Lithium ion (Li-ion) batteries feature high energy density, high capacity, light weight and high power. The voltage of cylindrical type is 3.7V and button type is 3.6V. Li-ion batteries are one of the most popular types of rechargeable battery for portable electronics, with one of the best energy densities, no memory effect, and a slow loss of charge when not in use.

Principle and Reactions:
When a lithium-based cell is discharging, the lithium is extracted from the anode and inserted into the cathode. When the cell is charging, the reverse occurs.

Positive reaction: LiCoO2→ Li1-xCoO2 + xLi+ + xe−
Negative reaction: xLi+ + xe− + 6C → LixC6
Total reaction: LiCoO2 + 6C → Li1-xCoO2 + LixC6