TravelScoot's single capacity Li-Ion battery contains 24 gram lithium and is approved for air travel.
The complete text of 49 CFR 175.10 is at
http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=1cbbd60e3b9ad751579279fd251f54b3&rgn=div8&view=text&node=49:22.214.171.124.126.96.36.199&idno=49. Sections 17 and 18 apply to the lithium ion batteries. I have excerpted the text below:
(17) A lithium ion battery-powered wheelchair or other mobility aid as follows:
(i) A wheelchair or other mobility aid equipped with a lithium ion battery, when carried as checked baggage, provided—
(A) The lithium ion battery must be of a type that successfully passed each test in the UN Manual of Tests and Criteria as specified in §173.185 of this subchapter, unless approved by the Associate Administrator;
(B) Visual inspection of the wheelchair or mobility aid reveals no obvious defects;
(C) Battery terminals must be protected from short circuits ( e.g., by being enclosed within a battery container that is securely attached to the mobility aid);
(D) The pilot-in-command is advised, either orally or in writing, prior to departure, as to the location of the wheelchair or mobility aid aboard the aircraft; and
(E) The wheelchair or mobility aid is loaded, stowed, secured and unloaded in an upright position and in a manner that prevents unintentional activation and protects it from damage.
(F) A lithium metal battery is forbidden aboard a passenger-carrying aircraft.
(ii) A wheelchair or other mobility aid when carried as checked or carry-on baggage, provided—
(A) The wheelchair or other mobility aid is designed and constructed in a manner to allow for stowage in either a cargo compartment or in the passenger cabin;
(B) The lithium ion battery and any spare batteries are carried in the same manner as spare batteries in paragraph (a)(18) of this section.
(C) The lithium ion battery and any spare batteries are carried in the same manner as spare batteries in paragraph (a)(18) of this section.
(18) Except as provided in §173.21 of this subchapter, portable electronic devices (for example, watches, calculating machines, cameras, cellular phones, lap-top and notebook computers, camcorders, etc.) containing cells or batteries (including lithium cells or batteries) and spare batteries and cells for these devices, when carried by passengers or crew members for personal use. Each spare battery must be individually protected so as to prevent short circuits (by placement in original retail packaging or by otherwise insulating terminals, e.g. , by taping over exposed terminals or placing each battery in a separate plastic bag or protective pouch) and carried in carry-on baggage only. In addition, each installed or spare battery must not exceed the following:
(i) For a lithium metal battery, a lithium content of not more than 2 grams per battery; or
(ii) For a lithium-ion battery, an aggregate equivalent lithium content of not more than 8 grams per battery, except that up to two batteries with an aggregate equivalent lithium content of more than 8 grams but not more than 25 grams may be carried.