Zhang Xingxing, Zhang Fang, Su Qingmei, Hou Xuehan, Chen Rui, Chen Zhuo, Du Gaohui, Shi Weihao, Shi Yang, Lv Yujie, Huang Wenhuan, Xu Bingshe
School of Materials Science & Engineering, Shaanxi University of Science and Technology, Xi'an, 710021, P. R. China.
Materials Institute of Atomic and Molecular Science, School of Physics & Information Science, Shaanxi University of Science and Technology, Xi'an, 710021, P. R. China.
Small. 2024 Dec 4:e2407283. doi: 10.1002/smll.202407283.
Since lithium-sulfur (Li-S) batteries have high energy density and environmental friendliness, they have garnered a lot of attention as a new type of energy storage technology. However, the shuttle effect of lithium polysulfides (LiPSs) and low utilization of sulfur (S) in Li-S batteries reduce the cycle stability and energy efficiency and limit their practical application. Therefore, it is urgent to achieve simultaneous immobilization and conversion of LiPSs utilizing catalysts. Herein, a metal-organic framework (MOF)-derived MoC/WC@NC heterojunction is synthesized as a bidirectional catalyst for LiPSs in high-performance Li-S batteries. Experimental and theoretical calculations indicate that the catalyst is expected to improve the catalytic activity for reduction and oxidation reactions of LiPSs, thereby accelerating the kinetics of Li-S batteries. In conclusion, with the incorporation of the novel catalyst between the cathodes and separators in Li-S batteries, the assembled batteries demonstrate excellent rate performance, with an initial discharge capacity of 1752.1 mAh g at 0.1 C, and a discharge-specific capacity of 783.2 mAh g even at 2 C. More significantly, the coulombic efficiency stayed above 99% and the capacity of 589.1 mAh g after 1000 cycles at 1 C with a decay rate of only 0.062% each cycle.
由于锂硫（Li-S）电池具有高能量密度和环境友好性，作为一种新型储能技术受到了广泛关注。然而，锂硫电池中多硫化锂（LiPSs）的穿梭效应以及硫（S）的低利用率降低了循环稳定性和能量效率，限制了它们的实际应用。因此，迫切需要利用催化剂实现LiPSs的同时固定和转化。在此，合成了一种金属有机框架（MOF）衍生的MoC/WC@NC异质结，作为高性能锂硫电池中LiPSs的双向催化剂。实验和理论计算表明，该催化剂有望提高LiPSs还原和氧化反应的催化活性，从而加速锂硫电池的动力学。总之，通过在锂硫电池的阴极和隔膜之间引入这种新型催化剂，组装的电池表现出优异的倍率性能，在0.1 C下初始放电容量为1752.1 mAh g，即使在2 C下放电比容量仍为783.2 mAh g。更显著的是，库仑效率保持在99%以上，在1 C下经过1000次循环后容量为589.1 mAh g，每次循环的衰减率仅为0.062%。
