Ji Yujin, Dong Huilong, Yang Mingye, Hou Tingjun, Li Youyong
Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou, Jiangsu 215123, China.
Phys Chem Chem Phys. 2017 Aug 9;19(31):20457-20462. doi: 10.1039/c7cp04044j.
The development of novel cathode catalysts is of great importance to the practical applications of nonaqueous lithium oxygen (Li-O) batteries. Here by using first-principles calculations, we revealed the catalytic mechanism and evaluated the catalytic activity of monolayer germanium monochalcogenides (2D-GeXs, X = S/Se) as cathode catalytic materials. For 2D-GeXs, LiO with a ring-like structure is the final discharge product. The free energy diagram demonstrates that 2D-GeSe is more energetically favorable than 2D-GeS due to its considerably lower oxygen reduction reaction (ORR) overpotential (0.94 V) and oxygen evolution reaction (OER) overpotential (1.30 V), which originate from its weaker binding with LiO and stronger binding with the inserted Li atom. The analyses on electronic properties elucidate that the final product of LiO on 2D-GeSe induces the semiconductor to semi-metal transition. Our results reflect that 2D-GeSe is an excellent candidate as a cathode material in nonaqueous Li-O batteries, while 2D-GeS is not appropriate.
新型阴极催化剂的开发对于非水锂氧（Li-O）电池的实际应用至关重要。在此，我们通过第一性原理计算揭示了单层锗单硫属化物（2D-GeXs，X = S/Se）作为阴极催化材料的催化机理，并评估了其催化活性。对于2D-GeXs，具有环状结构的LiO是最终放电产物。自由能图表明，2D-GeSe比2D-GeS在能量上更有利，这是由于其氧还原反应（ORR）过电位（0.94 V）和析氧反应（OER）过电位（1.30 V）相当低，这源于其与LiO的结合较弱以及与插入的Li原子的结合较强。对电子性质的分析表明，2D-GeSe上LiO的最终产物诱导了半导体到半金属的转变。我们的结果表明，2D-GeSe是一种优异的非水Li-O电池阴极材料候选物，而2D-GeS不合适。
