NOVELTY - A battery comprises cathode (11), anode (12) and electrolyte having electrolytic solution (s1) containing ternary system copolymer with weight average molecular weight of 0.6-1.5 million and having vinylidene fluoride, hexafluoropropylene (4-7.5 wt.%), and monomethylmaleate (0.3-2 wt.%). The solution (s1) contains solvent and electrolyte salt (0.8-1.7 mol/kg). The cathode has active material and binder having polymer with vinylidene fluoride; and anode has active material and binder having binary system copolymer with vinylidene fluoride and monomethylmaleate (0.3-2 wt.%).    USE - As battery (claimed) useful in portable electronic devices such as combination camera (video tape recorder), mobile phone, and notebook personal computer.    ADVANTAGE - In the battery, the electrolyte is gel electrolyte with improved liquid retaining characteristics, thus the contact characteristics of the electrolyte to the cathode and the anode are improved which provides superior battery characteristics. The cathode binder in the cathode contains the polymer containing vinylidene fluoride as a component, and the contact characteristics of the electrolyte to the cathode are improved compared to the case that the cathode binder does not contain the polymer containing vinylidene fluoride as a component. The vinylidene fluoride, and monomethylmaleate acid ester makes the contact characteristics of the anode to the electrolyte stable, and the contact characteristics of the anode active material layer to the anode current collector is improved. In the battery the concentration of the electrolyte salt is high, the liquid retaining characteristics of the electrolyte are improved, thus the contact characteristics of the electrolyte to the cathode, anode and separator are improved, therefore even when a defect such as a break exists in the film package member, the electrolytic solution is hardly leaked and the battery capacity, the cycle characteristics, and the load characteristics are improved, providing superior battery characteristics.    DETAILED DESCRIPTION - A battery comprises cathode (11), anode (12) and electrolyte having electrolytic solution (s1) and ternary system copolymer with weight average molecular weight of 0.6-1.5 million and having vinylidene fluoride, hexafluoropropylene (4-7.5 wt.%), and monomethylmaleate acid ester (0.3-2 wt.%). The solution (s1) contains solvent and electrolyte salt (0.8-1.7 mol/kg). The cathode contains active material and binder of polymer having vinylidene fluoride; and anode contains active material and binder of binary system copolymer having vinylidene fluoride and monomethylmaleate acid ester (0.3-2 wt.%). The cathode, anode, and the electrolyte are contained inside a film-shaped package member (30).    DESCRIPTION OF DRAWING(S) - The figure shows an exploded perspective view the battery.    Cathode (11)    Anode (12)    Electrode body (20)    Package member (30)    Adhesive film. (31)