(704c) A General Approach to Synthesize Free-Standing Metal Selenides@ Carbon Nanofibers Anode for Lithium/Sodium Ion Batteries

The trend of developing lighter, smaller, long-lasting portable devices has driven researchers to explore the next generation materials for lithium ion batteries (LIBs) and beyond including sodium ion batteries (SIBs). Transition metal selenides are a notable group that could not only theoretically provide higher specific capacities than commercial graphite anode through conversion reaction, but also show good conductivity, stability, as well as cost-effectiveness. Herein, we report a general approach to develop free-standing metal selenides/carbon nanofibers (CNFs) composites as the anode for LIBs/SIBs via electrospinning. The structure-property-performance relationship of the composites of different metal selenides (MSe, M=Sn, Fe, Ni, Cu) anchored on the CNFs was thoroughly investigated in LIBs system. The potential application in SIBs was also explored. The free-standing composites anodes via the facile one-step preparation showed high specific capacity, good rate capability, and long-term stability. Their good performance can be ascribed to the following reasons: i) the unique structure provided by the electrospinning can alleviate the volume change during the repeated charge/discharge; ii) the good conductivity given by the integration of carbon nanofiber and active metal selenides materials could promote fast electron transfer; iii) the absence of the binder, extra conductive materials, and current collector not only reduces the weight of the anode, but also eliminate the uncontrollable structures caused by slurry making. When extended the application to SIBs, the composites demonstrated great potentials. The postmortem analysis further confirmed the robust structure stability of the rationally designed composites. In conclusion, the free-standing metal selenides and carbon nanofibers composites are very promising electrode materials for next-generation flexible and lightweight batteries that are crucial for various emerging applications such as wearable electronics.