TiO2 as a multifunction coating layer to enhance the electrochemical performance of SiOx@TiO2@C composite as anode material

SiOx-based anode materials suffer from inherent defects of volume expansion, high initial capacity loss, and the huge electron and ion resistance in the unstable solid electrolyte interphase layer impede their commercialization. Surface coating is the most prevalent strategy for resolving the key concerns. In this paper, we present a dual-shell coating structural composite (denoted as SiOx@TiO2@C) through a two-step process. By introducing a high-quality anatase-phase TiO2 layer, a highly stable interface and decreased resistance to electron and ion diffusion of composite are achieved and investigated systematically. Additionally, the side reactivity is studied firstly. Moreover, the enhanced safety of the electrode is evaluated. The as-prepared composite exhibites a high initial discharge capacity of 1624.7 mAh g−1 with an initial coulombic efficiency (ICE) of 81.2%, capacity retention of 89.5% (vs 2nd discharge) after 800 cycles, and a reversible capacity of 949.7 mAh g−1 at 10 A g−1. The assembled full-cell exhibites an initial area capacity of 2.6 mAh cm−2 with an ICE higher than 90%; the exceeding 106 times and 60 times increase in electron conductivity and Li+ conductivity facilitate electron and ion diffusion particularly at high rates. The approximately 1.5 times higher energy barrier implies the blocking effect of the TiO2 layer on the side reaction. The almost 4 times decrease in the accumulated enthalpy reveals the positive effect of the anatase-phase TiO2 layer on thermal stability. The probable reasons associated with the interface stability are discussed and proposed in this paper.