Lithium-ion battery is a kind of secondary battery (rechargeable battery), which mainly depends on the movement of lithium ion between the positive electrode and the negative electrode. In the process of charging and discharging, Li+ is embedded and extracted between the two electrodes: during charging, Li+ is extracted from the positive electrode and embedded into the negative electrode through electrolyte, and the negative electrode is in a lithium-rich state; The opposite is true when discharging.

Lithium batteries are divided into lithium batteries and lithium-ion batteries. Both mobile phones and laptops use lithium-ion batteries, also known as lithium batteries. Batteries generally use lithium-containing materials as electrodes, which is the representative of modern high-performance batteries. Real lithium batteries are rarely used in daily electronic products because of their great danger.

Lithium-ion battery was first developed by Sony Corporation of Japan in 1990. It embeds lithium ions in carbon (petroleum coke and graphite) to form a negative electrode (traditional lithium batteries use lithium or lithium alloy as a negative electrode). LixCoO2, LixNiO2 and LixMnO4 are commonly used as cathode materials, and LiPF6+ divinyl carbonate (EC)+ dimethyl carbonate (DMC) is used as electrolyte.

Petroleum coke and graphite are nontoxic and rich in resources. Lithium ion is embedded in carbon, which overcomes the high activity of lithium and solves the safety problems of traditional lithium batteries. The positive electrode LixCoO2 can reach a high level in charge-discharge performance and service life, which reduces the cost. In short, improve the comprehensive performance of lithium-ion batteries. It is predicted that lithium-ion batteries will occupy a large market in 2 1 century.

The reaction formula of lithium-ion secondary battery during charging and discharging is LiCoO2+C=Li 1-xCoO2+LixC.