Cowpea-like N-Doped Silicon Oxycarbide/Carbon Nanofibers as Anodes for High-Performance Lithium-Ion Batteries

Silicon oxycarbide (SiOC) is considered as a potential anode material in lithium-ion batteries because of its high theoretical capacity and good structural stability. Despite many such assets, its low electronic conductivity causes poor rate capability and rapid attenuation of capacity. Herein, we report the fabrication of cowpea-like N-doped carbon nanofiber-encapsulated SiOC spheres (SiOC/C NFs) in which the Si–N bridging is introduced into SiOC. Our method not only demonstrates an improved electronic conductivity and a shortened ionic diffusion distance but also prevents agglomeration by avoiding direct contact with the electrolyte. As anode materials for lithium-ion batteries, this SiOC/C NF material delivers a high reversible capacity (707 mA h g–1 at 0.1 A g–1 after 100 cycles), a good rate performance (468 mA h g–1 at 1.6 A g–1), and an excellent cycling stability (570 mA h g–1 at 0.4 A g–1 after 800 cycles). Moreover, the full cell of LiFePO4//SiOC/C NFs exhibits excellent electrochemical properties, which demonstrates its prospect of great potential as an anode material for high-performance lithium-ion batteries.