Lithium batteries usually have two appearances: cylindrical and square. The inside of the battery adopts a spiral wound structure, and is formed by spacing a positive and negative electrode with a very fine and highly permeable polyethylene film insulation material. The positive electrode includes a current collector composed of lithium cobaltate (or lithium nickel cobalt manganate, lithium manganate, lithium iron phosphate, etc.) and an aluminum foil. The negative electrode is composed of a current collector composed of a graphitized carbon material and a copper foil. The battery is filled with an organic electrolyte solution. Safety valves and PTC components (partially cylindrical) are also included to protect the battery from damage during abnormal conditions and output short circuits.
The voltage of a single-cell lithium battery is 3.7V (3.2V for lithium iron phosphate anode), and the battery capacity cannot be infinite. Therefore, single-cell lithium batteries are often processed in series and parallel to meet the requirements of different occasions.