Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, N2L 3G1 (Canada).
Angew Chem Int Ed Engl. 2015 Mar 23;54(13):3907-11. doi: 10.1002/anie.201410174. Epub 2015 Feb 3.
Lithium-sulfur batteries are amongst the most promising candidates to satisfy emerging energy-storage demands. Suppression of the polysulfide shuttle while maintaining high sulfur content is the main challenge that faces their practical development. Here, we report that 2D early-transition-metal carbide conductive MXene phases-reported to be impressive supercapacitor materials-also perform as excellent sulfur battery hosts owing to their inherently high underlying metallic conductivity and self-functionalized surfaces. We show that 70 wt % S/Ti2 C composites exhibit stable long-term cycling performance because of strong interaction of the polysulfide species with the surface Ti atoms, demonstrated by X-ray photoelectron spectroscopy studies. The cathodes show excellent cycling performance with specific capacity close to 1200 mA h g(-1) at a five-hour charge/discharge (C/5) current rate. Capacity retention of 80 % is achieved over 400 cycles at a two-hour charge/discharge (C/2) current rate.
锂硫电池是最有前途的候选者之一，可以满足新兴的储能需求。抑制多硫化物穿梭，同时保持高硫含量，是其实际发展面临的主要挑战。在这里，我们报告说，二维早期过渡金属碳化物导电 MXene 相——被报道为令人印象深刻的超级电容器材料——也表现出优异的硫电池宿主，因为它们具有固有的高基础金属导电性和自功能化表面。我们表明，由于多硫化物物种与表面 Ti 原子的强相互作用，70wt% S/Ti2 C 复合材料表现出稳定的长期循环性能，这一点通过 X 射线光电子能谱研究得到了证明。在 5 小时的充放电（C/5）电流速率下，正极的比容量接近 1200 mA h g(-1)，具有优异的循环性能。在 2 小时的充放电（C/2）电流速率下，经过 400 次循环后，容量保持率达到 80%。
