Construction of carbon confined CoP@carbon nanotube hybrid networks assisted by phytic acid toward high-performance lithium-ion batteries

The transition metal phosphides (TMPs) as alternative anode materials have considerable potential for lithiumion batteries (LIBs) due to their high theoretical capacity. However, the poor-rate capability and capacity degradation arisen from low electrical conductivity and structural change are still great challenging bottlenecks for TMPs-based anodes. Here, we synthesize the carbon-terminated CoP@carbon nanotube (CoP@CNT) composites by the thermal decomposition of phytic acid (PA) cross-linked cobalt complexes intertwined with carbon nanotubes (CNTs). Compared to other phosphorization processes, the PA-assisted approach is more green, safe, and suitable for mass production. More importantly, the PA can also be served as carbon source to direct realization of in-situ carbon-coating during the sintering process. When used the CoP@CNT as an anode for LIBs, the CNT skeleton can provide high-speed pathways for electron/ion transport; meanwhile, the carbon layer physically restricts the CoP to alleviate volume change effectively. Benefiting from these merits, the CoP@CNT electrodes exhibit an average lithium storage capacity of 1159 mA h g(-1) at 0.2 A g(-1), excellent rate capability (425 mA h g(-1) at 10 A g(-1)), and cyclic stability (524 mA h g(-1) after 900 cycles at 2 A g(-1)).