Patent ID: 8568925

Claim:
A lithium secondary battery comprising: a positive electrode having a positive-electrode active material capable of occluding and releasing lithium ions, a negative electrode having a negative-electrode active material capable of occluding and releasing lithium ions, a separator interposed between the positive electrode and the negative electrode, and an electrolyte having lithium-ion conductivity, wherein, the positive-electrode active material contains a lithium-containing nickel complex oxide; the negative-electrode active material contains a graphite material having a reversible capacity of 350 mAh/g or more and an irreversible capacity of 30 mAh/g or less; and a ratio Qc/Qa between an irreversible capacity Qc per unit area in a portion of the positive electrode that opposes the negative electrode and an irreversible capacity Qa per unit area in a portion of the negative electrode that opposes the positive electrode satisfies 0.5≦Qc/Qa<1.