METHOD FOR CHARGING NONAQUEOUS ELECTROLYTE SECONDARY CELL

摘要

A method for charging a secondary cell comprising positive and negative electrodes both containing a material capable of absorbing/releasing lithium and a binder polymer, at least one separator for isolating the positive and negative electrodes from each other, and a nonaqueous electrolyte containing a lithium salt. Charging patterns Pn[Xn, tn], Pn+1[Xn+1, tn+1], Pn+2[Xn+2, tn+2], Pn+3[Xn+3, tn+3] (n is an integer of one or more) for each of which the current value (X amperes, X >= 0 ampere) and the charging time (t seconds, t <> 0 second) are specified are combined in order of mention to charge the secondary cell. The current values (X amperes) of consecutive two charging patterns (P) are different from each other. The current values Xn+2, Xn of the charging pattern Pn[Xn, tn], Pn+2[Xn+2, tn+2] are Xn+2 <= Xn. Xn+2, Xn, tn+2, tn satisfy the expression below. Therefore, high-rate small-loss, efficient charging is possible, high-speed charging is possible, and the cycle life can be prolonged.