Would those work?
Panasonic NCR18650B_1 18650 Li-Ion Akku: Amazon.de: Elektronik
18650 battery unprotected | eBay
2 Sony VTC4 30A 3 7V 2100 mAh High Drain 18650 Unprotected Batteries | eBay
2pcs Panasonic NCR18650PF 3 6V 2900mAh 10A Rechargeable Battery Unprotected | eBay
2 New Efest...