NON-AQUEOUS ELECTROLYTE AND SECONDARY BATTERY, BATTERY MODULE, BATTERY PACK AND ELECTRICAL DEVICE CONTAINING THE SAME

1 . A non-aqueous electrolyte comprising an electrolyte salt, a non-aqueous solvent, and a first additive, wherein the electrolyte salt comprises:

lithium bis(fluorosulfonyl)imide, wherein based on the total mass of the non-aqueous electrolyte, lithium bis(fluorosulfonyl)imide is present in a mass content of A1;

lithium tetrafluoroborate, wherein based on the total mass of the non-aqueous electrolyte, lithium tetrafluoroborate is present in a mass content of A2; and

lithium difluoro(oxalate)borate, wherein based on the total mass of the non-aqueous electrolyte, lithium difluoro(oxalate)borate is present in a mass content of A3;

wherein the first additive comprises fluoroethylene carbonate, and wherein based on the total mass of the non-aqueous electrolyte, fluoroethylene carbonate is present in a mass content of B1; and

wherein the non-aqueous electrolyte satisfies that: A1 is from 9% to 15%, A1/A2 is from 30 to 1500, A1/B1 is from 3.6 to 15 and A2/A3 is from 0.02 to 30.

2 . The non-aqueous electrolyte according to claim 1 , wherein A1/A2 is from 50 to 250, optionally, A1/A2 is from 50 to 150; and/or

A1/B1 is from 4 to 9, optionally, A1/B1 is from 4 to 7; and/or

A2/A3 is from 0.5 to 13.5, optionally, A2/A3 is from 1 to 10.

3 . The non-aqueous electrolyte according to claim 1 , wherein the non-aqueous electrolyte further satisfies that: (A2+A3)/B1 is from 0.008 to 0.8, optionally, (A2+A3)/B1 is from 0.026 to 0.2.

4 . The non-aqueous electrolyte according to claim 1 , wherein the non-aqueous electrolyte satisfies at least one of the following (1) to (4):

(1) A1 is from 10% to 15%, optionally from 10% to 13%;

(2) A2 is from 0.01% to 0.3%, optionally from 0.05% to 0.2%;

(3) A3 from 0.01% to 0.5% and optionally from 0.015% to 0.1%

(4) B1 is from 1.0% to 2.5%, optionally from 1.5% to 2.5%.

5 . The non-aqueous electrolyte according to claim 1 , wherein non-aqueous solvent comprises:

a first solvent comprising at least one of ethylene carbonate, propylene carbonate and butylene carbonate, wherein the first solvent is present in a mass content of C1 in the non-aqueous solvent, based on the total mass of the non-aqueous solvent;

a second solvent comprising at least one of methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate and ethyl propyl carbonate, wherein the second solvent is present in a mass content of C2 in the non-aqueous solvent, based on the total mass of the non-aqueous solvent; and

a third solvent comprising at least one of methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate and ethyl butyrate, wherein the third solvent is present in a mass content of C3 in the non-aqueous solvent, based on the total mass of the non-aqueous solvent;

wherein the non-aqueous solvent satisfies that: C1 is from 10% to 30%, C2 is from 50% to 90% and C3 is from 0% to 20%;

optionally, C1/(C2+C3) is from 0.1 to 0.45, more optionally from 0.2 to 0.3.

6 . The non-aqueous electrolyte according to claim 1 , wherein the non-aqueous electrolyte further comprises: a second additive comprising at least one of vinylene carbonate, ethylene sulfate, 1,3-propanesultone; wherein the second additive is present in a mass content of B2 in the non-aqueous electrolyte, based on the total mass of the non-aqueous electrolyte; and wherein B2 is from 0.05% to 2%, optionally from 0.5% to 2%.

7 . The non-aqueous electrolyte according to claim 6 , wherein (A1+B2)/C1 is from 0.4 to 1.3, optionally from 0.4 to 0.8.

8 . The non-aqueous electrolyte according to claim 1 , wherein the non-aqueous electrolyte further comprises: a third additive comprising at least one of sulfamic acid and a salt thereof, wherein the third additive is present in a mass content of B3 in the non-aqueous electrolyte, based on the total mass of the non-aqueous electrolyte; and wherein B3 is from 0.005% to 0.1%, optionally from 0.005% to 0.05%.

9 . A secondary battery comprising a positive electrode plate, a negative electrode plate and a non-aqueous electrolyte, wherein the non-aqueous electrolyte is a non-aqueous electrolyte according to claim 1 .

10 . The secondary battery according to claim 9 , wherein the non-aqueous electrolyte has a conductivity at room temperature of x mS/cm, the negative electrode plate has a thickness of L μm,

and the secondary battery satisfies: L≤120×√{square root over (x/8)}.

11 . The secondary battery according to claim 9 , wherein the positive electrode plate comprises a layered material with a molecular formula of Li a Ni b Co c Mn d Al e M f O g A h , in which M represents a cation doped at transition metal site, A represents an anion doped at oxygen site, 0.8≤a≤1.2, 0≤b≤1, 0≤c≤1, 0≤d≤1, 0≤e≤1, 0≤f≤0.2 0≤g≤2, 0≤h≤2, b+c+d+e+f=1, g+h=2.

12 . The secondary battery according to claim 11 , wherein Li a Ni b Co c Mn d Al e M f O g A h satisfies at least one of the following (1) to (8):

(1) M is selected from at least one of Si, Ti, Mo, V, Ge, Se, Zr, Nb, Ru, Pd, Sb, Ce, Te, and W;

(2) A is selected from at least one of F, N, P, and S; optionally, A is selected from F;

(3) 0<b<0.98 and, optionally, 0.50≤b<0.98;

(4) c=0;

(5) 0<c≤0.20 and, optionally, 0<c≤0.10;

(6) d=0 and 0<e<0.50, optionally, d=0 and 0<e≤0.10;

(7) e=0 and 0<d<0.50, optionally, e=0 and 0<d≤0.10;

(8) 0<d<0.50 and 0<e<0.50, optionally, 0<d≤0.30 and 0<e≤0.10.

13 . A battery module comprising the secondary battery according to claim 9 .

14 . A battery pack comprising one of the secondary battery according to claim 9 .

15 . An electrical device comprising at least one of the secondary battery according to claim 9 .