Secondary battery

Abstract

Secondary battery, characterized in that the secondary battery comprises a positive electrode foil which is provided with a positive active material layer, wherein the positive active material layer contains a positive active material including the LNMO particles, wherein the primary particle size of the individual LNMO particle is between 1 and 8 µm, wherein the LNMO particles each contain manganese(III) ions and manganese(IV) ions, wherein the LNMO particles correspond to the equations as follows: X1%=90~99%, X2%=98.5~99%, namely X1 <X2;where X1 is defined as the molar fraction of manganese(IV) ions in the LNMO particle at a depth of 5 nm at the surface, based on the total mole of manganese(III) ions and manganese(IV) ions, while X2 is defined as the molar fraction of manganese(IV) ions in the LNMO particle at a depth of 100 nm at the surface, based on the total mole of manganese(III) ions and manganese(IV) ions, wherein the LNMO particle contains a doping element, including at least one element from Co, Cr, Fe, Al, Nb, Mo, Ta, W, Ti, Zr, V, Si, Mg, Sc, Cu, Zn, Ga, Sr, Y, Ru, Sn, Sb, Na, P.