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CN-121983517-A - Lithium ion secondary battery, battery and power utilization device

CN121983517ACN 121983517 ACN121983517 ACN 121983517ACN-121983517-A

Abstract

The present application relates to a lithium ion secondary battery, a battery and an electric device. The lithium ion secondary battery comprises a positive electrode plate, wherein the positive electrode plate comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, the positive electrode film layer comprises a positive electrode active substance and a lyophile polymer, and the coating weight of the positive electrode film layer is more than or equal to 300mg/1540.25mm 2 .

Inventors

  • Peng Shuangjuan
  • LI BAIQING
  • PENG LIN
  • JIN HAIZU
  • ZHAO FENGGANG
  • WU KAI

Assignees

  • 宁德时代新能源科技股份有限公司

Dates

Publication Date
20260505
Application Date
20231103

Claims (15)

  1. 1. The lithium ion secondary battery comprises a positive electrode plate, wherein the positive electrode plate comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, the positive electrode film layer comprises a positive electrode active substance and a lyophile polymer, and the coating weight of the positive electrode film layer is more than or equal to 300mg/1540.25mm 2 ; Optionally, the coating weight of the positive electrode film layer is 300mg/1540.25mm 2 to 500mg/1540.25mm 2 .
  2. 2. The lithium ion secondary battery according to claim 1, wherein the positive electrode active material comprises a lithium-containing phosphate; optionally, the mass content of the lithium-containing phosphate is equal to or more than 90% based on the total mass of the positive electrode active material; Further alternatively, the coating weight of the positive electrode film layer is more than or equal to 400mg/1540.25mm 2 , and the coating weight of the positive electrode film layer is 400mg/1540.25mm 2 to 500mg/1540.25mm 2 .
  3. 3. The lithium ion secondary battery of claim 2, wherein the lithium-containing phosphate comprises at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium nickel phosphate, lithium cobalt phosphate, and their respective modifying compounds; Optionally, the lithium-containing phosphate comprises a compound with a molecular formula of L x A y Me a M b P 1-c X c Y z and a modified compound thereof, wherein X is more than or equal to 0.5 and less than or equal to 1.3, Y is more than or equal to 0 and less than or equal to 1.3, x+y is more than or equal to 0.9 and less than or equal to 1.3, a is more than or equal to 0.9 and less than or equal to 1.5, b is more than or equal to 0.9 and less than or equal to 0.5, a is more than or equal to 0 and less than or equal to c is less than or equal to 0.5, z is more than or equal to 3 and less than or equal to 5;L and comprises one or more of Li and Na, A comprises one or more of Na, K and Mg, me comprises one or more of Mn, fe, co, ni, M comprises one or more of B, mg, al, si, P, S, ca, sc, ti, V, cr, cu, zn, sr, Y, zr, nb, mo, cd, sn, sb, te, ba, ta, W, yb, la, ce, X comprises one or more of S, si, cl, B, C, N, and Y comprises one or more of O, F.
  4. 4. The lithium ion secondary battery according to claim 1, wherein the positive electrode active material comprises a lithium-containing transition metal oxide; Optionally, the mass content of the lithium-containing transition metal oxide is greater than or equal to 90% based on the total mass of the positive electrode active material; Further alternatively, the coating weight of the positive electrode film layer is more than or equal to 300mg/1540.25mm 2 , and is 300mg/1540.25mm 2 to 500mg/1540.25mm 2 .
  5. 5. The lithium ion secondary battery of claim 4, wherein the lithium transition metal oxide comprises at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds; Optionally, the lithium-containing transition metal oxide comprises a compound with a molecular formula of L x A y Ni a Co b Mn c M (1-a-b-c) Y z and a modified compound thereof, wherein x is more than or equal to 0.5 and less than or equal to 2.1,0 and less than or equal to Y is more than or equal to 2.1, x+y is more than or equal to 0.9 and less than or equal to 2.1, a is more than or equal to 0 and less than or equal to 1, b is more than or equal to 0 and less than or equal to 1, c is more than or equal to 0 and less than or equal to 1, a+b+c is less than or equal to 1, z is more than or equal to 1.8 and less than or equal to 3.5, L comprises one or more of Li and Na, A comprises one or more of Na, K and Mg, M comprises one or more of B, mg, al, si, S, ca, sc, ti, V, cr, fe, cu, zn, sr, Y, zr, nb, mo, cd, sn, sb, te, ba, ta, W, yb, la, ce, and Y comprises one or more of O, F.
