18650 lithium battery: standard voltage 3.7V, with small size, large capacity, mainly used in notebook computers and other high-end products. The 18650 is a steel-aluminum shell cell, and its technical aspects are relatively mature. The 18650 cell is a cylindrical cell with a diameter of 18mm and a height of 65mm, and its capacity is usually between 2000-3000mAh. The 18650 batteries used in most of the mobile power supplies on the market are lithium-cobalt-acid batteries. The single-cell nominal voltage is 3.7V and the charging voltage is 4.2V. Compared with the previous nickel-metal hydride and nickel-cadmium batteries, this type of battery has a larger capacity and a longer life, and the number of charge and discharge cycles can reach more than 500 times, and the safety factor is higher, non-toxic and environmentally friendly.