Phytic acid-derived Co2P/N-doped carbon nanofibers as flexible free-standing anode for high performance lithium/sodium ion batteries.

Transition metal phosphides (TMPs) have been regarded as promising substitutes for lithium/sodium storage mainly due to the high capacity and good security. However, great challenges have to face in ultimate application, especially the problem of active substances uneven mixing in the electrode preparation process and structural collapse during circulation. Herein, we report a novel and facile strategy for synthesis 3D flexible conductive network hybrids of PA-derived Co 2 P nanoparticles encapsulated into N-doped carbon skeleton (Co 2 P/NC). The as-prepared Co 2 P/NC nanofibers acting as freestanding binder-free anode material can provide highly dispersed Co 2 P nanoparticles in cross-linked frameworks and effectively alleviate the structural collapse, bring about superior rate performance during repeated cycles. When applied in lithium-ion battery, the Co 2 P/NC nanofibers exhibit high capacity (1041.5 mA h g−1 after 200 cycles at 100 mA g−1), excellent rate performance and long lifespan (retain a steady reversible capacity of 563.6 mA h g−1 with CE ∼100% after 1000 cycles at 10 A g−1). As for sodium-ion batteries, it also exhibits long-term stability and better reversible capacity (retains 132.3 mA h g−1 after 2500 cycles at 1.0 A g−1). The SEM results show that the morphology of Co 2 P/NC after 1000th lithium (10 A g−1)/sodium (1.0 A g−1) storage circulation can still maintain good integrity. Image 1 • Highly dispersed Co 2 P nanoparticles wrapping by N-doped carbon conductive support effectively restrain volume expansion. • Co 2 P/NC nanofibers can be directly acted as freestanding binder-free electrode with superior flexibility and conductivity. • The as-prepared Co 2 P/NC exhibit excellent high-rate performance and superior cycling stability in LIBs and SIBs. • For LIBs, a steady reversible capacity of 563.6 mA h g-1 can be obtained after 1000 cycles at 10 A g-1. • For SIBs, a steady reversible capacity of 132.3 mA h g-1 can be obtained after 2500 cycles at 1.0 A g-1. [ABSTRACT FROM AUTHOR]