Razaq Rameez, Sun Dan, Xin Ying, Li Qian, Huang Taizhong, Zheng Lei, Zhang Zhaoliang, Huang Yunhui
School of Chemistry and Chemical Engineering, Shandong Provincial Key Laboratory of Fluorine Chemistry and Chemical Materials, University of Jinan, Jinan 250022, People's Republic of China.
Nanotechnology. 2018 Jul 20;29(29):295401. doi: 10.1088/1361-6528/aac060. Epub 2018 Apr 26.
Among different energy storage devices, the lithium-sulfur (Li-S) battery is the subject of recent attention. However, the capacity decay caused by polysulfide shuttle leading to sluggish kinetics of polysulfide redox reactions is the main hindrance for its practical application in Li-S batteries. Herein, molybdenum carbide nanoparticles anchored on carbon nanotubes (MoC/CNT) are reported to serve as an efficient cathode material to enhance the electrochemical kinetics of polysulfide conversion in Li-S batteries. MoC/CNT shows strong adsorption and activation of polar polysulfides and therefore accelerates the redox kinetics of polysulfides, reduces the energy barrier, effectively mitigates the polarization and polysulfide shuttle, thus improving the electrochemical performance. The S-MoC/CNT composite with 70 wt% sulfur loading exhibits high specific discharge capacity (1206 mA h g at 0.5 C), excellent high-rate performance, long cycle life (900 cycles), and outstanding Coulombic efficiency (∼100%) at a high rate (2 C) corresponding to a capacity decay of only 0.05%. Remarkably, the S-MoC/CNT cathode with high areal sulfur loading of 2.5 mg cm exhibits high-rate capacities and stable cycling performance over 100 cycles, offering the potential for use in high energy Li-S batteries.
在不同的储能装置中，锂硫（Li-S）电池是近期备受关注的对象。然而，多硫化物穿梭导致的容量衰减致使多硫化物氧化还原反应动力学迟缓，这是其在锂硫电池实际应用中的主要障碍。在此，据报道，锚定在碳纳米管上的碳化钼纳米颗粒（MoC/CNT）可作为一种高效的阴极材料，以增强锂硫电池中多硫化物转化的电化学动力学。MoC/CNT对极性多硫化物表现出强烈的吸附和活化作用，因此加速了多硫化物的氧化还原动力学，降低了能垒，有效减轻了极化和多硫化物穿梭现象，从而提高了电化学性能。硫负载量为70 wt%的S-MoC/CNT复合材料在0.5 C下表现出高比放电容量（1206 mA h g）、优异的高倍率性能、长循环寿命（900次循环）以及在2 C高倍率下出色的库仑效率（约100%），对应的容量衰减仅为0.05%。值得注意的是，面硫负载量为2.5 mg cm的S-MoC/CNT阴极在100次循环中表现出高倍率容量和稳定的循环性能，为其在高能锂硫电池中的应用提供了潜力。
