An advanced battery technology known as a lithium-ion (Li-ion) battery makes use of lithium ions as a crucial component of its electrochemistry. Lithium atoms in the anode are ionized and separated from their electrons during a discharge cycle. From the anode, the lithium ions move through the electrolyte until they reach the cathode, where they reunite with their electrons and neutralize the electrical charge. Between the anode and cathode, a micro-permeable separator allows the lithium ions to move through. Li-ion batteries are able to have a very high voltage as well as charge storage per unit mass and volume in part due to lithium’s small size—it ranks third only to hydrogen and helium.

As electrodes, Li-ion batteries can make use of a variety of materials. The combination of graphite (anode) and lithium cobalt oxide (cathode), which is most frequently found in portable electronic devices like cellphones and laptops, is the most common. Lithium iron phosphate and lithium manganese oxide, both of which are utilized in electric and hybrid automobiles, are additional cathode materials. The electrolyte of most Li-ion batteries is typically ether, a class of organic compounds.