The lithium battery 0.2c5a represents the current used to discharge the battery power for 5 hours.
C5 (this 5 should be the subscript) indicates the capacity that can be obtained by completely discharging the battery power in 5 hours. Since the discharge capacity of the battery has a great relationship with the discharge condition, it is necessary to simultaneously explain the discharge condition when the capacity is said. , C5 is the discharge condition. 0.2C5A indicates the current value, that is, if it takes 5 hours to discharge the battery, it is usually said that the 0.2C discharge actually refers to this thing. For example, C5=10Ah means that if the battery is discharged after 5 hours, the capacity of the battery is 10Ah, then the corresponding 0.2C5 A=0.2*10=2A.