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CN-122025774-A - Gel electrolyte and secondary lithium ion semi-solid battery

CN122025774ACN 122025774 ACN122025774 ACN 122025774ACN-122025774-A

Abstract

The application belongs to the field of batteries, and particularly relates to a novel gel electrolyte and a secondary lithium ion semi-solid battery. The application provides an alkenyl sulfur-containing precursor, which can participate in film formation through a side chain sulfur-containing group after gelation, so that the interface stability is improved, and the gel polymer can be effectively contacted with a negative electrode interface. The cycle life, high-temperature gas production and safety performance of the high-energy density semi-solid gel battery can be improved by controlling the type and mass fraction of the sulfur-containing polymer precursor, the mass fraction of the crosslinked polymer precursor, the mass fraction of the sulfur-containing additive, the mass fraction of the lithium salt-type additive, the mass fraction of the silicon-based anode material in the anode active material and the compacted density of the anode active material layer in the gel electrolyte to satisfy specific relations.

Inventors

  • LI MINGLIANG
  • ZHU XINGBAO
  • ZHANG WENQIANG
  • LI XIAOLONG
  • ZHOU XUEFENG

Assignees

  • 合肥国轩高科动力能源有限公司

Dates

Publication Date
20260512
Application Date
20260113

Claims (10)

  1. 1. A secondary battery, characterized by comprising: The positive electrode plate is provided with a plurality of electrodes, A negative electrode sheet comprising a negative electrode active material comprising a silicon-based material, and The electrolyte comprises a gel polymer precursor and an electrolyte, wherein the gel polymer precursor comprises a sulfur-containing polymer precursor and a crosslinked polymer precursor, and the electrolyte comprises a sulfur-containing additive and a lithium salt type additive; The secondary battery satisfies F = F is more than or equal to 4.0 and less than or equal to 10.5; wherein alpha is the mass fraction of the sulfur-containing polymer precursor based on the total mass of the electrolyte; beta is the mass fraction of the crosslinked polymer precursor based on the total mass of the electrolyte; x is the mass fraction of sulfur-containing additives, based on the total mass of the electrolyte; y is the mass fraction of the lithium salt type additive, based on the total mass of the electrolyte; PD is the negative electrode active material layer solid density; w is the mass fraction of the silicon-based anode material in the anode active material, and the mass fraction is based on the total mass of the anode active material.
  2. 2. The secondary battery according to claim 1, wherein the sulfur-containing polymer precursor is at least any one of a1 to a 2: a1. A compound having the formula I or II: ; Wherein R 1 、R 2 、R 4 、R 5 is hydrogen, fluorine, substituted or unsubstituted alkyl with 1-12 carbon atoms, substituted or unsubstituted alkenyl, aryl, heteroaryl and alkoxy; R 3 、R 6 is a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alkenyl group, an aryl group, or a heteroaryl group; a2. 0.3 wt% ≤α≤2.0 wt%。
  3. 3. the secondary battery according to claim 1, wherein the sulfur-containing polymer precursor is at least any one of compounds having structural formulas I-1 to 7 and II-1 to 8: 。
  4. 4. the secondary battery according to claim 1, wherein the crosslinked polymer precursor is at least any one of b1 to b 2: b1. At least one selected from the group consisting of ethylene glycol diacrylate, ethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, ethoxylated trimethylolpropane triacrylate, tripropoxylated trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, bis (trimethylolpropane) tetraacrylate, polydipentaerythritol pentaacrylate, polydipentaerythritol hexaacrylate, allyl alkenyl sulfonate, and 1, 3-divinyl-1, 3-tetramethoxy disiloxane; b2.1.0 wt% ≤β≤3.0 wt%。
  5. 5. the secondary battery according to claim 1, wherein the sulfur-containing additive is at least any one of c1-c 2: c1. at least one selected from the group consisting of vinyl sulfate, 1, 3-propane sultone, 1, 4-butane sultone, methylene methane disulfonate, vinyl disulfate, pentaerythritol dicyclosulfate, mannitol carbonate sulfate, vinyl sulfite and propylene sulfite; c2. 0.5 wt%≤x≤3.0 wt%。
  6. 6. The secondary battery according to claim 1, wherein the lithium salt type additive is at least any one of d1 to d 2: d1. At least one selected from lithium bisoxalato borate, lithium difluorooxalato borate, lithium difluorophosphate, lithium difluorobisoxalato phosphate, lithium tetrafluorooxalato phosphate, lithium fluorosulfonate, lithium trifluoromethylsulfinate, lithium trifluoromethylsulfonate, lithium difluoromalonate borate and lithium difluoro (2, 2-difluoromalonate) borate; d2. 0.5 wt% ≤y≤2.5 wt%。
  7. 7. the secondary battery according to claim 1, wherein the compacted density PD of the anode active layer satisfies that PD is 1.50≤PD≤1.70.
  8. 8. The secondary battery according to claim 1, wherein the mass fraction w of the silicon-based anode material in the anode active material satisfies 10 wt% w≤30: 30 wt%.
  9. 9. The secondary battery according to claim 1, wherein at least any one of the following e1 to e 6: e1. the electrolyte solvent is selected from at least one of fluorocarbonate, non-fluorocarbonate and non-fluorocarboxylate; e2. the fluorocarbonate is at least one selected from fluoroethylene carbonate, 4-trifluoromethyl ethylene carbonate, (trifluoroethyl) methyl carbonate and di (trifluoroethyl) carbonate; e3. the non-fluorinated carbonate is at least one selected from ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl 2, 5-dioxaadipate and diethyl 2, 5-dioxaadipate; e4. The non-fluorinated carboxylic ester is at least one selected from ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate and ethyl butyrate; e5. The positive electrode sheet comprises a positive electrode active material, wherein the positive electrode active material comprises lithium nickel cobalt manganese oxide; e6. in the lithium nickel cobalt manganese oxide, the molar percentage content B of the nickel element is more than or equal to 70 percent based on the molar amount of metal elements except lithium.
  10. 10. An electric device comprising the secondary battery according to any one of claims 1 to 9.

