SECONDARY BATTERY, METHOD FOR PREPARING CORRESPONDING POSITIVE ELECTRODE ACTIVE MATERIAL, BATTERY MODULE, BATTERY PACK, AND ELECTRICAL APPARATUS

1 . A secondary battery, comprising a positive electrode plate that comprises a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector and comprising a positive electrode active material; and an electrolyte solution; wherein the positive electrode active material is an active material having a chemical formula below with dications A and B

A x B 1-x MeO 2 or A x B 1-x MPO 4 ,

wherein

Me is selected from one or more of elements Mn, Fe, Ni, Co, V, Cu, or Cr;

M is selected from one or more of Mn, Fe, Ni, or Co;

A is K or Na,

B is Na or Li;

where an ionic radius of A is larger than that of B, and A and B are of different classes;

x is from 0.001 to 0.05; and

the electrolyte solution comprises an electrolyte salt of the dications A and B, where A and B are as defined in the positive electrode active material.

2 . The secondary battery according to claim 1 , wherein a molar concentration ratio of the two dications in the electrolyte solution is greater than or equal to a stoichiometric ratio of the two dications in the positive electrode active material.

3 . The secondary battery according to claim 1 , wherein the electrolyte salt of the dications is selected from at least one of an inorganic salt and an organic salt of two or more elements of lithium, sodium, and potassium, where the inorganic salt is selected from at least one of hexafluorophosphate, perchlorate, hexafluoroarsenate, tetrafluoroborate, or difluorophosphate; and the organic salt is selected from at least one of bis(oxalate)borate salt, difluoro(oxalato)borate salt, bis(fluorosulfonyl)imide salt, or bis(trifluoromethanesulfonyl)imide salt.

4 . The secondary battery according to claim 1 , wherein the positive electrode active material having a chemical formula of A x B 1-x MeO 2 is selected from at least one of an active material having a chemical formula of A x B 1-x NiO 2 , A x B 1-x MnO 2 , A x B 1-x CoO 2 , A x B 1-x Ni y Co z Mn 1-y-z O 2 , or A x B 1-x Ni y Co z Al 1-y-z O 2 , and a cladded product and a doped product thereof, where the A, B, and x are as defined in claim 1 ; 0≤z≤1, and 0≤y≤1.

5 . The secondary battery according to claim 1 , wherein the positive electrode active material having a chemical formula of A x B 1-x MPO 4 is selected from at least one active material having a chemical formula of A x B 1-x FePO 4 or A x B 1-x CoPO 4 ; where the A, B, and x are as defined in claim 1 .

6 . A method for preparing a positive electrode active material for the secondary battery according to claim 1 , comprising:

1) providing a precursor of a transition metal Me or M; and

2) fully mixing the precursor with a salt of a metal A or a salt of a metal B, grinding a mixture; then calcinating a ground powder, and then cooling to room temperature to obtain the positive electrode active material; and,

wherein the Me or M, A, and B are as defined in claim 1 .

7 . The method according to claim 6 , wherein the salt of the metal A or the salt of the metal B is at least one of carbonate or hydroxide.

8 . The method according to claim 6 , wherein a molar ratio of the precursor to the salt of the metal A or the salt of the metal B is 105%-109% of stoichiometric ratio thereof.

9 . A battery module, comprising the secondary battery according to claim 1 .

10 . A battery pack, comprising the battery module according to claim 9 .

11 . An electrical apparatus, comprising at least one of the secondary battery according to claim 1 , the battery module according to claim 9 , or the battery pack according to claim 10 .