Ledlenser 880621 14500 3.7V Lithium Ion (Li-ion) Flat-Top Battery for the ML4, MH4, MH5, iH5R, P5R Core and P5R Work. $24.95. Li-Ion (Lithium-Ion) batteries are a type of rechargeable battery. Lithium ion batteries are one of the most common rechargeable batteries in portable electronics. Lithium ion batteries have one of the best energy