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CN-122025738-A - Battery cell, battery and electricity utilization device

CN122025738ACN 122025738 ACN122025738 ACN 122025738ACN-122025738-A

Abstract

The application provides a battery cell, a battery and an electricity utilization device, wherein the battery cell comprises an electrode assembly, the electrode assembly comprises an electrode pole piece and a separation membrane, the electrode pole piece comprises a current collector and a membrane layer which is arranged on at least one surface of the current collector and contains active substances and imbibition polymers, v/lambda is more than or equal to 1.2, v represents imbibition rate of the membrane layer in mg/s, lambda represents porosity of the membrane layer, the separation membrane comprises a liquid-retaining polymer, the separation membrane meets (M 2 -M)/(m 1 -M) more than or equal to 25%, M represents mass of the separation membrane which does not absorb electrolyte, the unit is g, M 1 represents mass of the separation membrane which is weighed under the environmental pressure after being soaked in the electrolyte for 2h, the unit is g, and M 2 represents mass of the separation membrane which is weighed under the environmental pressure for 10000N after being soaked in the electrolyte for 2 h.

Inventors

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

Assignees

  • 宁德时代新能源科技股份有限公司

Dates

Publication Date
20260512
Application Date
20230417

Claims (20)

  1. 1. A battery cell comprising an electrode assembly comprising an electrode sheet and a separator; the electrode plate comprises a current collector and a film layer which is arranged on at least one surface of the current collector and contains active substances and imbibition polymers, wherein v/lambda is more than or equal to 1.2, v represents imbibition rate of the film layer, and unit mg/s; λ represents the porosity of the film layer; The barrier film comprises a liquid retaining polymer, and the barrier film satisfies the following conditions: ; m represents the mass of the electrolyte which is not absorbed by the isolating film, and the unit is g; m 1 represents the mass of the isolating membrane weighed under the environment pressure after being immersed in the electrolyte for 2 hours, and the unit is g; m 2 represents the mass of the isolating membrane weighed under 10000N pressure in the ambient pressure after being immersed in the electrolyte for 2h, and the unit is g.
  2. 2. The battery cell according to claim 1, wherein the active material comprises a positive electrode active material, and the electrode tab satisfies 1.2 v/λ 4.50.
  3. 3. The battery cell according to claim 1 or 2, wherein the active material comprises a negative electrode active material, The electrode plate satisfies that v/lambda is more than or equal to 3 and less than 50.00.
  4. 4. The battery cell according to any one of claims 1 to 3, wherein the separator satisfies: ; Alternatively, the process may be carried out in a single-stage, Alternatively, the process may be carried out in a single-stage, 。
  5. 5. The battery cell according to any one of claims 1 to 4, wherein the separator satisfies: Alternatively, the process may be carried out in a single-stage,
  6. 6. The battery cell according to any one of claims 1 to 5, wherein the separator satisfies: Alternatively, the process may be carried out in a single-stage,
  7. 7. The battery cell of any one of claims 1-6, wherein the separator further comprises a liquid absorbing polymer; Alternatively, the process may be carried out in a single-stage, The liquid-absorbing polymer in the electrode sheet has a mass per unit volume of A1, The liquid absorbent polymer in the separator has a mass per unit volume of A2, A1/A2 is more than or equal to 1.0 and less than or equal to 1.6, alternatively, A1/A2 is more than or equal to 1.2 and less than or equal to 1.5.
  8. 8. The battery cell of any one of claims 1 to 7, wherein the electrode sheet further comprises a liquid-retaining polymer; Alternatively, the process may be carried out in a single-stage, The unit volume mass of the liquid-retaining polymer in the electrode pole piece is B1, The liquid-retaining polymer in the isolating film has a mass per unit volume of B2, B1/B2 is more than or equal to 0.4 and less than or equal to 0.9, alternatively, B1/B2 is more than or equal to 0.5 and less than or equal to 0.8.
  9. 9. The battery cell according to any one of claims 1 to 8, wherein, The liquid-absorbing polymer in the electrode plate has a unit volume mass of C1, and the liquid-retaining polymer in the isolating film has a unit volume mass of C2, wherein C1/C2 is more than or equal to 0.1 and less than or equal to 5.
  10. 10. The battery cell according to any one of claims 1 to 9, wherein, The liquid absorbent polymer includes at least one of an ether polymer, an ester polymer, a fluoropolymer, and an aldehyde ketone polymer; optionally, the liquid absorbent polymer comprises at least one of an ether polymer and an ester polymer; optionally, the liquid absorbent polymer comprises at least one of a fluoropolymer and an aldehyde ketone polymer.
  11. 11. The battery cell according to any one of claims 1 to 10, wherein, The liquid-retaining polymer comprises at least one of an ether polymer, an ester polymer, a fluoropolymer, and an aldehyde ketone polymer; Optionally, the liquid-retaining polymer comprises at least one of an ether polymer and an ester polymer; optionally, the liquid-retaining polymer comprises at least one of a fluoropolymer and an aldehyde ketone polymer.
  12. 12. The battery cell according to claim 10 or 11, wherein, The ether polymer is made into a sheet structure, the sheet structure is subjected to dynamic frequency scanning test at (T m2 +20) DEGC to obtain an elastic modulus G '-energy dissipation modulus G' curve, the slope of the elastic modulus G '-energy dissipation modulus G' curve is K 1 ,1＜K 1 ＜∞,T m2 ℃ and represents the melting temperature of the ether polymer, the melting temperature is less than or equal to 1<K 1 and less than or equal to 100, the melting temperature is less than or equal to 1<K 1 and less than or equal to 10, and the melting temperature is less than or equal to 1<K 1 and less than or equal to 2; Alternatively, the process may be carried out in a single-stage, The ether polymer includes at least one of a structural unit represented by the formula (BI) and a structural unit represented by the formula (BII), Formula (BI); In formula (BI), n is selected from positive integers from 1500 to 25000; 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; Formula (BII); In formula (BII), n is selected from positive integers from 1500 to 25000; R 24 to R 27 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 24 to R 27 comprises a substituted or unsubstituted C1-C3 alkoxy group or an ether group.
