School of Physics and Electronics, Hunan Key Laboratory of Super Microstructure and Ultrafast Process, Hunan Key Laboratory of Nanophotonics and Devices, State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China.
Phys Chem Chem Phys. 2023 Jun 28;25(25):16968-16978. doi: 10.1039/d3cp00371j.
Developing highly active single-atom catalysts (SACs) for suppressing the shuttle effect and enhancing the kinetics of polysulfide conversion is regarded as an important approach to improve the performance of Li-S batteries. However, the adsorption behaviors of polysulfides and the catalytic properties of host materials remain obscure due to the lack of mechanistic understanding of the structure-performance relationship. Here, we identify that the adsorption energies of polysulfides on 3d transition-metal atoms supported by two-dimensional α-InSe with downward polarization (TM@InSe) are highly correlated with the d-band centers of the TM atoms. Introduction of the TM atoms on the α-InSe surface improves the electrical conductivity and meanwhile, significantly enhances the adsorption strength of polysulfides and suppresses the shuttle effect. A mechanistic study of polysulfide conversion on TM@InSe shows that the LiS dissociation is the potential-determining step with low activation energies, indicating that TM@InSe can accelerate the kinetics of polysulfide conversion. Electronic structure analysis shows that the kinetics of the potential-determining step on TM@InSe is related to the TM-S interaction in LiS-adsorbed TM@InSe. A linear scaling relationship between activation energy and the integrated crystal orbital Hamilton population of TM-S in the potential-determining step on TM@InSe is identified. Based on the evaluation of stability, conductivity and activity, we concluded that Ti@InSe, V@InSe, and Fe@InSe are the promising cathode materials for Li-S batteries. Our findings provide a fundamental understanding of the intrinsic link between the electronic structure and catalytic activity for polysulfide conversion and pave a way for the rational design of SAC-based cathodes for Li-S batteries.
开发高效的单原子催化剂（SACs）以抑制穿梭效应并增强多硫化物转化的动力学，被认为是提高锂硫电池性能的重要途径。然而，由于缺乏对结构-性能关系的机械理解，多硫化物的吸附行为和主体材料的催化性能仍然不清楚。在这里，我们确定二维α-InSe 支撑的 3d 过渡金属原子（TM@InSe）上多硫化物的吸附能与 TM 原子的 d 带中心高度相关。在α-InSe 表面引入 TM 原子提高了电导率，同时显著增强了多硫化物的吸附强度并抑制了穿梭效应。对 TM@InSe 上多硫化物转化的机理研究表明，LiS 离解是具有低活化能的势控步骤，表明 TM@InSe 可以加速多硫化物转化的动力学。电子结构分析表明，TM@InSe 上势控步骤的动力学与 LiS 吸附在 TM@InSe 上的 TM-S 相互作用有关。在 TM@InSe 上势控步骤中，活化能和 TM-S 的积分晶体轨道哈密顿人口之间存在线性标度关系。基于稳定性、电导率和活性的评估，我们得出 Ti@InSe、V@InSe 和 Fe@InSe 是有前途的锂硫电池阴极材料。我们的发现为多硫化物转化的电子结构和催化活性之间的内在联系提供了基本的理解，并为基于 SAC 的锂硫电池阴极的合理设计铺平了道路。
