Sandwich-Like C@SnS@TiO₂ Anodes with High Power and Long Cycle for Li-Ion Storage

Up to now, high energy density batteries can be easily achieved by using alloys or conversion materials with high theoretical capacities (such as silicon-based and tin-based materials). However, these anode materials tend to sacrifice power densities while maintaining high energy densities. Herein, a sandwich-like C@SnS@TiO₂ anode with both high capacity and high power is designed by controlling a close integration between interfacial layers. The volume expansion of the middle layer of the SnS in the C@SnS@TiO₂ anode is greatly constrained by a synergetic interaction of the TiO₂ core and the carbon shell. From the results of the real-time dynamic evolution of electrode thickness during charging and discharging processes, the sandwich-like C@0.5SnS@TiO₂ has a max expansion rate of 11.5% in the first lithiation, which is much lower than that of pristine SnS (89.2%), and the expansion of C@0.5SnS@TiO₂ is basically reversible in the following charging/discharging processes. As a result, the sandwich-like C@0.5SnS@TiO₂ anode delivers a stable capacity of 660mAh g^-1 at 50 mA g^-1 and manifests an excellent rate capability, with a capacity of 357.2 mAh g^-1 at 5A g^-1 and a recovery ability of nearly 100%. In addition, it exhibits an outstanding long lifespan, retaining 95.6% capacity after 2500 cycles at 1A g^-1. This work presents a durable tin-based anode with moderate capacity for high-energy batteries and offers some ideas for the delicate study of materials with severe expansion during circulation.