A method for charging a battery includes charging the battery with a charging current at a constant current during an mth charge and discharge cycle; a first state of charge SOC1 of the battery when the constant current charging phase in any one charge and discharge cycle ends is the same as a standard state of charge SOC0, SOCb≤SOC0≤SOCa+k. SOCa is a state of charge or a preset value of the battery at the end of the constant current charging phase during an nth charge and discharge cycle, SOCb is a state of charge or a preset value of the battery at the end of the constant current charging phase during an (m−1)th charge and discharge cycle, SOCb≤SOC0≤SOCa+k, 0≤k≤10%, and SOCa+k≤100%.