NOVELTY - The method involves supplying a first current that flows between the first and second electrodes (201) in a first direction during a first period. A second current is supplied that flows between the first electrode and the second electrode in a second direction during a second period. The first direction and the second direction are opposite to each other and a reaction product (202a) grows on the first electrode by supplying the first current, and reaction product on the first electrode is dissolved by supplying the second current.    USE - Method of charging electronic device such as battery (claimed) such as lithium-ion secondary battery of mobile phone. Can also be used in charging secondary batteries such as lithium-ion polymer secondary battery, liquid circulation battery such as zinc-bromine battery and high-operating- temperature secondary batteries such as sodium-sulfur battery lithium -iron sulfide battery, coin-type secondary battery, laminated secondary battery, cylindrical secondary battery and rectangular secondary battery of electrical devices such as display devices of televisions, monitors, desktop PC, word processors, image reproduction devices, portable or stationary music reproduction devices such as compact disc players and digital audio players, portable or stationary radio receivers, recording reproduction devices car phones, portable or stationary game machines etc.    ADVANTAGE - The degradation of a battery is prevented or the degree of the degradation is reduced by applying a signal to supply a current reverse to a current with which a reaction product is formed during charge. Thus, the charge and discharge performance of the battery is maximized for a long time. The long-term reliability of battery is secured and increased. The maintenance-free battery is employed and efficiency of the charge and discharge of battery is increased to reduce the size of a battery.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for an electronic device.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of the reaction product formed on electrode.    Electrode (201)    Reaction product (202a)    Electrolytic solution (203)