1, the battery is not a resistance, so it can not be simply calculated with Ohm's law.
2, when using a mobile phone to charge a mobile phone battery, the size of the current is controlled by the charging circuit inside the mobile phone, as long as the charging capacity of the charger is large enough.
3, use the charger to directly charge the mobile phone battery, charging current mainly depends on the output current of the charger, different chargers charge the same battery when the current is not the same.