  6. 6. The lithium ion secondary battery according to any one of claims 1 to 5, wherein, Based on the total mass of the positive electrode film layer, the mass content of the lyophile polymer is less than or equal to 5%; Optionally, the mass content of the lyophile polymer is 0.05% to 5%; further alternatively, the lyophile polymer has a mass content of 0.10% to 5%; further alternatively, the lyophile polymer has a mass content of 0.20% to 5%; Further alternatively, the lyophile polymer has a mass content of 0.20% to 1%.
  7. 7. The lithium ion secondary battery according to any one of claims 1 to 6, wherein, The positive electrode film layer is a single-layer film layer, or The positive electrode film layer comprises a plurality of sub-layers, and the coating weight of the sub-layers is gradually reduced in the direction of pointing to the positive electrode film layer from the positive electrode current collector; Optionally, the plurality of sub-layers include a first layer and a second layer, the first layer is disposed on the surface of the positive electrode current collector, the second layer is located on a side of the first layer facing away from the positive electrode current collector, and a coating weight of the first layer is greater than a coating weight of the second layer; Further alternatively, the mass content of the lyophile polymer in the first layer is greater than the mass content of the lyophile polymer in the second layer; further alternatively, the mass content of the lyophile polymer in each of the sublayers is >0%, and the mass content of the lyophile polymer is less than or equal to 5%, alternatively less than or equal to 1%, further alternatively less than or equal to 0.5%.
  8. 8. The lithium ion secondary battery of any one of claims 1 to 7, wherein the lyophile polymer comprises a fluoropolymer having a crystallinity of Xc 1 %,0＜Xc 1 -28, optionally 5-Xc 1 -20, as measured by differential scanning calorimetry; The melting temperature of the fluoropolymer is T m1 ℃,0＜T m1 -130, alternatively, T m1 -120; Further alternatively, the fluoropolymer has a glass transition temperature T g1 ℃,-30≤T g1 ≤40, alternatively, the process may be carried out in a single-stage, T g1 is more than or equal to 0 and less than or equal to 15; still further alternatively, the fluoropolymer includes at least one of a compound represented by the formula (AI) to a compound represented by the formula (AIII), A compound of the formula (AI), The formula (AII), In the formula (AI) and the formula (AII), R 11 、R 12 、R 13 and R 14 each independently include a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group, and at least one of R 11 、R 12 、R 13 and R 14 contains a fluorine atom; the compound of formula (AIII), In formula (AIII), R 15 comprises a single bond, substituted or unsubstituted C1-C3 alkyl; p is selected from positive integers of 1 to 3; n is a positive integer from 1000 to 30000.
  9. 9. The lithium ion secondary battery according to any one of claims 1 to 8, wherein the lyophile polymer comprises an ether polymer, the ether polymer being formed into a sheet-like structure, the sheet-like structure being subjected to dynamic frequency sweep test at (T m2 +20) °c to obtain a modulus of elasticity G '-energy dissipation modulus G "curve, a slope of the modulus of elasticity G' -energy dissipation modulus G" curve of K 1 ,1＜K 1 ＜∞,T m2 ℃ representing a melting temperature of the ether polymer, optionally 1<K 1 +.100, further optionally 1<K 1 +.10, further optionally 1<K 1 +.2; optionally, the glass transition temperature of the ether polymer is T g2 ℃,-20≤T g2 -35; further alternatively, the ether polymer includes at least one of a compound represented by formula (BI) and a compound represented by formula (BII), Formula (BI), In formula (BI), R 21 and R 22 each independently comprise a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group, R 23 comprises a substituted or unsubstituted C1-C5 alkylene group; The formula (BII), In the formula (BII), R 24 to R 27 each independently include 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 24 to R 27 contains a substituted or unsubstituted C1-C3 alkoxy group or an ether group; The degree of polymerization n of the ether polymer is selected from positive integers from 1500 to 25000.
