Airline Passengers and Batteries - FAA

What the official page says

Rechargeable batteries with a capacity of 0-100 Wh are allowed on passenger aircraft, while those with a capacity of 101-160 Wh require approval from the air carrier, and batteries exceeding 160 Wh are forbidden. Spare lithium batteries (including power banks and portable chargers) must be carried on and cannot be checked. For lithium-ion rechargeable batteries with a capacity of 101-160 watt-hours per battery, there is a limit of two spare batteries (including power banks and portable chargers) per person. Based on US DOT regulations (49 CFR, Sec. 175.10). Transportation Security Administration (TSA) security, individual airline, and international rules may, at times, be more restrictive.