Facile synthesis of C, N, P co-doped SiOx as anode material for lithium-ion batteries with excellent rate performance

Abstract

SiOx has high specific capacity for lithium-ion batteries, but the rate and the cycling performances need to be further improved to satisfy the needs of the future. In this study, the C, N, P doping SiOx/G@CNP anodes are prepared by a facile ball milling and heat treatment process. The electrochemical performances of SiOx are improved by the synergistic effect of C, N, P doping. The SiOx/G@CNP-2 anode with the addition of 20 wt% phytate shows the best electrochemical performances and maintains a specific capacity of 77.45% after 150 cycles at 0.2 A·g−1. Importantly, it exhibits a remarkable rate performance with specific capacities of 528.2 mAh·g−1 and 370.0 mAh·g−1 even at 3.0 and 5.0 A·g−1, respectively. Artificial graphite and the carbon shell formed by the thermal decomposition of citric acid contribute to the structural stability of SiOx and improve the cycling performance of the material. Moreover, the addition of P element and high content of pyridine N accelerates the rate of Li+ deintercalation, and the conductivity and ion diffusion coefficient of the material are effectively promoted, thus greatly improving the rate performance of the material. This work presented herein provides a simple and feasible method for the preparation of high-performance anode materials.