Huang Zhen-Dong, Fang Yanwu, Yang Mingtong, Yang Jike, Wang Yizhou, Wu Zhen, Du Qingchuan, Masese Titus, Liu Ruiqing, Yang Xusheng, Qian Chenhui, Jin Shaowei, Ma Yanwen
Key Laboratory for Organic Electronics and Information Displays & Jiangsu Key Laboratory for Biosensors, Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM) , Nanjing University of Posts and Telecommunications , 9 Wenyuan Road , Nanjing 210023 , P. R. China.
Shaanxi Key Laboratory of Energy Chemical Process Intensification, School of Chemical Engineering and Technology , Xi'an Jiaotong University , Xi'an 710049 , P. R. China.
ACS Appl Mater Interfaces. 2019 Jun 5;11(22):20013-20021. doi: 10.1021/acsami.9b04246. Epub 2019 May 22.
To enhance the utilization of sulfur in lithium-sulfur batteries, three-dimensional tungsten nitride (WN) mesoporous foam blocks are designed to spatially localize the soluble LiS and LiS within the pore spaces. Meanwhile, the chemisorption behaviors of polysulfides and the capability of WN as an effective confiner are systematically investigated through density functional theory calculations and experimental studies. The theoretical calculations reveal a decrease in chemisorption strength between WN and the soluble polysulfides (LiS > LiS > LiS), while the interactions between WN and the insoluble LiS/LiS show a high chemisorption strength of ca. 3 eV. Validating theoretical insights through electrochemical measurements further manifest that the assembled battery configurations with sulfur cathode confined in the thickest WN blocks exhibit the best rate capabilities (1090 and 510 mAh g at 0.5C and 5C, respectively) with the highest initial Coulombic efficiency of 90.5%. Moreover, a reversible capacity of 358 mAh g is maintained with a high Coulombic efficiency approaching to 100%, even after 500 cycles at 2C. As guided by in silico design, this work not only provides an effective strategy to improve the retentivity of polysulfides but also underpins that properly architectured WN can be effective retainers of polysulfides.
为提高锂硫电池中硫的利用率，设计了三维氮化钨（WN）介孔泡沫块，以便在孔隙空间内对可溶性LiS和LiS进行空间定位。同时，通过密度泛函理论计算和实验研究，系统地研究了多硫化物的化学吸附行为以及WN作为有效限制剂的能力。理论计算表明，WN与可溶性多硫化物（LiS > LiS > LiS）之间的化学吸附强度降低，而WN与不溶性LiS/LiS之间的相互作用显示出约3 eV的高化学吸附强度。通过电化学测量验证理论见解进一步表明，硫阴极限制在最厚WN块中的组装电池配置表现出最佳的倍率性能（在0.5C和5C时分别为1090和510 mAh g），初始库仑效率最高可达90.5%。此外，即使在2C下循环500次后，仍保持358 mAh g的可逆容量，库仑效率接近100%。在计算机辅助设计的指导下，这项工作不仅提供了一种提高多硫化物保留率的有效策略，而且还证明了结构合理的WN可以成为多硫化物的有效保留剂。
