage of the lithium salt is 12% to 18%.
  14. Battery cell after one of the Claims 1 until 13 , wherein the electrolyte solution further comprises an additive, wherein the additive comprises one or more of vinylene carbonate, fluoroethylene carbonate and 1,3-propanesultone.
  15. Battery cell after Claim 14 , wherein, based on the mass of the electrolyte solution, the mass percentage of the additive is 0.1% to 5%.
  16. Battery cell after one of the Claims 1 until 15 , wherein the negative electrode active layer comprises a first active layer and a second active layer, wherein the first active layer is arranged between the negative electrode current collector and the second active layer, wherein the first active layer comprises first graphite, wherein the second active layer comprises second graphite, wherein the average value of the longest diameter of the first graphite is 7 µm to 18 µm, the average value of the longest diameter of the second graphite is 6 µm to 10 µm, and the average value of the longest diameter of the first graphite is greater than the average value of the longest diameter of the second graphite.
  17. Battery cell after Claim 16 , wherein the first graphite and the second graphite each independently comprise a graphite particle body and an amorphous carbon coating layer arranged on a surface of the graphite particle body, wherein the thickness of the amorphous carbon coating layer is 100 nm to 500 nm; and/or the volume-averaged particle size Dv50 of the first graphite and the second graphite each independently is 7 µm to 20 µm; and/or the degree of graphitization of the first graphite and the second graphite each independently is 90% to 94%.
  18. Battery cell after one of the Claims 1 until 17 , wherein the coating quantity per unit area of the positive electrode active layer on a single side is 0.3 g/1540.25 mm² to 0.45 g/1540.25 mm² ; and/or the coating quantity per unit area of the negative electrode active layer on a single side is 0.13 g/1540.25 mm² to 0.22 g/1540.25 mm² .
  19. Battery cell after one of the Claims 1 until 18 , wherein the density of the positive electrode active layer is 2.3 g/cm 3 to 2.65 g/cm 3 ; and/or the density of the negative electrode active layer is 1.3 g/cm 3 to 1.52 g/cm 3 .
  20. Battery cell after one of the Claims 1 until 19 , wherein the positive electrode sheet comprises a carbon primer layer, the thickness of which is 0.5 µm to 3 µm.

Description

Related registration The present application claims priority over the Chinese patent application with application number 2025108313229 and the title “Battery cell, battery device and power-consuming device”, which was submitted on June 20, 2025, the full contents of which are hereby incorporated by reference. Technical field The present application relates to the technical field of secondary batteries, in particular a battery cell, a battery device and a power-consuming device. State of the art The cell of a stacked battery consists of alternating stacks of positive and negative electrode sheets. Compared to a wound battery, the stacked battery can achieve a higher energy density. This is because: (1) the cell of the stacked battery has no corners, thus utilizing more space within the battery; (2) due to the current winding process, the unfolded length of a wound battery is typically less than 300 mm, while the cell length of a stacked battery is not subject to this limitation. In comparison to the wound battery, however, the stacked battery has a less restrictive effect on the materials, which means that the active material layer and the separator can easily have poor contact, especially in the case where lithium iron phosphate is used as the positive electrode active material, the problem of electrode sheet misalignment occurs very easily, thus reducing the cycle performance of the stacked battery. Disclosure of the invention Based on this, the present application provides a battery cell, a battery device and a power-consuming device with good cycle performance. A first aspect of the present application provides a battery cell comprising a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte solution, wherein the positive electrode sheet, the separator, and the negative electrode sheet are arranged in alternating stacks; wherein the positive electrode sheet comprises a positive electrode current collector and a positive electrode active layer arranged on at least one side of the positive electrode current collector; wherein the negative electrode sheet comprises a negative electrode current collector and a negative electrode active layer arranged on at least one side of the negative electrode current collector, the positive electrode active layer containing primary particles of lithium iron phosphate; wherein the separator comprises a base film and a bonding layer, the bonding layer being a porous continuous structure, the bonding layer being arranged on at least one side of the base film facing the positive electrode active layer; wherein the electrolyte solution comprises a first solvent, wherein the first solvent comprises one or more of dimethyl carbonate and linear carboxylic acid ester, wherein a structural formula of the linear carboxylic acid ester is R 1 -COO-R 2 , wherein R 1 and R 2 each independently comprise a C1 to C5 alkyl group or a halogenated C1 to C5 alkyl group. As mentioned above, in the present application, where primary lithium iron phosphate particles are used as the positive electrode active material and a stacked cell is employed, the energy density and cycle life of the battery are improved, while simultaneously using a separator comprising a bonding layer with a porous continuous structure. The presence of the bonding layer can exert a strong bonding effect, ensuring a close connection between the separator and the positive electrode active layer containing the primary lithium iron phosphate particles. This allows the bonding layer to withstand the voltage changes generated by the primary lithium iron phosphate particles, thereby increasing the bonding stability between the positive electrode active layer and the separator, establishing good contact between them, and thus reducing the occurrence of electrode sheet misalignment and effectively improving the cycle life of the stacked battery. At the same time, the introduction of the bonding layer reduces the ion transport capacity of the separator, which is why a suitable Solvents are required to effectively increase the wettability of the electrolyte solution against the introduced separator, reduce the internal resistance of the battery, increase the ion transport performance, and thus comprehensively improve the cycle performance of the battery cell. In some embodiments, the thickness of the bonding layer on a single side is 0.5 µm to 2.5 µm, and optionally 1 µm to 2.5 µm. By appropriately controlling the thickness of the bonding layer, the stresses on the primary lithium iron phosphate particles can be better counteracted, increasing the stability of the battery structure. Furthermore, a higher energy density and lower internal resistance of the battery can be achieved, thereby comprehensively improving cycle performance. In some embodiments, the separator porosity ranges from 40% to 60%. By appropriately controlling the separator porosity, improved bonding capacity and increased battery stru