A lithium secondary battery is provided with a positive electrode, a
negative electrode, and a non-aqueous electrolyte prepared by dissolving
a solute in a non-aqueous solvent wherein a positive electrode active
material of said positive electrode is composed of lithium-manganese
composite oxide having a spinel structure and lithium-transition metal
composite oxide having a layer structure containing at least nickel and
lithium salt having oxalato complex as anion is admixed to said
non-aqueous electrolyte.