Achieving a high-performance P/C anode through P-O-C bond for sodium ion batteries

Abstract

Red phosphorus is a potentially attractive anode for sodium ion batteries because of its ultrahigh theoretical capacity. However, its poor cycling performance caused by the large volume expansion during Na ions insertion and extraction process hinders the practical application of red P. Herein, P/C composites have been prepared through a simple and one-step high energy mechanical milling process using low-cost anthracite as carbon sources. The adding of metal oxides (TiO2 and MoO2) during the high energy mechanical milling process introduces the oxygen element. The bonding strength of P/C composites has been enhanced through the formation of P-O-C chemical bond on the interface between P and C, resulting in the improved cycling stability and rate capability. As anodes for sodium ion batteries, P-TiO2-C and P-MoO2-C electrodes exhibit high reversible capacities of 843 and 920 mAh g−1 over 60 cycles at 0.1 A g−1, respectively. At 0.5 A g−1, P-TiO2-C and P-MoO2-C electrodes also display superior reversible capacities of 640 mAh g−1 after 100 cycles and 720 mAh g−1 after 120 cycles for sodium ion batteries. This result indicates that the addition of metal oxides significantly improves the electrochemical performance of P/C composite.