Lithium batteries with you in the cabin have different rules than lithium batteries inside checked luggage.
Also cell phones don't need to be powered off while inside the cabin.
Also cell phones don't need to be powered off while inside the cabin.
The FAA specifies both lithium ion and lithium metal batteries need to be in carry-on bags only, not checked: https://www.faa.gov/hazmat/packsafe/more_info/?hazmat=7