Particle Size Grading Strategy for Enhanced Performance of Lithium Iron Phosphate Cathode Materials

Lithium iron phosphate (LiFePO4) is a promising cathode material for lithium-ion batteries (LIBs), but its low conductivity and poor rate performance limit its application in high-power devices. In this study, we employed a particle size grading strategy to enhance the electrochemical performance of LiFePO4. By mixing small and large particles in different ratios (3:1, 2:1, 1:1, 1:2, and 1:3), we synthesized graded iron phosphate precursors, which were then used to prepare LiFePO4 cathode materials. The effects of particle size distribution on the material’s structural properties and electrochemical performance were systematically investigated. SEM images revealed that the morphology of LiFePO4 changed with varying precursor ratios, with the 3:1 ratio resulting in a more uniform particle distribution. The results showed that the 3:1 ratio exhibited the highest discharge capacity of 159.4 mAh/g, while larger particle ratios (2:1 and 1:1) led to decreased capacity due to the increased proportion of larger particles. Additionally, the LiFePO4 materials prepared from non-in situ mixed precursors exhibited higher tap densities, with the 2:1 ratio achieving the highest tap density of 2.545 g/cm3. This study demonstrates the effectiveness of the particle size grading approach in improving the electrochemical properties of LiFePO4 and provides insights into the design of high-performance cathode materials for advanced lithium-ion batteries.