So [Travis] decided to upgrade it to make use of the ever-so-common, 18650 lithium-ion battery. Not looking to purchase any components [Travis] performed this hack using simple recycled household ...

French researchers have announced a prototype of an 18650 sodium-ion ... density and over 2,000 recharge cycle life span. By comparison, a typical lithium-ion battery has around 110 Wh/kg and ...