Lithium battery by air

i am a nail technician and im trying to bring my nail electic drill which contains lithium battery from florida to japan but i have to transfer airplane so i'll have to go to shanghai and layover is 13 hours so i'll go sightseeing. do they take away my electric drill? last time i had a portable phone charger and they took it in china so im scared because the electric drill is like $400. i checked all the airlines website but it says as long as i have it in my purse, it's ok. but im going to a city from airport in shanghai so im not sure if there is a special rule...