Which Type of Power Bank is Allowed on a Flight?

Generally, lithium-ion batteries carried on aircraft must not exceed 100Wh.  However, batteries up to 160Wh may be carried with the approval of the airline.
 
But power banks do not directly indicate the rated energy, only the capacity, input & output details. So we can use a formula to know how much capacity of the power bank can be brought on the plane:
 
Rated energy = battery voltage x capacity
 
For example ES16 the quick charging powerbank, capacity is 10000mAh, battery voltage is 5V, rated energy = 5V x 10000mAh = 50Wh, smaller than 100Wh.
 
So, the maximum battery voltage of a power bank is 5V, converted according to the formula, capacity = rated energy divided by voltage, 100Wh divided by 5V is equal to 20,000mAh, it means a power bank with a capacity of less than 20,000mAh can be brought on the plane.