  13. 13. The battery cell according to any one of claims 10 to 12, wherein, The ester polymer is made into a sheet structure, the sheet structure is subjected to dynamic frequency scanning test at (T m3 +20) DEGC to obtain an elastic modulus G '-energy consumption modulus G' curve, the slope of the elastic modulus G '-energy consumption modulus G' curve is K 2 ,1＜K 2 ＜∞,T m3 ℃ and represents the melting temperature of the ester polymer, alternatively 1<K 2 is less than or equal to 100, further alternatively 1<K 2 is less than or equal to 10, further alternatively 1<K 2 is less than or equal to 2; Alternatively, the process may be carried out in a single-stage, The ester polymer comprises at least one of a structural unit represented by the formula (CI) and a structural unit represented by the formula (CII), Formula (CI); In the formula (CI), n is selected from positive integers of 1000 to 15000; 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; formula (CII); In the formula (CII), n is selected from positive integers of 1000 to 15000; 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.
  14. 14. The battery cell according to any one of claims 10 to 13, wherein, The crystallinity of the fluoropolymer measured by a differential scanning calorimetry method is Xc 1 ,0＜Xc 1 -30%, alternatively Xc 1 -25%; The melting temperature of the fluoropolymer is T m1 , the unit is the temperature of which is 0<T m1 to be less than or equal to 140, and optionally, T m1 to be more than or equal to 50 to be less than or equal to 135; Further alternatively, the fluoropolymer has a glass transition temperature of T g1 in units of °C, -150 ≡T g1 ≡60, and optionally, -80 ≡T g1 ≡35; still further alternatively, the fluoropolymer includes at least one of a structural unit represented by the formula (AI) to a structural unit 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; formula (AIII); In formula (AIII), R 15 comprises a single bond, a substituted or unsubstituted C1-C3 alkyl group, p is a positive integer from 1 to 3, and n is a positive integer from 1000 to 30000.
  15. 15. The battery cell according to any one of claims 10 to 14, wherein, The aldehyde ketone polymer is made into a sheet structure, the sheet structure is subjected to dynamic frequency scanning test at (T m3 +20) DEGC to obtain an elastic modulus G '-energy consumption modulus G' curve, the slope of the elastic modulus G '-energy consumption modulus G' curve is K 3 ,0.8≤K 3 ＜∞,T m3 ℃ and represents the melting temperature of the aldehyde ketone polymer, optionally, K 3 is more than or equal to 0.8 and less than or equal to 100, further optionally, K 3 is more than or equal to 0.8 and less than or equal to 10, and further optionally, K 3 is more than or equal to 0.8 and less than or equal to 2; Alternatively, the process may be carried out in a single-stage, The aldehyde ketone polymer includes at least one of a structural unit represented by formula (DI) and a structural unit represented by formula (DII), Formula (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; Formula (DII); In the formula (DII), R 43 to R 46 each independently comprises 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 of 0to 5, and at least one of R and s is selected from positive integers.
  16. 16. The battery cell of any one of claims 1 to 15, wherein the separator comprises a porous substrate, the liquid-retaining polymer being distributed in pores of the porous substrate.
  17. 17. The battery cell of any one of claims 1-16, wherein the separator comprises a porous substrate and a polymer layer disposed on at least one surface of the porous substrate, the polymer layer comprising the liquid-retaining polymer.
  18. 18. The battery cell of any one of claims 1 to 17, wherein the liquid-retaining polymer has a coating grammage of 0.5mg/1540.25mm 2 to 5mg/1540.25mm 2 .
  19. 19. The battery cell of any one of claims 1 to 18, wherein the electrode sheet is a positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer disposed on the positive electrode current collector, the positive electrode film layer comprising a positive electrode active material and a liquid absorbing polymer, the positive electrode active material comprising at least one of a lithium-containing phosphate compound, a lithium-containing transition metal oxide, a sodium-containing phosphate compound, and a sodium-containing transition metal oxide; Alternatively, the mass percentage of the liquid-absorbing polymer is 0.1% to 1.5% based on the mass of the positive electrode active material layer; Optionally, the positive electrode film layer includes a polymer layer containing a liquid-absorbing polymer and a positive electrode active material layer containing a positive electrode active material, where the positive electrode active material layer is disposed on at least one surface of the positive electrode current collector, and the polymer layer is disposed on a surface of the positive electrode active material layer facing away from the positive electrode current collector; Optionally, the positive electrode active materials are multiple, pores are formed between two adjacent positive electrode active materials, and the liquid-absorbing polymer is distributed in the pores.
  20. 20. The battery cell according to any one of claims 1 to 19, wherein, The electrode plate is a negative electrode plate, the negative electrode plate comprises a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, the negative electrode film layer comprises a negative electrode active substance and a liquid absorption polymer, and the negative electrode active substance comprises at least one of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials and lithium titanate; alternatively, the mass percentage of the liquid-absorbing polymer is 0.2% to 5.0% based on the mass of the anode active material layer; Optionally, the negative electrode film layer includes a polymer layer containing a liquid-absorbing polymer and a negative electrode active material layer containing a negative electrode active material, where the negative electrode active material layer is disposed on at least one surface of the negative electrode current collector, and the polymer layer is disposed on a surface of the negative electrode active material layer facing away from the negative electrode current collector; optionally, the plurality of negative electrode active materials are arranged, pores are arranged between two adjacent negative electrode active materials, and the liquid-absorbing polymer is distributed in the pores.

