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CN-122025536-A - Lithium ion secondary battery, battery and power utilization device

CN122025536ACN 122025536 ACN122025536 ACN 122025536ACN-122025536-A

Abstract

The application provides a lithium ion secondary battery, a battery and an electric device. The lithium ion secondary battery comprises a pole piece, the pole piece comprises a current collector and an active material layer arranged on at least one surface of the current collector, the active material layer comprises an active material and an ether polymer, the active material layer is in accordance with formulas (1) to (3), the ether polymer is used as a component part of the active material layer, uniform high-infiltration points can be formed inside the active material layer, and the infiltration performance of the active material layer is uniformly improved, so that the overall liquid absorption speed of the active material layer is improved, and the cycle performance of the lithium ion secondary battery is improved. Equation (1) Formula (2) v/lambda >1.00 formula (3).

Inventors

  • Peng Shuangjuan
  • PENG LIN
  • LI BAIQING

Assignees

  • 宁德时代新能源科技股份有限公司

Dates

Publication Date
20260512
Application Date
20230217

Claims (14)

  1. 1. A lithium ion secondary battery comprising a pole piece comprising a current collector and an active material layer disposed on at least one surface of the current collector, the active material layer comprising an active material and an ether polymer, the active material layer satisfying: (1), (2), V/lambda >1.00 formula (3); in the formulas (1) to (3), Λ represents the porosity of the active material layer; P 1 represents the actual compacted density of the active material layer in g/cm 3 ; P 2 represents the true compacted density of the active substance in g/cm 3 ; v represents the imbibition rate of the active material layer in mg/s; d represents the diameter of the capillary of the active material layer in mm in a capillary test; h represents the liquid level in the capillary in mm; Represents the density of the electrolyte in the capillary test in g/cm 3 ; t represents the time in s for the electrolyte to be absorbed in the capillary.
  2. 2. The lithium ion secondary battery according to claim 1, wherein the active material comprises a positive electrode active material, Optionally, the positive electrode active material includes at least one of a layered structure positive electrode active material, an olivine-type phosphate active material, and a spinel structure positive electrode active material; Alternatively, the active material layer satisfies 1.00< v/lambda <4.00, alternatively 1.20. Ltoreq.v/lambda. Ltoreq.3.80, further alternatively 1.4. Ltoreq.v/lambda. Ltoreq.3.6.
  3. 3. The lithium ion secondary battery according to claim 1 or 2, wherein the active material comprises a positive electrode active material, The mass percentage content of the ether polymer is A% based on the mass of the active material layer; Wherein A is more than or equal to 0.1 and less than or equal to 1.5, alternatively, A is more than or equal to 0.5 and less than or equal to 1.5.
  4. 4. The lithium ion secondary battery according to claim 1, wherein the active material comprises a negative electrode active material, Optionally, the negative active material includes at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, and lithium titanate; Alternatively, the active material layer satisfies 3.00< v/lambda <50.00, alternatively 3.40. Ltoreq.v/lambda. Ltoreq.34.5, further alternatively 3.40. Ltoreq.v/lambda. Ltoreq.30.00.
  5. 5. The lithium ion secondary battery according to claim 1 or 4, wherein the active material comprises a negative electrode active material, The mass percentage content of the ether polymer is B% based on the mass of the active material layer; wherein B is more than or equal to 0.2 and less than or equal to 5.0, alternatively, B is more than or equal to 2.5 and less than or equal to 5.0.
  6. 6. The lithium ion secondary battery according to any one of claims 1 to 5, wherein, Forming the ether polymer into a sheet-like structure; The sheet structure is subjected to dynamic frequency scanning test at (T m +20) DEGC to obtain an elastic modulus G '-dissipative modulus G' curve, wherein the slope of the elastic modulus G '-dissipative modulus G' curve is K,1<K < +%, optionally 1<K is less than or equal to 100, further optionally 1<K is less than or equal to 10, and T m ℃ represents the melting temperature of the ether polymer.
  7. 7. The lithium ion secondary battery according to any one of claims 1 to 6, wherein, The glass transition temperature of the ether polymer is Tg, and the unit is that the temperature is minus 100 ℃ and minus 50, the Tg is minus 80 and minus 30, the Tg is minus 80 and minus 0.
  8. 8. The lithium ion secondary battery according to any one of claims 1 to 7, wherein the ether polymer comprises a structural unit represented by the formula (I), Formula (I); In the formula (I) of the present invention, R 1 and R 2 each independently comprise a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group or a substituted or unsubstituted C1-C3 alkoxy group, R 3 comprises a substituted or unsubstituted C1-C5 methylene group; Optionally, R 1 and R 2 each independently comprise a hydrogen atom, a substituted or unsubstituted C1-C2 alkyl group, and/or R 3 comprises a single bond, a substituted or unsubstituted C1-C4 methylene group.
  9. 9. The lithium ion secondary battery according to claim 8, wherein the ether polymer comprises at least one of a structural unit represented by formula (I-1) to a structural unit represented by formula (I-8), A compound of the formula (I-1), A compound of the formula (I-2), A compound of the formula (I-3), A compound of the formula (I-4), A compound of the formula (I-5), A compound of the formula (I-6), A compound of the formula (I-7), Formula (I-8).
  10. 10. The lithium ion secondary battery according to any one of claim 1 to 9, wherein the ether polymer comprises a structural unit represented by formula (II), Formula (II); In the formula (II) of the present invention, R 4 to R 7 each independently comprise a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 alkoxy group, or an ether group, and at least one of R 4 to R 7 comprises a substituted or unsubstituted C1-C3 alkoxy group or an ether group; Alternatively, R 4 to R 7 each independently include a hydrogen atom, a substituted or unsubstituted C1-C2 alkyl group, a substituted or unsubstituted C1-C2 alkoxy group, or an ether group, and at least one of R 4 to R 7 includes a substituted or unsubstituted C1-C2 alkoxy group, or an ether group.
  11. 11. The lithium ion secondary battery according to claim 10, wherein the ether polymer comprises at least one of a structural unit represented by the formula (II-1) to a structural unit represented by the formula (II-7), A compound of the formula (II-1), A compound of the formula (II-2), A compound of the formula (II-3), A compound of the formula (II-4), A compound of the formula (II-5), A compound of the formula (II-6), (II-7)。
  12. 12. The lithium ion secondary battery according to any one of claims 8 to 11, wherein, N is selected from a positive integer from 1500 to 25000, and/or The molecular weight of the ether polymer is 1.2X10 5 g/mol to 1.0X10 6 g/mol.
  13. 13. A battery comprising the lithium ion secondary battery according to claim 12.
  14. 14. An electrical device comprising the battery of claim 13.

