Secondary battery comprising positive electrode plate and non-aqueous electrolyte solution

1. A secondary battery, comprising a positive electrode plate and a non-aqueous electrolyte solution, wherein

the positive electrode plate comprises a positive electrode active material, the positive electrode active material comprises an inner core and a shell cladding the inner core, and

the inner core comprises Li 1+x Mn 1−y A y P 1−z R z O 4 , wherein x=−0.100-0.100, y=0.001-0.500, z=0.001-0.100, A is selected from one or more elements in a group consisting of Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb and Ge, and optionally one or more elements in a group consisting of Fe, Ti, V, Ni, Co and Mg, and R is selected from one or more elements in a group consisting of B, Si, N and S;

the shell comprises a first cladding layer cladding the inner core, and a second cladding layer cladding the first cladding layer, wherein

the first cladding layer comprises pyrophosphate MP 2 O 7 and phosphate XPO 4 , wherein M and X are each independently selected from one or more elements in a group consisting of Li, Fe, Ni, Mg, Co, Cu, Zn, Ti, Ag, Zr, Nb and Al,

and the second cladding layer comprises carbon;

the non-aqueous electrolyte solution comprises a first additive, and the first additive comprises one or more compounds in a group consisting of a compound shown in Formula 1, a compound shown in Formula 2 and a compound shown in Formula 3:

R 1 and R 2 each independently represent any one of F, C1-C6 fluoroalkyl, C1-C6 alkyl, C1-C6 alkoxy, C2-C6 alkenyl, C2-C6 alkynyl and C6-C10 aryl, and at least one of R1 and R2 represents any one of F or C1-C6 fluoroalkyl;

R 3 and R 4 each independently represent any one of F, C1-C6 fluoroalkyl, C1-C6 alkyl, C1-C6 alkoxy, C2-C6 alkenyl and C2-C6 alkynyl, and at least one of R 3 and R 4 represents any one of F or C1-C6 fluoroalkyl;

R 5 and R 6 each independently represent any one of F, C1-C6 fluoroalkyl, C1-C6 alkyl, C1-C6 alkoxy, C2-C6 alkenyl, C2-C6 alkynyl, carbonyl, O—, ═O, — − BF3 and —O—BF 3 ;

M in each chemical formula each independently represents one of alkali metals and alkaline-earth metals; and

n is 0, 1 or 2.

2. The secondary battery according to claim 1 , wherein

R 1 and R 2 each independently represent any one of F, C1-C3 fluoroalkyl, C1-C3 alkyl, C1-C3 alkoxy, C2-C3 alkenyl, C2-C3 alkynyl, phenyl, benzyl and methylphenyl, and at least one of R1 and R2 represents any one of F or C1-C3 fluoroalkyl; and/or

R 3 and R 4 each independently represent any one of F, C1-C3 fluoroalkyl, C1-C3 alkyl, C1-C3 alkoxy, C2-C3 alkenyl and C2-C3 alkynyl, and at least one of R 3 and R 4 represents any one of F and C1-C3 fluoroalkyl and/or

R 5 and R 6 each independently represent any one of F, C1-C3 fluoroalkyl, C1-C3 alkyl, C1-C3 alkoxy, C2-C6 alkenyl, C2-C6 alkynyl, carbonyl, O—, ═O, — − BF 3 and —O − BF 3 ; and/or

M in each chemical formula each independently represents one of Li, Na and K.

3. The secondary battery according to claim 1 , wherein the first additive comprises one or more of the following compounds:

4. The secondary battery according to claim 1 , wherein the first additive comprises any one or more of the following compounds:

5. The secondary battery according to claim 1 , wherein

the non-aqueous electrolyte solution further comprises a second additive, and the second additive comprises one or more of compounds in a group consisting of a cyclic carbonate compound containing unsaturated bonds, a halogen-substituted cyclic carbonate compound, a sulfate compound, a sulfite compound, a sultone compound, a disulfonic acid compound, a nitrile compound, an aromatic compound, an isocyanate compound, a phosphazene compound, a cyclic anhydride compound, a phosphite compound, a phosphate compound and a borate compound.

6. The secondary battery according to claim 5 , wherein based on a total weight of the non-aqueous electrolyte solution, a content of the first additive is W1 wt %, and W1 is 0.01 to 20, and;

the W1/W2 is defined as M, and M is 0.001 to 20.

7. The secondary battery according to claim 1 , wherein the non-aqueous electrolyte solution further comprises an organic solvent and an electrolyte salt,

the organic solvent comprises one or more of a cyclic carbonate compound, a chain carbonate compound and a carboxylate compound, and further comprises one or more components in a group consisting of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, ethylene carbonate, propylene carbonate, butene carbonate, gamma-butyrolactone, methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, butyl propionate and tetrahydrofuran.

8. The secondary battery according to claim 1 , wherein

based on the weight of the inner core, the cladding amount of the first cladding layer is C1 wt %, and C1 is greater than 0 and less than or equal to 7, and optionally 4 to 5.6; and/or

based on the weight of the inner core, the cladding amount of the second cladding layer is C2 wt %, and C2 is greater than 0 and less than or equal to 6, and optionally 3 to 5.

9. The secondary battery according to claim 4 , wherein

based on a weight of the inner core, the cladding amount of the first cladding layer is C1 wt %, and C1 is greater than 0 and less than or equal to 7; and/or

based on the weight of the inner core, the cladding amount of the second cladding layer is C2 wt %, and C2 is greater than 0 and less than or equal to 6;

wherein a relational expression W1/(C1+C2) between a content W1 of the first additive and the cladding amount C1 of the first cladding layer as well as the cladding amount C2 of the second cladding layer is C, and C is 0.001 to 2.

10. The secondary battery according to claim 1 , wherein

the weight ratio of pyrophosphate to phosphate in the first cladding layer is 1:3 to 3:1, and optionally 1:3 to 1:1.

11. The secondary battery according to claim 1 , wherein

the interplanar spacing of phosphate in the first cladding layer is 0.345 to 0.358 nm, and an included angle between crystal orientations (111) is 24.25° to 26.45°; and

an interplanar spacing of pyrophosphate in the first cladding layer is 0.293 to 0.326 nm, and an included angle between crystal orientations (111) is 26.41° to 32.57°.

12. The secondary battery according to claim 1 , wherein

in the inner core, a ratio of y to 1-y is 1:10 to 10:1; and/or

in the inner core, a ratio of z to 1-z is 1:9 to 1:999, and optionally 1:499 to 1:249.

13. The secondary battery according to claim 1 , wherein

a crystallinity of pyrophosphate and phosphate is each independently 10% to 100%, and optionally 50% to 100%.

14. The secondary battery according to claim 1 , wherein

A is selected from at least two of Fe, Ti, V, Ni, Co and Mg.

15. The secondary battery according to claim 1 , wherein

a Li/Mn antisite defect concentration of the positive electrode active material is 4% or less, and optionally 2% or less.

16. The secondary battery according to claim 1 , wherein

a lattice change rate of the positive electrode active material is 6% or less, and optionally 4% or less.

17. The secondary battery according to claim 1 , wherein

a surface oxygen valence state of a positive electrode active material is −1.88 or less, and optionally −1.98 to −1.88.

18. The secondary battery according to claim 1 , wherein

a compacted density of the positive electrode active material at 3 tons (T) is 2.0 g/cm 3 or more, and optionally 2.2 g/cm 3 or more.

19. A battery module, comprising a plurality of the secondary batteries according to claim 1 .

20. A battery pack, comprising a plurality of the battery modules according to claim 19 .