Mahankali Kiran, Gottumukkala Sundeep Varma, Masurkar Nirul, Thangavel Naresh Kumar, Jayan Rahul, Sawas Abdulrazzag, Nagarajan Sudhan, Islam Md Mahbubul, Arava Leela Mohana Reddy
Department of Mechanical Engineering, Wayne State University, 5050 Anthony Wayne Drive, Detroit, Michigan 48202, United States.
Department of Electrical and Computer Engineering, Wayne State University, 5050 Anthony Wayne Drive, Detroit, Michigan 48202, United States.
ACS Appl Mater Interfaces. 2022 Jun 1;14(21):24486-24496. doi: 10.1021/acsami.2c05508. Epub 2022 May 18.
The dissolution of intermediate lithium polysulfides (LiPS) into an electrolyte and their shuttling between the electrodes have been the primary bottlenecks for the commercialization of high-energy density lithium-sulfur (Li-S) batteries. While several two-dimensional (2D) materials have been deployed in recent years to mitigate these issues, their activity is strictly restricted to their edge-plane-based active sites. Herein, for the first time, we have explored a phase transformation phenomenon in a 2D material to enhance the number of active sites and electrocatalytic activity toward LiPS redox reactions. Detailed theoretical calculations demonstrate that phase transformation from the 2H to 1T' phase in a MoSe material activates the basal planes that allow for LiPS adsorption. The corresponding transformation mechanism and LiPS adsorption capabilities of the as-formed 1T'-MoSe were elucidated experimentally using microscopic and spectroscopic techniques. Further, the electrochemical evaluation of phase-transformed MoSe revealed its strong electrocatalytic activity toward LiPS reduction and their oxidation reactions. The 1T'-MoSe-based cathode hosts for sulfur later provide a superior cycling performance of over 250 cycles with a capacity loss of only 0.15% per cycle along with an excellent Coulombic efficiency of 99.6%.
中间态多硫化锂（LiPS）溶解到电解质中以及它们在电极之间穿梭，一直是高能量密度锂硫（Li-S）电池商业化的主要瓶颈。尽管近年来已采用几种二维（2D）材料来缓解这些问题，但其活性严格限于基于边缘平面的活性位点。在此，我们首次探索了二维材料中的相变现象，以增加活性位点数量并提高对LiPS氧化还原反应的电催化活性。详细的理论计算表明，MoSe材料中从2H相向1T'相的相变激活了允许LiPS吸附的基面。使用显微镜和光谱技术通过实验阐明了所形成的1T'-MoSe的相应转变机制和LiPS吸附能力。此外，对相变后的MoSe的电化学评估揭示了其对LiPS还原及其氧化反应具有很强的电催化活性。基于1T'-MoSe的硫正极主体随后提供了超过250次循环的优异循环性能，每次循环的容量损失仅为0.15%，同时具有99.6%的出色库仑效率。
