Si/TiO2/Ti2O3 composite carbon nanofiber by one-step heat treatment with highly enhanced ion/electron diffusion rates for next-generation lithium-ion batteries

摘要

Silicon anodes are one of the most promising candidate materials for next-generation lithium-ion batteries because of their high theoretical capacity and natural abundance. Unfortunately, the poor conductivity of silicon and large volume expansion (>400%) during the cycle restrict its commercialization. Herein, we combine Si with stable TiO2 and electrically conductive Ti2O3 to significantly increase the capacity and cycle stability of the Si-based anodes. The preparation of a Si/TiO2/Ti2O3-Carbon Nanofiber (denoted as STTC) composite via mechanical blending, electrospinning and subsequent carbonization of Si, TiO2, and polyacrylonitrile (PAN). This material exhibits a reversible specific capacity of 924 mAh g(-1) after 500 cycles of 1 A g(-1) current density. Moreover, it also exhibits excellent rate performance even at current densities of 6 A g(-1). The outstanding electrochemical performance can be ascribed to Ti2O3 generates in the carbonization process has high ion diffusivity and electrical conductivity. Furthermore, the disordered frame of TiO2/Ti2O3 forms voids, which can alleviate the volume expansion of silicon, maintain the electrode integrity during charge and discharge, and form a thin and stable solid electrolyte interphase (SEI). Additionally, the conductive frame of carbon nanofibers also significantly improves the ion and electron conductivity of the complete electrode. (C) 2020 Elsevier Ltd. All rights reserved.