You will need to check the wheelchair in when boarding, to store it in the airplanes baggage compartment. You will not be able to check it in with the Lithium Ion battery connected. You must disconnect the battery, store it in the black travel pouch that comes with your wheelchair, and bring it with you in your Carry On bag. The DOT (Department of Transportation) regulates the allowance of lithium ion batteries
that can be taken onto an airplane by the Equivalent Lithium Content (ELC) of the batteries. Some airlines may have their own restrictions, so it is always best to check with the specific airline you are flying. Most will be compassionate enough to allow it, as it does meet the DOT regulations and it is a mobility aid that is essential to your travel.