NOVELTY - A battery comprises cathode (11); anode (12) arranged opposite of the cathode; and an electrolyte in between the cathode and the anode, where the amount of cathode active material and the amount of anode active material is such that the open circuit battery voltage is 4.25 to 6 volts, the electrolyte contains an electrolytic solution and a polymer containing vinylidene fluoride, the cathode contains lithium complex oxides.    USE - As battery (claimed) used as a power source for the portable electronic devices such as combination cameras, mobile phones and portable computers.    ADVANTAGE - The battery is capable of improving the energy density and improving cycle characteristics. Since the open circuit voltage in a full charge state per a pair of the cathode and the anode is 4.25 to 6 volts, a high energy density can be obtained. Further, since the electrolyte contains a polymer containing vinylidene fluoride as a component, oxidation and decomposition reaction in the vicinity of the cathode surface can be inhibited even when the open circuit voltage in full charge is raised, and the battery characteristics such as cycle characteristics can be improved. The oxidation stability of the electrolyte is improved, and superior cycle characteristics could be obtained. Similar effect could be obtained even when other cathode active material is used and even when the mixture of cathode active materials is used.    DETAILED DESCRIPTION - A battery comprises cathode (11); anode (12) arranged opposite of the cathode; and an electrolyte in between the cathode and the anode, where the amount of cathode active material and the amount of anode active material is such that the open circuit battery voltage is 4.25 to 6 volts, the electrolyte contains an electrolytic solution and a polymer containing vinylidene fluoride, the cathode contains lithium complex oxides Lir'Co(1-s')M'sO(2-t')Fu', where M' is at least one element selected from nickel, manganese, magnesium, aluminum, boron, titanium, vanadium, chromium, iron, copper, zinc, molybdenum, tin, calcium, strontium and tungsten, r' is 0.8 to 1.2, s' is 0 to 0.5, t' is -0.1 to 0.2 and u' is 0 to 0.1.    DESCRIPTION OF DRAWING(S) - The figure shows secondary battery.    Spirally wound electrode body (10)    Cathode lead (11)    Anode lead (12)    Film package member (20)    Adhesive film (21)