A method of charging a battery, characterized in that, the method comprising: in an m th charge and discharge cycle, constant-current charging the battery with a first charging current I m until a first state of charge SOC 1 of the battery is reached, wherein the battery has a corresponding first cut-off voltage V 1; constant-current charging the battery with a second charging current I n until a second state of charge SOC 2 of the battery is reached, wherein the battery has a second cut-off voltage V 2 at the end of constant-current charging, and constant-voltage charging the battery with the second cut-off voltage V 2 to a fully charged state; wherein I m =I n +k×I n, 0<k≤1, n is an integer greater than or equal to 0, m is an integer that is greater than or equal to 2 and that is greater than n by at least two, and k has different values in at least two charge and discharge cycles; I n is a charging current of the battery or of another battery, which has the same model of the battery in charge, in a constant-current charging phase of an n th charge and discharge cycle, or a preset value, and in the constant-current charging phase of the n th charge and discharge cycle, the battery is constant-current charged only with the second charging current I n to a charging limit voltage U cl, or the battery is constant-current charged only with the second charging current I n to a third state of charge SOC 3, and has a third cut-off voltage V 3 corresponding to the third state of charge SOC 3; and SOC 1 is a state of charge of the battery or of another battery, which has the same model of the battery in charge, that is constant-current charged to the charging limit voltage U cl in an (m-1) th charge and discharge cycle, wherein SOC 1 ≤SOC 3 +S, SOC 3 -S≤SOC 2≤ SOC 3 +S≤100%, and 0≤S≤10%. in an m th charge and discharge cycle, constant-current charging the battery with a first charging current I m until a first state of charge SOC 1 of the battery is reached, wherein the battery has a corresponding first cut-off voltage V 1; constant-current charging the battery with a second charging current I n until a second state of charge SOC 2 of the battery is reached, wherein the battery has a second cut-off voltage V 2 at the end of constant-current charging, and constant-voltage charging the battery with the second cut-off voltage V 2 to a fully charged state; wherein I m =I n +k×I n, 0<k≤1, n is an integer greater than or equal to 0, m is an integer that is greater than or equal to 2 and that is greater than n by at least two, and k has different values in at least two charge and discharge cycles; I n is a charging current of the battery or of another battery, which has the same model of the battery in charge, in a constant-current charging phase of an n th charge and discharge cycle, or a preset value, and in the constant-current charging phase of the n th charge and discharge cycle, the battery is constant-current charged only with the second charging current I n to a charging limit voltage U cl, or the battery is constant-current charged only with the second charging current I n to a third state of charge SOC 3, and has a third cut-off voltage V 3 corresponding to the third state of charge SOC 3; and SOC 1 is a state of charge of the battery or of another battery, which has the same model of the battery in charge, that is constant-current charged to the charging limit voltage U cl in an (m-1) th charge and discharge cycle, wherein SOC 1 ≤SOC 3 +S, SOC 3 -S≤SOC 2≤ SOC 3 +S≤100%, and 0≤S≤10%.