Co9S8/Biocarbon Tubular Nanocomposite with Low-Temperature Performance for Lithium Storage

Transition-metal sulfides as anodes for lithium-ion batteries (LIBs) have attracted more attention due to their good conductivity and high capacity. However, relevant lithium storage at low temperatures has been less reported so far. Herein, willow catkins (WC) as biotemplate were simply soaked in cobalt salt solution, and the obtained precursors were in situ carbonized, calcined, and sulfurated under different atmospheres to generate two biomorphic Co9S8-based tubes. The biomass-derived carbon (BC) decorated Co9S8 nanocomposite (Co9S8/BC) shows that Co9S8 nanoparticles (ave. 30 nm) are homogeneously embedded in biocarbon tubes, which can effectively relieve the volume expansion of Co9S8 nanoparticles. As anode for LIBs, the Co9S8/BC electrode exhibits good rate performance (437 mA h g–1, 5 A g–1) and long-cycling stability (510.3 mA h g–1, 2000 cycles, 1 A g–1) at room temperature. Especially at 0 and −20 °C, the capacities can separately remain at 397.2 and 197.1 mA h g–1 after 150 cycles at 1 A g–1. The excellent electrochemical performance is mainly attributed to the synergistic effect of the unique microstructure and biomass-derived graphitic carbon, which can offer more active sites, enhance the conductivity, and relieve the volume expansion of the electrode material.