Patent ID: 8334074

Claim:
A nonaqueous electrolyte secondary battery comprising a positive electrode comprising a lithium-nickel complex oxide, a negative electrode comprising a lithium-titanium complex oxide and a lithium-containing phosphorous oxide, and a nonaqueous electrolyte, the battery satisfying the following equations (1) to (5): b/a<y/x (1) 75 ≦b/a≦ 90 (2) 90 ≦y/x≦ 100 (3) x<z (4) 0<γ/β≦( ay−bx )/ bz (5) where; a is a lithium-deintercalation capacity [mAh/g] of the lithium-nickel complex oxide in the first charge; b is a lithium-intercalation capacity [mAh/g] of the lithium-nickel complex oxide in the first discharge; x is a lithium-intercalation capacity [mAh/g] of the lithium-titanium complex oxide in the first charge; y is a lithium-deintercalation capacity [mAh/g] of the lithium-titanium complex oxide in the first discharge; z is a lithium-intercalation capacity [mAh/g] of the lithium-containing phosphorous oxide; β a is a mass [g] of the lithium-titanium complex oxide; and y is a mass [g] of the lithium-containing phosphorous oxide; wherein the lithium-titanium complex oxide is lithium titanate having a spinel structure represented by the formula Li 4+x Ti 5 O 12 , the lithium-containing phosphorous oxide is at least one oxide selected from Li s Fe 1-t Mn t PO 4 , and Li s CoPO 4 and has an olivine structure, wherein x is from −1 to 3, s is from greater than 0 to 1.15, t is from 0 to 1, and s is from greater than 0 to 1.15.