Sandwich-Like C@SnS@TiO<sub>2</sub> Anodes with High Power and Long Cycle for Li-Ion Storage
Lini Zhao, Guorong Chen, Tingting Yan, Jianping Zhang, Liyi Shi, Dengsong Zhang
Abstract
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 [email protected]@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 [email protected]@TiO2 is basically reversible in the following charging/discharging processes. As a result, the sandwich-like [email protected]@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.