Lithium-ion battery: It is a secondary battery (rechargeable battery), which mainly relies on lithium ions to move between the positive and negative electrodes to work. During charge-discharge, Li+ is embedded and de-embedded back and forth between the two electrodes: on charging, Li+ is de-embedded from the positive electrode and embedded in the negative electrode through the electrolyte, where the negative electrode is in a lithium-rich state; opposite when discharged. Since the commercialization of lithium-ion batteries, due to their high energy density, high working voltage, no memory effect, long cycle life, no pollution to the environment and many other advantages, they have been widely used as the power supply for various mobile devices, thus quickly entering the large-scale practical stage.