Portable electronics use batteries as a power source. With the rapid development of portable products, the amount of various batteries has increased, and many new batteries have been developed. In addition to the familiar high-performance alkaline batteries, rechargeable nickel-cadmium batteries, and nickel-hydrogen batteries, there are also lithium batteries developed in recent years. This article focuses on the basics of lithium batteries. This includes its characteristics, main parameters, the meaning of the model, the scope of application and precautions for use.