Make sure you follow the USPS rules or you might end up not being able to ship.

Mailed Without Equipment. The following additional restrictions apply to the mailing of secondary cells or batteries without equipment:
1. The secondary lithium cells and batteries must be mailed in “the originally sealed packaging” and no more than three batteries.

2. The sealed packages of batteries must be separated and cushioned to prevent short circuit, movement, or damage.



3. The shipment must be contained in a strong enough sealed package to prevent crushing of the package or exposure of the contents during normal handling in the mail.

4. The outside of the package must be marked on the address side “Package Contains Lithium-ion Batteries (no lithium metal).”

DMM 601 Mailability