Lithium ion batteries are a huge fire hazard. You cannot carry them on passenger airplanes if you're shipping them. They are "Cargo Aircraft Only" hazmat.

So Boeing decides to put 2 (!) 49 kg lithium ion batteries on their plastic airplane. You tube "lithium ion battery fires" for an eye opener. At least two cargo airplanes have burned to the ground because of lithium ion battery fires.

Great thinking there.