Zhou Hang-Yu, Sui Zhu-Yin, Amin Kamran, Lin Liang-Wen, Wang Hai-Yan, Han Bao-Hang
CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China.
Key Laboratory of Applied Chemistry of Hebei Province, College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004, China.
ACS Appl Mater Interfaces. 2020 Mar 25;12(12):13904-13913. doi: 10.1021/acsami.9b23006. Epub 2020 Mar 10.
Despite the fact that lithium-sulfur batteries are regarded as promising next-generation rechargeable battery systems owning to high theoretical specific capacity (1675 mA h g) and energy density (2600 W h kg), several issues such as poor electrical conductivity, sluggish redox kinetics, and severe "shuttle effect" in electrodes still hinder their practical application. MXenes, novel two-dimensional materials with high conductivity, regulable interlayer spacing, and abundant functional groups, are widely applied in energy storage and conversion fields. In this work, a TiC/carbon hybrid with expanded interlayer spacing is synthesized by one-step heat treatment in molten potassium hydroxide. The subsequent experiments indicate that the as-prepared TiC/carbon hybrid can effectively regulate polysulfide redox conversion and has strong chemisorption interaction to polysulfides. Consequently, the TiC/carbon-based sulfur cathode boosts the performance in working lithium-sulfur batteries, in terms of an ultrahigh initial discharge capacity (1668 mA h g at 0.1 C), an excellent rate performance (520 mA h g at 5 C), and an outstanding capacity retention of 530 mA h g after 500 cycles at 1 C with a low capacity fade rate of 0.05% per cycle and stable Coulombic efficiency (nearly 99%). The above results indicate that this composite with high catalytic activity is a potential host material for further high-performance lithium-sulfur batteries.
尽管锂硫电池由于其高理论比容量（1675 mA h g）和能量密度（2600 W h kg）而被视为有前景的下一代可充电电池系统，但电极中诸如电导率差、氧化还原动力学迟缓以及严重的“穿梭效应”等几个问题仍然阻碍着它们的实际应用。MXenes是具有高导电性、可调节层间距和丰富官能团的新型二维材料，被广泛应用于能量存储和转换领域。在这项工作中，通过在熔融氢氧化钾中一步热处理合成了层间距扩大的TiC/碳复合材料。随后的实验表明，所制备的TiC/碳复合材料可以有效地调节多硫化物的氧化还原转化，并且对多硫化物具有强烈的化学吸附相互作用。因此，基于TiC/碳的硫正极在工作的锂硫电池中提升了性能，在0.1 C时具有超高的初始放电容量（1668 mA h g）、优异的倍率性能（5 C时为520 mA h g）以及在1 C下500次循环后530 mA h g的出色容量保持率，容量衰减率低至每循环0.05%，库仑效率稳定（接近99%）。上述结果表明，这种具有高催化活性的复合材料是用于进一步高性能锂硫电池的潜在主体材料。
