Electronic devices powered by lithium batteries can catch fire if they are damaged or have exposed electrical terminals. Devices that smoke or catch fire are much easier to extinguish in the cabin than they are in the cargo hold. So, the FAA recommends that passengers keep cell phones and other devices nearby in the cabin, so they can quickly access them, if necessary.
However, even in carry-on baggage, spare lithium batteries should be protected from damage or short circuiting. Ensuring that the batteries are packed properly and are not touching or bumping something that could potentially cause them to spark. If batteries are not sealed in manufacturer packaging, the battery terminals should be protected by covering them with tape and placing them in separate bags to prevent short circuits.
Some of the other common toiletries that passengers may plan to pack, but that could be hazardous include: aerosol cans that may contain hair spray, deodorant, tanning spray or animal repellant; nail polish; artist paints; and glues.
For more detailed information about materials that should not fly, visit the FAA’s Hazardous Materials Safety website.
To be on the safe side, when in doubt, just leave it out!