A polymer lithium ion battery is a secondary battery (rechargeable battery) that mainly relies on lithium ions moving between a positive electrode and a negative electrode to operate. During charge and discharge, Li+ is intercalated and deintercalated between the two electrodes: when charging, Li+ is deintercalated from the positive electrode, and the electrolyte is embedded in the negative electrode, and the negative electrode is in a lithium-rich state;
　　 Lithium batteries are classified into lithium batteries and polymer lithium ion batteries. Both mobile phones and laptops use polymer lithium-ion batteries, which are commonly referred to as lithium batteries. The battery generally uses a lithium-containing material as an electrode and is representative of modern high-performance batteries. True lithium batteries are rarely used in everyday electronics because of their high risk.
　　 A polymer lithium ion battery is formed by embedding lithium ions in carbon (petroleum coke and graphite) to form a negative electrode (lithium for a conventional lithium battery or lithium alloy as a negative electrode). The positive electrode material is commonly used for LixCoO2, LixNiO2, and LixMnO4, and LiPF6+diethylene carbonate (EC) + dimethyl carbonate (DMC) for the electrolyte.
　　 Petroleum coke and graphite as non-toxic materials are non-toxic and have sufficient resources. Lithium ions are embedded in carbon, which overcomes the high activity of lithium and solves the safety problems of traditional lithium batteries. The positive LixCoO2 can reach the charge and discharge performance and life. The higher the level, the lower the cost, and the overall performance of the lithium-ion battery is improved. It is expected that lithium-ion batteries will occupy a large market in the 21st century. The reaction formula for charging and discharging lithium ion secondary batteries is LiCoO2+C=Li1-xCoO2+LixC