Synthesis and performance of Ti2O3/LiTiO2 decorated micro-scale Si-based composite anode materials for Li-ion batteries†

The performance of commercially available alloy-based Si anodes is hindered by rapid capacity degradation caused by volume expansion and poor rate performance stemming from their semiconductor properties. To address these challenges, we propose a Si surface modification layer for stress-relieving coupled with enhancing electrical conductivity through multiphase composite design. We prepare a scalable micro- and nano-multiphase composite Si-based anode by wet milling low-cost micro-Si and employing a heat treatment process. In this design, a SiO_x layer was introduced on the Si surface by wet milling using a pitch–ethanol solution. The pitch, tetra-n-butyl titanate (TBOT) and LiOH as a precursor were introduced to obtain Ti₂O₃ and LiTiO₂. Combined with graphite to inhibit the internal micro-Si expansion and enhance the ionic transport capacity, the synthesized Si-based composites have an initial coulombic efficiency (ICE) of up to 82% and a high rate performance when used as an anode. Remarkably, the synthesized composite structure with the optimized Ti-source maintains a commendable capacity retention of 51.3% over 400 cycles, with a negligible capacity loss of 0.12% per cycle. This equates to a capacity of 396.7 mA h g⁻¹, which surpasses the theoretical specific capacity of current commercial graphite anodes. These findings underscore the significant improvement in Li-ion diffusion and electrochemical performance achieved by introducing multiphase composite structures into micro-Si materials. Moreover, the straightforward preparation process demonstrates considerable potential for industrial production.