Abstract: A positive active material, a secondary battery, a battery module, a battery pack, and an electrical device are disclosed. The positive active material includes a spinel-type lithium-manganese-containing composite oxide with a molecular formula of Li1+xAaMbXcMn2?a?b?c?xO4?t. In the molecular formula: A is a doping element for a manganese site of the spinel-type lithium-manganese-containing composite oxide; M is used for combining with O to form a second phase containing a polyoxyanion, and M includes one or more of B, C, N, Si, P, S, or Cl; X includes 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.

Abstract: A spinel-type nickel-manganese-lithium-containing composite oxide, a preparation method thereof, and a secondary battery and an electric apparatus containing the same are provided. A body material of the spinel-type nickel-manganese-lithium-containing composite oxide is represented by a general formula LixNiyMnzMmO4Qq, and both element P and one or more elements selected from elements Nb, W, and Sb are doped in the body material, where based on mass of the spinel-type nickel-manganese-lithium-containing composite oxide, doping content k of the element P satisfies 0.48 wt %?k?3.05 wt %, doping content g of the one or more elements selected from the elements Nb, W, and Sb satisfies 0.05 wt %?g?0.31 wt %, and 2?k/g?20. The secondary battery provided in this application has good high-temperature storage performance and high-temperature cycling performance.