Abstract: The present application proposes a composite separator, including: a base membrane, a first nanofiber layer, and a ceramic powder. The first nanofiber layer is positioned on a first side of the base membrane. The ceramic powder forms a first ceramic coating positioned between the first nanofiber layer and the base membrane, or, the ceramic powder is added to the first nanofiber layer. In addition, the present application further proposes a method for preparing the composite separator, and a battery.

Abstract: Provided in the present invention is a multi-element co-doped sodium-ion positive electrode material, which is characterized in that the phase of the positive electrode material is an O3 phase, the space group thereof is R-3m, and the chemical formula thereof is Na?MaLibCucTidO2+?, wherein M is at least one of Ni, Co, Mn, Cr, V, Al, Fe, B, Si, Mg and Zn, 0.5???1, ?0.1???0.1, 0<a<0.95, 0<b<0.25, 0<c<0.3, 0<d<0.6, a+b+c+d=1, and the charge neutrality condition is met. Also provided in the present invention is a preparation method for and the use of the multi-element co-doped sodium-ion positive electrode material.