Description

Gel electrolyte and secondary lithium ion semi-solid battery Technical Field The invention belongs to the field of batteries, and particularly relates to a novel gel electrolyte and a secondary lithium ion semi-solid battery. Background At present, a secondary lithium ion battery with high energy density, high safety and long service life has become a hot spot direction for the development of the current novel battery technology. In order to meet the requirements of high energy density and high safety performance, an all-solid-state battery is an effective solution thought, and the problems of electrolyte leakage, thermal runaway combustion and the like can be solved by using the solid-state electrolyte with high thermal stability and high chemical stability to completely replace the liquid electrolyte, but the problems of low conductivity, overlarge solid-solid interface contact impedance, solid-solid contact failure caused by overlarge stress deformation in the circulation process and the like exist. In order to effectively be compatible with the high power performance of the liquid lithium ion battery and the high safety performance of the all-solid-state battery, developing the high-energy-density semi-solid-state lithium ion gel battery has become a tracking hot spot of new energy enterprises. The semisolid lithium ion gel battery can ensure that liquid electrolyte is stably bound in a gel polymer network, so that the battery core system has no free electrolyte, is compatible with the existing manufacturing process of the liquid lithium ion battery, and has high mass production degree. The existing high-energy-density semi-solid lithium ion gel battery mainly uses a high-nickel ternary material, a high-content silicon/graphite negative electrode and a gel electrolyte, and has various problems such as insufficient power performance, short cycle life and the like. The method mainly comprises the following three aspects of 1) insufficient interface stability caused by insufficient formation of a formed film after gelation of electrolyte, 2) dynamic growth of an SEI film caused by overlarge volume expansion of a silicon anode material in a cyclic process, and aggravation of active lithium loss caused by incapability of effectively repairing the SEI film after gelation, 3) incapability of realizing effective contact between a gel polymer and an anode interface, worsening of contact internal resistance caused by large expansion and contraction of the silicon anode material in a cyclic charge and discharge process, increase of polarization, aggravation of reversible capacity loss and the like. Disclosure of Invention In one aspect, the present invention provides a secondary battery comprising: The positive electrode plate is provided with a plurality of electrodes, A negative electrode sheet comprising a negative electrode active material comprising a silicon-based material, and The electrolyte comprises a gel polymer precursor and an electrolyte, wherein the gel polymer precursor comprises a sulfur-containing polymer precursor and a crosslinked polymer precursor, and the electrolyte comprises a sulfur-containing additive and a lithium salt type additive; The secondary battery satisfies F = F is more than or equal to 4.0 and less than or equal to 10.5; wherein alpha is the mass fraction of the sulfur-containing polymer precursor based on the total mass of the electrolyte; beta is the mass fraction of the crosslinked polymer precursor based on the total mass of the electrolyte; x is the mass fraction of sulfur-containing additives, based on the total mass of the electrolyte; y is the mass fraction of the lithium salt type additive, based on the total mass of the electrolyte; PD is the negative electrode active material layer solid density; w is the mass fraction of the silicon-based anode material in the anode active material, and the mass fraction is based on the total mass of the anode active material. In some embodiments, the sulfur-containing polymer precursor is at least any one of a1-a 2: a1. A compound having the formula I or II: ; Wherein R 1、R2、R4、R5 is hydrogen, fluorine, substituted or unsubstituted alkyl with 1-12 carbon atoms, substituted or unsubstituted alkenyl, aryl, heteroaryl and alkoxy; R 3、R6 is a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alkenyl group, an aryl group, or a heteroaryl group; a2. 0.3 wt% ≤α≤2.0 wt%。 in some embodiments, the sulfur-containing polymer precursor is at least any one of the compounds having the structural formulas I-1 to 7 and II-1 to 8: 。 in some embodiments, the crosslinked polymer precursor is at least any one of b1-b 2: b1. At least one selected from the group consisting of ethylene glycol diacrylate, ethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol diacrylate, poly