Lithium-ion battery is a type of secondary battery (rechargeable battery) that works mainly by moving lithium ions between the positive and negative terminals. In the process of charge and discharge, Li+ is embedded and deembedded between the two electrodes. During charging, Li+ is deembedded from the positive electrode and embedded into the negative electrode through the electrolyte, and the negative electrode is in a lithium-rich state. The opposite is true for electrical discharge.

Lithium batteries are divided into lithium batteries and lithium ion batteries. Mobile phones and laptops use lithium-ion batteries, commonly known as lithium-ion batteries. The battery generally uses the material containing lithium element as the electrode, is the representative of modern high performance battery. Real lithium-ion batteries are rarely used in everyday electronics because they are dangerous.

Lithium-ion batteries were first developed by SONY in 1990. It involves embedding lithium ions into carbon (petroleum coke and graphite) to form a negative electrode (conventional lithium-ion batteries use lithium or lithium alloys as the negative electrode). LixCoO2, LixNiO2 and LixMnO4 are commonly used as positive materials, and LiPF6+ diethylene carbonate (EC) + dimethyl carbonate (DMC) as electrolytes.

Petroleum coke and graphite as anode materials are non-toxic and have sufficient resources. Lithium ion embedded in carbon overcomes the high activity of lithium and solves the safety problems existing in traditional lithium batteries. The positive LixCoO2 can reach a high level in charging and discharging performance and life, which reduces the cost and improves the comprehensive performance of lithium ion batteries. Lithium-ion batteries are expected to occupy a large market in the 21st century.

The equation for lithium-ion secondary battery charging and discharging is as follows.