先进磷酸铁锂正极高效储锂设计与调控
摘要
<p indent="0mm">Lithium ion batteries (LIBs) have the advantages of high energy density, good cycling stability, and no memory effect, and have been widely used in various fields such as portable electronic products, electric vehicles, smart grids, and others. Among the numerous cathode materials for lithium-ion batteries, the polyanion cathode material has the advantages of easy production and low cost, as well as a theoretical voltage range of <sc>2.0–4.8 V,</sc> making it an excellent cathode material. LiFePO<sub>4</sub> has become the most widely used cathode material due to its high theoretical capacity, great cost-effectiveness, good safety, and environmental friendliness. However, due to the fact that in the orthorhombic crystal system of lithium iron phosphate with the Pnma space group, PO<sub>4</sub><sup>3−</sup> leads to the segregation of FeO<sub>6</sub>, which reduces the electronic conductivity and the rate of ionic diffusion along the <italic>b</italic>-axis, resulting in poor rate performance of pure LiFePO<sub>4</sub>. The utilization of crystallographic engineering to regulate the crystal size and morphology of LiFePO<sub>4</sub> has greatly improved its electrical conductivity, enhanced its practical capacity, multiple performance and cycling stability, and realized the large-scale application of lithium iron phosphate in commerce. The common synthesis methods can be divided into liquid-phase and solid-phase methods. The solid-phase method has the advantage of a simple production process, making it easy to achieve large-scale production. Meanwhile, liquid-phase methods can prepare nanoparticles with a narrow range of particle size distributions and controllable morphology, along with lower energy consumption. Additionally, the electrochemical properties of the cathode materials can be effectively improved through the modification of LiFePO<sub>4</sub> nanoparticles. The structural composite of LiFePO<sub>4</sub> with conductive materials enables be