Lithium-ion batteries are known as the “engine of the modern energy revolution”, from cell phones, drones, home energy storage batteries to electric vehicles, its technology supports the global intelligent process. By 2023, the global lithium-ion battery market size has exceeded $100 billion, with an annual growth rate of more than 15%. In this article, we will use the most intuitive way to analyze its internal structure, and reveal how it realizes efficient charging and discharging through “lithium ion migration”.