TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Material: The negative electrode material is complex oxide, nitride or carbon material. The positive electrode material is lithium manganese complex oxide of a layered crystalline structure represented by formulae (I) or (II):where x is a lithium deficient quantity and x at least 0, preferably 0.03 less than x at most 0.5 or 0.1 less than x less than 0.33, y is a substitution quantity of Mn sites for a metal element M and y at least 0, preferably 0.03 less than y at most 0.5, and delta is oxygen deficient quantity and delta at most 0.2. The lithium deficient quantity is represented by a/b, where a and b are 1-30 respectively, and satisfies a relation of a less than b. The substitution quantity of Mn sites for the metal element M is represented by c/d, where c and d are 1-30 respectively, and satisfies the relation c less than d. The composition variation of lithium deficient quantity and substitution quantity of Mn sites for the metal element M is set within +/-5%. The substitution metal element (M) is transition metal element and/or metal element other than manganese, preferably cobalt, nickel, iron, aluminum, gallium, indium, vanadium, niobium, tantalum, titanium, zirconium, chromium and/or cerium.    TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Characteristics: The total irreversible capacity of negative electrode material is set to 10-45%, preferably 20-36% of the total capacity of the positive electrode material. The negative electrode material has weight obtained by dividing a capacity of 45% or less of total capacity of positive electrode material by irreversible capacity of negative electrode material per unit weight. During usage of carbon material as negative electrode material, the irreversible capacity of negative electrode material is represented by (Irreversible capacity) = -10.1 x (carbon content%) + (1006 to 1066). The ratio of total capacity of negative electrode material to total capacity of positive electrode material is 1-1.5.