Description

Battery cell, battery and electricity utilization device The application is based on the application number 202380060956.8, the application date 2023, 04 and 17, and the application number Ningde is a divisional application of the application named "battery cell, battery and power utilization device". Technical Field The application relates to the field of batteries, in particular to a battery monomer, a battery and an electric device. Background The battery cell has the characteristics of high capacity, long service life and the like, and is widely applied to electronic equipment 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 becomes wider, the requirements on the performance of the battery cells become more stringent. However, the current battery cells have poor cycle performance and still require further improvement. Disclosure of Invention The present application has been made in view of the above problems, and an object thereof is to provide a battery cell, a battery, and an electric device. The first aspect of the application provides a battery monomer, which comprises an electrode assembly, wherein the electrode assembly comprises an electrode pole piece and a separation membrane, the electrode pole piece comprises a current collector and a membrane layer which is arranged on at least one surface of the current collector and contains active substances and liquid-absorbing polymers, the electrode pole piece meets the conditions that v/lambda is more than or equal to 1.2, v represents the liquid-absorbing rate of the membrane layer and the unit mg/s, lambda represents the porosity of the membrane layer, and the separation membrane comprises a liquid-retaining polymer, wherein the separation membrane meets the following conditions: 。 The electrolyte is more uniformly and fully soaked in the electrode pole piece, the stability of the battery monomer in the circulating process is improved, the electrolyte retaining polymer is arranged in the isolating film of the battery monomer, the liquid retaining capacity of the isolating film is higher, the electrolyte is not easy to be extruded in the circulating charge and discharge process of the battery monomer, the liquid shortage condition in the circulating charge and discharge process is reduced, the polarization of the battery is reduced, and the circulating performance of the battery monomer is improved. In some embodiments, the active material comprises a positive electrode active material, and the electrode sheet satisfies 1.2≤v/λ≤4.50. When the electrode pole piece meets the range, the liquid absorption rate is higher, and the back absorption rate of the electrolyte can be improved, so that the cycle performance of the battery monomer is improved. In some embodiments, the active material comprises a negative electrode active material, and the electrode sheet satisfies 3≤v/lambda <50.00. When the electrode pole piece meets the range, the liquid absorption rate is higher, and the back absorption rate of the electrolyte can be improved, so that the cycle performance of the battery monomer is improved. In some embodiments, the separator film satisfies: ; Alternatively, the process may be carried out in a single-stage, Alternatively, the process may be carried out in a single-stage,。 Therefore, when the isolating film of the embodiment of the application meets the conditions, the liquid retaining capacity of the isolating film can be further improved, the liquid shortage condition in the cyclic charge and discharge process can be further reduced, the battery polarization is reduced, and the cyclic performance of the battery monomer is improved. In some embodiments, the separator film satisfies: Alternatively, the process may be carried out in a single-stage, Therefore, when the isolating film of the embodiment of the application meets the conditions, the liquid retaining capacity of the isolating film can be further improved, the liquid shortage condition in the cyclic charge and discharge process can be further reduced, the battery polarization is reduced, and the cyclic performance of the battery monomer is improved. In some embodiments, the separator film satisfies: Alternatively, the process may be carried out in a single-stage, Therefore, when the isolating film of the embodiment of the application meets the conditions, the liquid retaining capacity of the isolating film can be further improved, the liquid shortage condition in the cyclic charge and discharge process can be further reduced, the battery polarization is reduced, and the cyclic performance of the battery monomer is improved. In some embodiments, the separator further comprises a liquid absorbent polymer, optionally, the liquid absorbent polymer in the electrode sheet has a mass per unit volume