NOVELTY - A secondary battery comprises a positive electrode containing a positive-electrode active-material layer which contains positive-electrode active material, a negative electrode containing negative-electrode active-material layer which contains a negative-electrode active material, and an electrolyte. The positive-electrode active material contains a lithium-iron-phosphate compound having olivine structure or lithium-manganese composite oxide having spinel structure. The negative-electrode active material contains a titanium-containing inorganic oxide.    USE - Secondary battery is used for battery pack of electronic device, electric vehicle, electrical storage apparatus for electric power information-control apparatus and electric power system (all claimed). Uses include but are not limited to notebook computer, portable information terminal, cordless phone subunit, digital still camera, navigation system, memory card, electric shaver, refrigerator, dryer, toy, etc.    ADVANTAGE - The secondary battery has suppressed gas evolution and deterioration of cycle characteristics.    DETAILED DESCRIPTION - A secondary battery comprises a positive electrode containing a positive-electrode active-material layer which contains positive-electrode active material, a negative electrode containing negative-electrode active-material layer which contains a negative-electrode active material, and an electrolyte. The positive-electrode active material contains a lithium-iron-phosphate compound having olivine structure or lithium-manganese composite oxide having spinel structure. The negative-electrode active material contains a titanium-containing inorganic oxide. The ratio of surface area (cm2) of the positive electrode and surface area of the negative electrode is 1.005-1.08. The ratio of positive electrode charge capacity (mAh/cm2) per unit area to the initial negative electrode charge capacity per unit area is 1.03 or more. The ratio of irreversible capacity per unit area of the positive electrode to irreversible capacity per unit area of the negative electrode is 0.9-1.1. INDEPENDENT CLAIMS are included for the following:    (1) battery pack;    (2) electronic device;    (3) electric vehicle; and    (4) electrical storage apparatus for electric power information-control apparatus and electric power system.    DESCRIPTION OF DRAWING(S) - The drawing shows the schematic view of the structure of secondary battery. (Drawing includes non-English language text)    Cladding material (31)    Exterior portions (31A,31B)    Positive electrode tab (32)    Negative electrode tab (33)    Adhesive film (34)