Functionalized porous conductive carbon layer improves the low-temperature performance of LiFePO4 cathode material for lithium-ion batteries

Lithium iron phosphate (LiFePO4) has been successfully utilized due to its stable structure, low cost, and higher safety. Nevertheless, the sluggish diffusion kinetics and low electrical conductivity have suppressed the rate capacity and long-term cyclability at lower temperature, causing significant capacity degradation problems. Herein, to address such issues, a well-designed 3D porous structure LFP@NS is synthesized via the sol-gel method combined with a high-temperature calcination route. Furthermore, the nitrogen and sulfur in thiourea can be induced to enter the carbon matrix, resulting in generating more defects and active sites. Simultaneously, N,S codoped carbon matrix can form successive migration channels for lithium-ion, which can promote the diffusion kinetics and electrical conductivity. The as-prepared LFP@NS-2 sample provides 158.5 mAh g- 1 discharge capacity in the room temperature (RT) and 101.3 mAh g- 1 (in -20 degrees C) at 1C, and exhibits remarkable cyclic performance (122.3 mAh g- 1 after 2000 circles at 10C in the RT). Furthermore, to investigate the practical application in low temperature, coupled with a graphite (Gr) anode, the LFP@NS-2||Gr full battery releases 100.1mAh g- 1 at 1C in -20 degrees C. Therefore, this work has a far-reaching implication for designing the highperformance LIBs electrode materials for practical application at low temperature.