Description

Lithium ion secondary battery, battery and power utilization device The application is based on the application number 20238056789. X, the application date is 2023, 02 and 17, and the application is a division application of Ningde times of New energy science and technology Co., ltd, the application name of which is 'pole piece and related lithium ion secondary battery, battery and electricity utilization device'. Technical Field The application relates to the field of batteries, in particular to a lithium ion secondary battery, a battery and an electric device. Background Lithium ion secondary batteries have characteristics of high capacity, long life, and the like, and thus are widely used in electronic devices such as mobile phones, notebook computers, battery cars, electric automobiles, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, electric tools, and the like. As the battery application range is becoming wider, the requirements for the performance of lithium ion secondary batteries are also becoming more stringent. In order to improve the safety performance of the lithium ion secondary battery, the performance of a pole piece in the lithium ion secondary battery is generally optimized and improved. However, the active material in the current pole piece has poor liquid absorption performance, so that the cycle performance of the lithium ion secondary battery is poor when the active material is applied to the lithium ion secondary battery. Disclosure of Invention The present application has been made in view of the above problems, and an object thereof is to provide a lithium ion secondary battery, a battery, and an electric device. A first aspect of the present application provides a lithium ion secondary battery comprising a pole piece including a current collector and an active material layer disposed on at least one surface of the current collector, the active material layer including an active material and an ether polymer, the active material layer satisfying: (1), (2), V/lambda >1.00 formula (3), In the formulas (1) to (3), Λ represents the porosity of the active material layer; P 1 represents the actual compacted density of the active material layer in g/cm 3; P 2 represents the true compacted density of the active substance in g/cm 3; v represents the liquid absorption rate of the active material layer, in mg/s, D represents the diameter of the capillary of the active material layer in mm in the capillary test; h represents the liquid level in the capillary, and the unit is mm; Represents the density of the electrolyte in the capillary test in g/cm 3; t represents the time in which the electrolyte is absorbed in the capillary, and is expressed in units of s. Therefore, the ether polymer is introduced in the preparation process of the active material layer, so that uniform high-infiltration points can be formed inside the active material layer, the infiltration performance of the active material layer is uniformly improved, the overall liquid absorption speed of the active material layer is improved, and the cycle performance of the lithium ion secondary battery adopting the pole piece is improved. In some embodiments, the active material includes a positive electrode active material, optionally, the positive electrode active material includes at least one of a layered structure positive electrode active material, an olivine-type phosphate active material, a spinel structure positive electrode active material. In some embodiments, the active material layer satisfies 1.00< v/lambda <4.00, alternatively 1.20. Ltoreq.v/lambda. Ltoreq.3.80, further alternatively 1.4. Ltoreq.v/lambda. Ltoreq.3.6. In some embodiments, the active material comprises a positive electrode active material, the mass percent of the ether polymer is A% based on the mass of the active material layer, wherein 0.1≤A≤1.5, alternatively 0.5≤A≤1.5. When the mass percentage of the ether polymer is within the above range, the liquid absorbing ability of the positive electrode active material layer can be significantly improved. In some embodiments, the active material includes a negative electrode active material, optionally including at least one of artificial graphite, natural graphite, soft carbon, hard carbon, a silicon-based material, a tin-based material, and lithium titanate. In some embodiments, the active material layer satisfies 3.00< v/lambda <50.00, alternatively 3.40. Ltoreq.v/lambda≤34.5, further alternatively 3.40. Ltoreq.v/lambda≤30.00. In some embodiments, the active material comprises a negative electrode active material, the mass percent of the ether polymer is B% based on the mass of the active material layer, wherein 0.2≤B≤5.0, optionally 2.5≤B≤5.0. When the mass percentage of the ether polymer is within the above range, the liquid absorbing ability of the anode active material layer can be significantly improved. In some embodiments, the ether polymer is formed