Study on Highly Compacted LiFePO₄ / C Cathode Materials for High-performance 18650 Li-ion Batteries

摘要

The porous spherical LiFePO4 (LFP) nanostructures were synthesized by a spray drying technology,followed by a calcination process. Effect of compacted density on the electrochemical performance ofthe 18650 cells, which employed as-prepared spherical LFP materials, was investigated systemically.The morphology study and physical characterization results show that the spherical LFP/C arecomposed of numerous particles with an average size of 300 nm, and have well-developedinterconnected pore structure and a specific surface area of 12-15 m2/g. For CR2032 coin-type cell, thespecific discharge capacity of the LFP/C was 162-164 mAh/g at 0.2C, and the capacity retention canreach up to 100% after 50 cycles at 1 C. For 18650 batteries, the cathode slurry viscosity of the LFP/Cwith LiOH as lithium source is larger than that with Li2CO3 as lithium source. For the sinteringtemperature of the LFP material is reduced to 700 oC, meanwhile the carbon content is reduced to1.1%, the compacted density of the LFP material electrode can reach 2.47 g/cm3.