| 摘要 |
PURPOSE:To provide a good cycle characteristic even if a specific charging voltage is set high by charging a battery stepwise while gradually reducing charging currents after the battery is first charged at a constant current and at the specific charging voltage. CONSTITUTION:A specific charging voltage for charging an Li-ion secondary battery need be set high because the battery voltage of the Li-ion secondary battery is high. If the battery is held at a high voltage during charging, the battery performance is deteriorated. Therefore, the battery is charged at a charging current I1 for the first step of charging until the specific charging voltage is reached, and the charging current is reduced immediately after the specific charging voltage has been reached. When the charging current is reduced, the polarization of electrodes is temporarily decreased, and the voltage is decreased to below the specific charging voltage. Thereafter, the battery undergoes constant current charging with a reduced charging current I2 for the second step of charging until the specific charging voltage is reached again, and the charging current is reduced after the specific charging voltage has been reached. Such charging is repeated to (n) steps. |
