18650-HE2 3.6V 2500mah 20A Li Ion Battery Cell

The LG HE2 18650 battery is still a popular choice because of the high discharge rate of 20A and economical price. 

This battery is only rated at 20A, and can probably sustain 35A in 1-second pulses, similar to Samsung 25R, largely used for electric scooters, ebike, motorcycles, etc. PLS, as one of lithium ion battery suppliers, offer loose cells and customized li ion battery packs according to customers' requirements.  Or you can choose INR18650 F1L as well.