SECONDARY BATTERY AND RELEVANT BATTERY MODULE, BATTERY PACK AND APPARATUS

1 . A secondary battery, comprising: a positive electrode plate, a negative electrode plate, a separator disposed between the positive electrode plate and the negative electrode plate, and an electrolyte solution, the negative electrode plate including a negative electrode current collector and a negative electrode active material layer provided on at least one side of the negative electrode current collector, and the electrolyte solution including an organic solvent and a lithium salt, wherein

the negative electrode active material comprises a core structure and a polymer network coating layer coated on at least a part of the surface of the core structure, the core structure comprises SiO x (0<x<2), the polymer network coating layer accounts for at least 0.5 mass % and at most 10 mass % of the total mass of the negative electrode active material, and the network coating layer is derived from a polymer having one or more functional groups selected from a group consisting of cyano group, amide group, imide group, sulfonyl group, carboxyl group and sulfonyl group; and

the lithium salt comprises a primary lithium salt represented by Formula I:

in which Formula I, R 1 and R 2 each independently represent a fluorine atom, a fluoroalkyl group having 1-20 carbon atoms, or a fluoroalkoxy group having 1-20 carbon atoms, and n is an integer of 1, 2 or 3.

2 . The secondary battery according to claim 1 , wherein the polymer is selected from at least one of polyimide, polyacrylic acid, polyacrylamide and polyacrylonitrile.

3 . The secondary battery according to claim 1 , wherein the polymer network coating layer is present in an amount of 1 mass % to 5 mass % relative to the total mass of the negative electrode active material.

4 . The secondary battery according to claim 1 , wherein the primary lithium salt is selected from one or more of lithium bis(fluorosulfonyl)imide, lithium fluorosulfonyl(trifluoromethylsulfonyl) imide, lithium bis(trifluoromethylsulfonyl)imide, lithium methylsulfonyl(trifluoromethylsulfonyl) imide, lithium trifluoromethanesulfonyl(pentafluoroethyl sulfonyl) imide, lithium bis (pentafluoroethylsulfonyl)imide, LiN(SO 2 OCH 2 CF 3 ) 2 , LiN(SO 2 OCH 2 CF 2 CF 3 ) 2 , LiN(SO 2 OCH 2 CF 2 CF 2 H) 2 , LiN[(SO 2 OCH(CF 3 ) 2 ], FSO 2 N − (Li + )SO 2 N − (Li + )SO 2 F, FSO 2 N − (Li + )SO 2 N − (Li + )SO 2 N − (Li + )SO 2 F, FSO 2 N − (Li + )SO 2 N − (Li + )SO 2 CF 3 , CF 3 SO 2 N − (Li + )SO 2 N − (Li + )SO 2 CF 3 , and FSO 2 N − (Li + )SO 2 N − (Li + )SO 2 N − (Li + )SO 2 CF 3 , and optionally selected from one or more of lithium bis(fluorosulfonyl)imide, lithium fluorosulfonyl(trifluoromethylsulfonyl) imide, lithium bis(trifluoromethylsulfonyl)imide, FSO 2 N − (Li + )SO 2 N − (Li + )SO 2 F, FSO 2 N − (Li + )SO 2 N − (Li + )SO 2 N − (Li + )SO 2 F, FSO 2 N − (Li + )SO 2 N − (Li + )SO 2 CF 3 , CF 3 SO 2 N − (Li + )SO 2 N − (Li + )SO 2 CF 3 , and FSO 2 N − (Li + )SO 2 N − (Li + )SO 2 N − (Li + )SO 2 CF 3 .

5 . The secondary battery according to claim 1 , wherein the mass percentage concentration of the primary lithium salt in the electrolyte solution is in the range of 5% to 25%, and optionally in the range of 10% to 20%.

6 . The secondary battery according to claim 1 , wherein the lithium salt also comprises a secondary lithium salt, which is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium trifluoromethylsulfonate, lithium hexafluoroarsenate, lithium bisoxalate borate and lithium perchlorate, optionally selected from one or two of lithium hexafluorophosphate and lithium tetrafluoroborate, and more optionally, selected from lithium hexafluorophosphate.

7 . The secondary battery according to claim 1 , wherein the mass percentage concentration of the secondary lithium salt in the electrolyte solution is in the range of 0.1% to 10%, and optionally in the range of 3% to 5%.

8 . The secondary battery according to claim 1 , wherein the electrolyte solution also comprises an additive selected from one or more of ethylene sulfate (DTD), lithium difluorophosphate (LiPO 2 F 2 ), lithium difluoroxalate borate (LiODFB), maleic anhydride, sulfur dioxide (SO 2 ) and tris(trimethylsilane) phosphate (TMSP).

9 . The secondary battery according to claim 1 , wherein the mass percentage concentration of the additive in the electrolyte solution is in the range of 0% to 5%, optionally in the range of 0.1 to 3%, and more optionally in the range of 0.2% to 2%.

10 . The secondary battery according to claim 1 , wherein the organic solvent is selected from one or more of propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, vinylene carbonate, fluoroethylene carbonate, methyl formate, ethyl acetate, ethyl propionate, propyl propionate, methyl butyrate, methyl acrylate, ethylene sulfite, propylene sulfite, dimethyl sulfite, diethyl sulfite, 1,3-propanesulfonic acid lactone, vinyl sulfate, anhydride, N-methylpyrrolidone, N-methylformamide, N-methylacetamide, acetonitrile, N, N-dimethylformamide, sulfolane, dimethyl sulfoxide, methyl sulfide, γ-butyrolactone, tetrahydrofuran, fluorine-containing cyclic organic ester, sulfur-containing cyclic organic ester and unsaturated-bond-containing cyclic organic ester, and optionally, the mass percentage of the organic solvent in the electrolyte solution is from 65% to 85%.

11 . The secondary battery according to claim 1 , wherein the battery has a 4C rate of 40% or higher and a capacity retention rate of 70% or higher.

12 . A battery module comprising the secondary battery as claimed in claim 1 .

13 . An apparatus comprising the secondary battery as claimed in claim 1 , wherein the secondary battery is used as a power source or energy storage unit of the apparatus; optionally, the apparatus comprising electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, electric ships, or energy storage systems.