Lithium-ion batteries are secondary or rechargeable batteries that can last for thousands of cycles depending on the battery chemistry. Due to their unique properties, these batteries are used in a variety of applications, including electric and hybrid vehicles, electronics, energy storage systems, and other aerospace and military applications. The main components of lithium-ion batteries are:
- The positive pole (cathode), which determines the voltage and capacity of the battery and is usually a metal oxide,
- The negative pole (anode), which acts as a storage for lithium ions during charging and is usually made of carbon,
- The separator, which acts as an electrical insulator between the cathode and anode, preventing short circuits in the battery and at the same time allowing the transfer of lithium ions,
- The electrolyte, which is a solution of lithium salts, provides a medium for the transfer of ions between the cathode and anode.
Lithium-ion batteries work by flowing lithium ions from the positive electrode to the negative electrode through the electrolyte during charging. Electrons also flow from the positive electrode to the negative electrode, but they take a longer path around the external circuit. The electrons and ions combine at the negative electrode, and the lithium is stored at the anode. When no more ions are flowing, the battery is fully charged and ready for use. During discharging, the ions return from the negative electrode to the positive electrode through the electrolyte. Electrons also flow from the negative electrode to the positive electrode through the external circuit, producing energy. When all the ions have returned, the battery is fully discharged and needs to be recharged.