Secondary battery, battery module, battery pack, and electrical apparatus
Provided are a secondary battery, a battery module, a battery pack, and an electrical apparatus. The secondary battery comprises a positive electrode plate and a non-aqueous electrolyte solution, where the positive electrode plate comprises a positive electrode active material having a core-shell structure and comprising an inner core and a shell cladding the inner core, where the inner core has a chemical formula of Li 1+x Mn 1−y A y P 1−z R z O 4 , a first cladding layer comprises crystalline pyrophosphates Li a MP 2 O 7 and/or M b (P 2 O 7 ) c , a second cladding layer comprises a crystalline phosphate XPO 4 , and a third cladding layer is carbon; and the non-aqueous electrolyte solution comprises a first additive comprising one or more compounds in the group consisting of a compound represented by formula 1, a compound represented by formula 2, and a compound represented by formula 3, thereby improving rate performance, cycling performance, and high-temperature stability of a lithium manganese phosphate secondary battery.
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 having a core -shell structure and comprising an inner core and a shell cladding the inner core, wherein
the inner core has a chemical formula of Li 1+x Mn 1−y AyP 1−z R z O 4 , wherein x is any value ranging from −0.100 to 0.100, y is any value ranging from 0.001 to 0.500, z is any value ranging from 0.001 to 0.100, the A is one or more elements selected from the group consisting of Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb, and Ge; R is one or more elements selected from the group consisting of B, Si, N, and S;
the shell comprises a first cladding layer cladding the inner core, a second cladding layer cladding the first cladding layer, and a third cladding layer cladding the second cladding layer, wherein
the first cladding layer comprises crystalline pyrophosphates LiaMP 2 O 7 and/or M b (P 2 O 7 ) c , wherein 0≤a≤2, 1≤b≤4, and 1≤c≤6, values of the a, b, and c satisfy a condition of: keeping the crystalline pyrophosphate Li a MP 2 O 7 or M b (P 2 O 7 ) c electroneutral, and M in the crystalline pyrophosphates Li a MP 2 O 7 and M b (P 2 O 7 ) c is each independently one or more elements selected from the group consisting of Fe, Ni, Mg, Co, Cu, Zn, Ti, Ag, Zr, Nb, and Al,
the second cladding layer comprises a crystalline phosphate XPO 4 , wherein the X is one or more elements selected from the group consisting of Li, Fe, Ni, Mg, Co, Cu, Zn, Ti, Ag, Zr, Nb, and Al, and
the third cladding layer is carbon; and
the non-aqueous electrolyte solution comprises a first additive comprising one or more compounds in the group consisting of a compound represented by formula 1, a compound represented by formula 2, and a compound represented by formula 3,
wherein 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, or C6-C10 aryl, and at least one of R 1 or R 2 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, or C2-C6 alkynyl, and at least one of R 3 or 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, —BF 3 − , or —OBF 3 − ,
M in each chemical formula each independently represents one or more of an alkali metal or an alkaline earth metal, 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, or methylphenyl, at least one of R 1 or R 2 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, or C2-C3 alkynyl, at least one of R 3 or R 4 represents any one of F or 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 − , or —OBF 3 − ; and/or
M in each chemical formula each independently represents one of Li, Na, or K.
3. The secondary battery according to claim 1 , wherein
the first additive comprises one or more compounds of:
4. The secondary battery according to claim 1 , wherein
the first additive comprises any one or more compounds of:
5. The secondary battery according to claim 1 , wherein
the non-aqueous electrolyte solution further comprises a second additive comprising one or more compounds in the group consisting of an unsaturated bond-containing cyclic carbonate compound, 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, or 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 %, wherein W1 is from 0.005 to 20,
and/or a content of the second additive is W2 wt %, wherein W2 is from 0.001 to 20.
7. The secondary battery according to claim 5 , wherein
based on a weight of the inner core, a cladding amount of the first cladding layer is C1 wt %, wherein C1 is greater than 0 and less than or equal to 6; and/or
based on the weight of the inner core, a cladding amount of the second cladding layer is C2 wt %, wherein C2 is greater than 0 and less than or equal to 6; and/or
based on the weight of the inner core, a cladding amount of the third cladding layer is C3 wt %, wherein C3 is greater than 0 and less than or equal to 6; and
based on a total weight of the non-aqueous electrolyte solution, a content of the first additive is W1 wt %, a content of the second additive is W2 wt %: and
a ratio (W1+W2)/(C1+C2+C3) is defined as Q, wherein Q is from 0.001 to 2.
8. The secondary battery according to claim 1 , wherein
the non-aqueous electrolyte solution further comprises an organic solvent and an electrolyte salt.
9. The secondary battery according to claim 1 , wherein
based on a weight of the inner core, a cladding amount of the first cladding layer is C1 wt %, wherein C1 is greater than 0 and less than or equal to 6; and/or
based on the weight of the inner core, a cladding amount of the second cladding layer is C2 wt %, wherein C2 is greater than 0 and less than or equal to 6; and/or
based on the weight of the inner core, a cladding amount of the third cladding layer is C3 wt %, wherein C3 is greater than 0 and less than or equal to 6.
10. The secondary battery according to claim 1 , wherein
an interplanar spacing of the crystalline pyrophosphate in the first cladding layer ranges from 0.293 to 0.470 nm, and an angle in a crystallographic direction (111) ranges from 18.00° to 32.00°; and
an interplanar spacing of the crystalline pyrophosphate in the second cladding layer ranges from 0.244 to 0.425 nm, and an angle in the crystallographic direction (111) ranges from 20.00° to 37.00°.
11. The secondary battery according to claim 1 , wherein
in the inner core, a ratio of y to 1−y is from 1:10 to 1:1; and/or
in the inner core, a ratio of z to 1−z is from 1:9 to 1:999.
12. The secondary battery according to claim 1 , wherein
carbon of the third cladding layer is a mixture of SP2 hybridized carbon and SP3 hybridized carbon.
13. The secondary battery according to claim 1 , wherein
a thickness of the first cladding layer is from 1 to 10 nm; and/or
a thickness of the second cladding layer is from 2 to 15 nm; and/or
a thickness of the third cladding layer is from 2 to 25 nm.
14. The secondary battery according to claim 1 , wherein
based on a weight of the positive electrode active material,
a content of element manganese ranges from 10 wt % to 35 wt %; and
a content of element phosphorus ranges from 12 wt % to 25 wt %.
15. The secondary battery according to claim 1 , wherein
a lattice change rate of the positive electrode active material having the core-shell structure is 4% or less.
16. The secondary battery according to claim 1 , wherein
an antisite defect concentration of Li/Mn of the positive electrode active material having the core-shell structure is 4% or less, is optionally 2.2% or less, and is more optionally from 1.5 to 2.2%.
17. The secondary battery according to claim 1 , wherein
a compaction density of the positive electrode active material having the core-shell structure under 3T is 2.2 g/cm 3 or more.
18. The secondary battery according to claim 1 , wherein a surface oxygen valence state of the positive electrode active material having a core-shell structure is −1.90 or less.
19. A battery module, comprising the secondary battery according to claim 1 .
20. A battery pack, comprising the battery module according to claim 19 .
21. An electrical apparatus, comprising the secondary battery according to claim 1 .