POSITIVE ACTIVE MATERIAL, SECONDARY BATTERY, BATTERY MODULE, BATTERY PACK, AND ELECTRICAL DEVICE

1 . A positive active material comprising a spinel-type lithium-manganese-containing composite oxide with a molecular formula of Li 1+x A a M b X c Mn 2−a−b−c−x O 4−t , wherein, in the molecular formula:

A is a doping element for a manganese site of the spinel-type lithium-manganese-containing composite oxide, and A comprises one or more of V, Nb, Ta, Mo, W, Ru, Rh, Sn, Sb, Te, Tl, Pd, Bi, or Po;

M is used for combining with O to form a second phase containing a polyoxyanion, and M comprises one or more of B, C, N, Si, P, S, or Cl;

X comprises one or more of Mg, Al, Si, Ca, Sc, Ti, Cr, Fe, Co, Ni, Cu, Zn, or Zr; and

the molecular formula satisfies: −0.1≤x≤0.3, 0≤a≤0.2, 0≤b≤0.2, 0<c≤0.7, and 0≤t≤0.2.

2 . The positive active material according to claim 1 , wherein A comprises one or more of Nb, Ta, Mo, W, Ru, Te, or Tl.

3 . The positive active material according to claim 1 , wherein M comprises one or more of Si, S, or Cl.

4 . The positive active material according to claim 1 , wherein X comprises one or more of Al, Sc, Cr, Ni, Cu, Zn, or Ti; and/or c satisfies 0.1≤c≤0.6.

5 . The positive active material according to claim 1 , wherein

the spinel-type lithium-manganese-containing composite oxide comprises a first region and a second region distributed sequentially from a core of the composite oxide to an outer surface of the composite oxide;

based on a volume of the spinel-type lithium-manganese-containing composite oxide, a volume percent of the second region, denoted as p, is less than or equal to 50%;

based on a total mass of element A in the spinel-type lithium-manganese-containing composite oxide, a weight percent of the element A located in the second region is m;

based on a total mass of element M in the spinel-type lithium-manganese-containing composite oxide, a weight percent of the element M located in the second region is n, satisfying: m+n≥70%; and

optionally 10%≤p≤30%, and/or 80%≤m+n≤95%.

6 . The positive active material according to claim 1 , wherein

the molecular formula satisfies 0.001≤a≤0.1 and/or 0.001≤b≤0.1; and

optionally, 0.005≤a+b≤0.1.

7 . The positive active material according to claim 1 , wherein

a specific surface area of the spinel lithium-manganese-containing composite oxide is 0.01 m 2 /g to 1.5 m 2 /g, and optionally 0.1 m 2 /g to 1 m 2 /g.

8 . The positive active material according to claim 1 , wherein

an average particle diameter Dv 50 of the spinel-type lithium-manganese-containing composite oxide is 1 μm to 20 μm, and optionally 2 μm to 15 μm.

9 . The positive active material according to claim 1 , wherein

a and b in the molecular formula and the average particle diameter Dv 50 of the spinel-type lithium-manganese-containing composite oxide satisfy: 0.01≤(a+b)×Dv 50 ≤1.

10 . The positive active material according to claim 1 , wherein the spinel-type lithium-manganese-containing composite oxide possesses a monocrystalline particle morphology or a quasi-monocrystalline particle morphology; and/or

a grain shape of the spinel-type lithium-manganese-containing composite oxide is at least one of an octahedron, a truncated octahedron, or a chamfered truncated octahedron.

11 . A secondary battery comprising the positive active material according to claim 1 .

12 . A battery module, comprising the secondary battery according to claim 11 .

13 . A battery pack, comprising the battery module according to claim 12 .

14 . An electrical device, comprising the secondary battery according to claim 11 .

15 . An electrical device, comprising the battery module according to claim 12 .

16 . An electrical device, comprising the battery pack according to claim 13 .