The internal structure of LiFePO4 battery: LiFePO4 with olivine structure on the left is used as the positive electrode of the battery. The aluminum foil is connected with the positive electrode of the battery. The middle is the separator of the polymer. It separates the positive electrode from the negative electrode, but the lithium ion Li+ can pass and the electron e- Can not pass, the right side is a battery negative electrode composed of carbon (graphite), connected by copper foil to the negative electrode of the battery. Between the upper and lower ends of the battery is the electrolyte of the battery, and the battery is hermetically sealed by a metal casing. When the LiFePO4 battery is charged, the lithium ion Li+ in the positive electrode migrates toward the negative electrode through the polymer separator; during the discharge, the lithium ion Li+ in the negative electrode migrates toward the positive electrode through the separator. Lithium-ion batteries are named after the lithium ions migrate back and forth during charging and discharging. The nominal voltage of the LiFePO4 battery is 3.2 V, the termination charging voltage is 3.6 V, and the termination discharge voltage is 2.0 V. Due to the quality and process of the positive and negative materials and electrolyte materials used by various manufacturers, there will be some differences in their performance. For example, the same model (standard battery of the same package) has a large difference in battery capacity (10% to 20%).