Positive electrode active substance for lithium secondary battery, positive electrode for lithium secondary battery and lithium secondary battery, and methods for producing these

A positive electrode active substance for a lithium secondary battery, comprising a coated positive electrode active substance wherein a surface of a positive electrode active substance is directly coated with lithium metaphosphate,

• wherein the positive electrode active substance comprises at least one selected from:
• a lithium transition metal composite oxide comprising at least one transition metal element selected from nickel, cobalt and manganese;
• a lithium transition metal composite oxide obtained by replacing a part of a transition metal of the above lithium transition metal composite oxide by at least one element selected from Sn, Mg, Fe, Ti, Al, Zr, Cr, V, Ga, Ge, Sm, Zn, Cu, Bi, Mo and La, or/and replacing a part of oxygen atoms by S;
• a phosphoric acid compound having an olivine structure;
• an active substance obtained by coating a surface of the positive electrode active substance with an oxide containing any of the above elements;
• the lithium metaphosphate is chemically bound to the surface of the positive electrode active substance;
• and
• a mass ratio (A/B) of the lithium metaphosphate (A) with respect to the positive electrode active substance (B) is 0.001 to 0.10.

A positive electrode active substance for a lithium secondary battery, comprising a coated positive electrode active substance wherein a surface of a positive electrode active substance is directly coated with lithium metaphosphate,

• wherein the positive electrode active substance comprises at least one selected from:
• a lithium transition metal composite oxide represented by one of the following composition formulas:
• Li1+aNixMnyO2 (0<a≤0.5, 0<x<1, 0<y<1),
• Li1+aNixMnyMzO2 (0<a≤0.5, 0<x<1, 0<y<1, 0<z<1, and M is Co or/and Fe),
• LiCo1-xNixO2 (0.01<x<1),
• LiNixCoyMnzO2 (x+y+z=1, 0.01<x, 0.01<y, 0.01<z), and
• LiNiβCoγAlδO2 (β+γ+δ=1, 0.7≤β<1, 0<γ≤0.2, 0<δ≤0.1);
• a lithium transition metal composite oxide obtained by replacing a part of at least one element of Ni, Co and Mn of the above lithium transition metal composite oxide by at least one element selected from Sn, Mg, Fe, Ti, Al, Zr, Cr, V, Ga, Ge, Sm, Zn, Cu, Bi, Mo and La, or/and replacing a part of oxygen atoms by S;
• an active substance obtained by coating a surface of the positive electrode active substance with an oxide containing any of the above elements;
• the lithium metaphosphate is chemically bound to the surface of the positive electrode active substance;
• and
• a mass ratio (A/B) of the lithium metaphosphate (A) with respect to the positive electrode active substance (B) is 0.001 to 0.10.