Cylindrical battery: divided into lithium iron phosphate, lithium cobaltate, lithium manganate, cobalt and manganese mixed, ternary materials, different systems, the shell is divided into steel shell and polymer, different material system batteries have different advantages. At present, the cylinder is mainly composed of a steel-shell cylindrical lithium iron phosphate battery. The iron-lithium battery exhibits high capacity, high output voltage, good charge and discharge cycle performance, stable output voltage, high current discharge, electrochemical stability, and in use. Safety (no burning or explosion due to improper operation such as overcharging, overdischarging and short circuit), wide operating temperature range and environmental friendliness. Widely used in solar lamps, lawn lamps, backup energy, power tools, toy models.