Lithium-ion batteries are high-capacity rechargeable batteries developed in the 1990s. The main positive electrode for lithium-ion batteries are lithium cobalt oxide, lithium manganese oxide, ternary nickel-manganese-cobalt materials, and lithium iron phosphate. Lithium iron (LiFePO4) is highly regarded as the most promising positive electrode material for lithium-ion batteries, especially for power lithium-ion batteries, due to its high, stable cycling performance, low cost, stable discharge platform, and environmental friendliness. It has become a hot spot for current research and development. A lithium iron battery is a lithium-ion battery that uses lithium iron phosphate as the positive electrode material. The main positive electrode materials for lithium-ion batteries include lithium cobalt oxide, manganese oxide, lithium nickel oxide, ternary materials, and lithium iron phosphate. Among these, lithium cobalt oxide is the most commonly used positive electrode material in lithium-ion batteries today. From the perspective of material principles, lithium iron phosphate is also an insertion and de-insertion process, which is the same as lithium cob oxide and lithium manganese oxide.