A lithium-ion battery is a rechargeable battery that stores electrical energy in chemical form and releases it when needed. During charging and discharging, lithium ions move between its electrodes while electrons travel through an external circuit. These batteries are used in electronics, electric vehicles, and residential, commercial, and utility-scale energy-storage systems.
What Is a Lithium-Ion Battery?
A lithium-ion battery consists of one or more electrochemical cells. A typical cell contains a positive electrode, a negative electrode, an electrolyte, a separator, and current collectors. These components work together to allow lithium ions to move inside the cell while electrons flow through an external circuit.
The term lithium-ion refers to a family of rechargeable battery technologies rather than one single chemistry. Different electrode materials give different chemistries their own characteristics, including differences in energy density, power capability, cycle life, and other performance properties.
In an energy-storage system, cells are grouped into modules, packs or racks. These are combined with a battery management system, power-conversion equipment, thermal management, protection equipment and system controls to form a complete battery energy storage system (BESS). In simple terms, a cell stores energy, while a BESS manages, converts and delivers it.
Before discussing the components inside a lithium-ion cell, it is helpful to first understand how a lithium-ion battery differs from the broader term “lithium battery.