He Cheng, Liang Yu, Zhang Wenxue
State Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
School of Materials Science and Engineering, Chang'an University, Xi'an 710064, China.
ACS Appl Mater Interfaces. 2022 Jun 29;14(25):29120-29130. doi: 10.1021/acsami.2c07285. Epub 2022 Jun 15.
Lithium-sulfur (Li-S) batteries are highly expected because of their high theoretical specific capacity and energy density. However, its application still faces challenges, including the shuttle effect affecting the sulfur reduction reaction, the high decomposition energy barrier of LiS during charging, the volume change of sulfur, and the poor conductivity during charging and discharging. Here, combined with density functional theory and particle swarm optimization algorithm for the nitrogen carbide monolayer structural search (CN, = 1-8), the surprising discovery is that a single metal-atom-doped CN monolayer could effectively accelerate the conversion of lithium polysulfide and anchor lithium polysulfide during discharging and decrease the decomposition energy barrier of LiS during charging. This "anchoring and catalyzing" mechanism effectively reduces the shuttle effect and greatly improves the reaction kinetics. Among a series of metal atoms, Cr is the best doping element, and it exhibits suitable adsorption energy for polysulfides and the lowest decomposition energy barrier for LiS. This work opens up a new way for the development of transition-metal-doped carbon-nitrogen materials with an excellent catalytic activity for lithium polysulfide as cathode materials for Li-S batteries.
锂硫（Li-S）电池因其高理论比容量和能量密度而备受期待。然而，其应用仍面临挑战，包括影响硫还原反应的穿梭效应、充电过程中LiS的高分解能垒、硫的体积变化以及充放电过程中的低导电性。在此，结合密度泛函理论和用于碳化氮单层结构搜索的粒子群优化算法（CN，n = 1-8），令人惊讶地发现，单个金属原子掺杂的CN单层在放电过程中可有效加速多硫化锂的转化并锚定多硫化锂，同时在充电过程中降低LiS的分解能垒。这种“锚定和催化”机制有效降低了穿梭效应并极大地改善了反应动力学。在一系列金属原子中，Cr是最佳掺杂元素，它对多硫化物表现出合适的吸附能且对LiS具有最低的分解能垒。这项工作为开发具有优异催化活性的过渡金属掺杂碳氮材料作为锂硫电池的阴极材料开辟了一条新途径。
