Synthesis and electrochemical analysis of Sn2Fe-TiOx-C composite as a high-performance anode material for Li-ion batteries

Tin-based intermetallic compounds are regarded as a promising alternative for Li secondary battery anodes due to their high specific and volumetric capacity, as well as their low operating potential. However, the materials' cycling performance still cannot meet the required standards for commercialization. In this study, we designed and synthesized a Sn2Fe-TiOx-C composite as a high-capacity anode material via high-energy mechanical milling and hydrogen treatment. The synthesized material was characterized by several analytical tools. The reaction mechanism of the composite electrode with Li was investigated with ex situ X-ray diffraction analysis, and the conversion of Sn2Fe to Li-Sn alloy and Fe during Li insertion and its reversibility were confirmed. The results of an electrochemical test showed that a reversible capacity of 651 mAh g-1 was retained after 100 cycles. This cycling stability could be attributed to the microstructure in which Sn2Fe was uniformly distributed in the TiOx and carbon matrix. Additionally, there was an improvement in rate performance after hydrogen treatment because titanium oxide produced during mechanical milling was partially reduced, which was helpful for enhancing the electrical conductivity of the composite electrode.