  10. 10. The lithium ion secondary battery according to any one of claims 1 to 9, wherein the lyophile polymer comprises the ester polymer, the ester polymer is made into a sheet-like structure, the sheet-like structure is subjected to dynamic frequency sweep test at (T m3 +20) ° to obtain an elastic modulus G '-energy consumption modulus G "curve, a slope of the elastic modulus G' -energy consumption modulus G" curve being K 2 ,1＜K 2 ＜∞,T m3 ℃ representing a melting temperature of the ester polymer, optionally 1<K 2 +.100, further optionally 1<K 2 +.10, further optionally 1<K 2 +.2; optionally, the glass transition temperature of the ester polymer is T g3 ℃,-20≤T g3 -35; Further alternatively, the ester polymer includes at least one of a compound represented by formula (CI) to a compound represented by formula (CIII), (CI), In the formula (CI), R 31 、R 32 and R 33 each independently comprise a hydrogen atom or a substituted or unsubstituted C1-C8 alkyl group, R 34 comprises a substituted or unsubstituted C1-C8 alkyl group or a substituted or unsubstituted C1-C8 hydroxyalkyl group; The formula (CII), In formula (CII), R 35 comprises a substituted or unsubstituted C2-C6 methylene group, alternatively R 35 each independently comprises a substituted or unsubstituted C2-C4 methylene group; The formula (CIII), In formula (CIII), R 36 、R 37 and R 38 each independently comprise a hydrogen atom, or a substituted or unsubstituted C1-C8 alkyl group, R 39 comprises a substituted or unsubstituted C1-C8 alkyl group; Alternatively, R 36 、R 37 and R 38 each independently comprise a hydrogen atom, a substituted or unsubstituted C1-C4 alkyl group; The polymerization degree n of the ester polymer is selected from positive integers of 800 to 20000.
  11. 11. The lithium ion secondary battery according to any one of claims 1 to 10, wherein the lyophile polymer comprises an aldehyde-ketone polymer, the aldehyde-ketone polymer being formed into a sheet-like structure, the sheet-like structure being subjected to dynamic frequency sweep test at (T m4 +20) ° to obtain a graph of elastic modulus G '-energy dissipation modulus G ", the slope of the graph of elastic modulus G' -energy dissipation modulus G" being K 3 ,0.8≤K 3 ＜∞,T m4 ℃ representing the melting temperature of the aldehyde-ketone polymer, optionally 0.8 ∈k 3 ∈100, further optionally 0.8 ∈k 3 ∈10, further optionally 0.8 ∈k 3 ∈2; optionally, the aldehyde ketone polymer has a glass transition temperature T g4 ℃,-20≤T g4 < 35; Further alternatively, the aldehyde ketone polymer includes at least one of a compound represented by formula (DI) and a compound represented by formula (DII), The composition of the composition (DI), In the formula (DI), R 41 comprises a single bond, a substituted or unsubstituted C1-C6 methylene group, R 42 comprises a hydrogen atom, a substituted or unsubstituted C1-C6 alkyl group; The formula (DII), In the formula (DII), R 43 to R 46 each independently include a hydrogen atom, a hydroxyl group, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 hydroxyalkyl group, or a substituted or unsubstituted C1-C3 alkoxy group; r and s are each independently selected from integers from 0 to 5, and at least one of r and s is selected from positive integers; The polymerization degree n of the aldehyde ketone polymer is selected from positive integers of 500 to 15000.
  12. 12. The lithium ion secondary battery according to any one of claims 1 to 11, wherein the molecular weight of the lyophile polymer is 2.0 x 10 5 g/mol to 1.2 x 10 6 g/mol.
  13. 13. The lithium ion secondary battery according to any one of claims 1 to 12, wherein the lithium ion secondary battery comprises a negative electrode tab including a negative electrode current collector and a negative electrode film layer provided on at least one side of the negative electrode current collector, the negative electrode film layer including a negative electrode active material including at least one of natural graphite, artificial graphite, soft carbon, hard carbon, a silicon-based material, a tin-based material, and lithium titanate.
  14. 14. A battery comprising the lithium ion secondary battery according to any one of claims 1 to 13.
  15. 15. An electrical device comprising the battery of claim 14.

