Preparation of LiFePO4/C via high-temperature ball-milling route and Box-Behnken design-based optimization

Abstract

LiFePO4/C cathode material was prepared via high-temperature ball-milling route with ultrasonic dispersion as mixing process using eutectic molten salt (0.76 LiOH·H2O-0.24 Li2CO3) as lithium source. Box-Behnken design was used to study the combined effects of ultrasonic time, ball-milling temperature, and ball-milling time on the discharge capacity to obtain the optimum predicted conditions. The optimum conditions were as follows: ultrasonic time was 63 min, ball-milling temperature was 638 °C, and ball-milling time was 7 h. LiFePO4/C prepared from the optimized experimental conditions exhibited a well electrochemical performance; its discharge capacity was 161.3 mAh g−1 at a 0.1 C-rate which was in consistence with the predicted discharge capacity of 160.2 mAh g−1. Moreover, its capacity retention rate achieved 93.6% at a 10 C-rate over 100 cycles.