US Patent 7622222 Nonaqueous electrolyte secondary battery and manufacturing method thereof

A nonaqueous electrolyte secondary battery including a positive electrode 2 containing a positive electrode active material comprising a lithium-transition metal oxide having a layered structure, a negative electrode 1 and a nonaqueous electrolyte, wherein a surface treatment layer containing a compound represented by the chemical formula MlPmOn (wherein M is at least one element which can have a valence of 2, and l, m and n are integers in a range satisfying 2l+5m=2n) is formed on at least a part of the surface of the positive electrode active material.