Description

Lithium ion secondary battery, battery and power utilization device The application is based on the application number 202311460987.0, the application date 2023, 11 and 03, and the application is a divisional application of the application named as 'positive pole piece, battery and electricity utilization device' of New energy science and technology Co., ltd in the Ningde era. Technical Field The present application relates to a lithium ion secondary battery, a battery and an electric device. Background The battery has characteristics of high capacity, long life, and the like, and thus is widely used in electronic devices such as mobile phones, notebook computers, battery cars, electric automobiles, electric airplanes, electric ships, electric toy automobiles, electric toy ships, electric toy airplanes, electric tools, and the like. As the battery application range increases, the requirements for battery performance become increasingly stringent. However, it is difficult to improve the cycle performance, the power performance and the energy density of the battery, and further improvement is required. 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. In a first aspect, an embodiment of the application provides a lithium ion secondary battery, the lithium ion secondary battery comprises a positive electrode plate, the positive electrode plate comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, the positive electrode film layer comprises a positive electrode active substance and a lyophile polymer, and the coating weight of the positive electrode film layer is more than or equal to 300mg/1540.25mm 2. Therefore, the coating weight of the positive electrode film layer is relatively high, and the energy density of the battery monomer is high in the embodiment of the application, but the coating thickness is thick due to the high coating weight, so that the polarization phenomenon at the positive electrode film layer is aggravated, and the path of positive electrode active materials of lithium ions which are inserted into or separated from the positive electrode film layer is long, the internal resistance is high, and the power performance and the cycle life are poor. In the embodiment of the application, the lyophile polymer is further added in the positive electrode film layer, so that the lyophile polymer and the electrolyte have higher affinity, the infiltration rate of the electrolyte to the positive electrode film layer can be improved, the polarization phenomenon and the interface side reaction of the positive electrode film layer can be improved, and the cycle life can be prolonged. The lyophile polymer is configured to coat the electrolyte on the surface of the positive electrode active material particles, so that effective liquid storage points are formed on the surface of the positive electrode active material particles, and the migration rate of lithium ions can be accelerated, so that the power performance of the battery cell is improved. Thus, embodiments of the present application can improve cycle performance, power performance, and energy density at the same time. In some embodiments, the coating weight of the positive electrode film layer is 300mg/1540.25mm 2 to 500mg/1540.25mm 2. In some embodiments, the positive electrode active material comprises lithium-containing phosphate, optionally, the mass content of lithium-containing phosphate is greater than or equal to 90% based on the total mass of the positive electrode active material, further optionally, the coating weight of the positive electrode film layer is greater than or equal to 400mg/1540.25mm 2, optionally, 400mg/1540.25mm 2 to 500mg/1540.25mm 2. The lithium-containing phosphate is used as a main material of the positive electrode active material, the coating weight of the positive electrode film layer is relatively high, the energy density of the battery monomer is high, and the cycle life and the power performance can be improved by matching the lithium-containing phosphate with the lithium-containing phosphate. In some embodiments, the lithium-containing phosphate comprises at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium nickel phosphate, lithium cobalt phosphate, and their respective modifying compounds. In some embodiments, lithium-containing phosphates include compounds of the formula L xAyMeaMbP1-cXcYz and modified compounds thereof, wherein 0.5≤x≤1.3, 0≤y≤1.3, and 0.9≤x+y≤1.3, 0.9≤a≤1.5, 0.9≤b≤0.5, 0.9≤a+b≤1.5, 0≤c≤0.5, 3≤z≤ 5;L includes one or more of Li, na, A includes one or more of Na, K, mg, me includes one or more of Mn, fe, co, ni, M includes one or more of B, mg, al, si, P, S, ca, sc, ti, V, cr, cu, zn, sr, Y, zr, nb, mo, cd, sn, sb, te