Yu Bo, Huang Aijian, Srinivas Katam, Zhang Xiaojuan, Ma Fei, Wang Xinqiang, Chen Dongjiang, Wang Bin, Zhang Wanli, Wang Zegao, He Jiarui, Chen Yuanfu
State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054, China.
Department of Chemistry, Tsinghua University, Beijing 100084, China.
ACS Nano. 2021 Aug 24;15(8):13279-13288. doi: 10.1021/acsnano.1c03011. Epub 2021 Aug 5.
It is still challenging to develop sulfur electrodes for Li-S batteries with high electrical conductivity and fast kinetics, as well as efficient suppression of the shuttling effect of lithium polysulfides. To address such issues, herein, polar MoTe with different phases (2H, 1T, and 1T') were deeply investigated by density functional theory calculations, suggesting that the 1T'-MoTe displays concentrated density of states (DOS) near the Fermi level with high conductivity. By optimization of the synthesis, 1T'-MoTe quantum dots decorated three-dimensional graphene (MTQ@3DG) was prepared to overcome these issues, and it accomplished exceptional performance in Li-S batteries. Owing to the chemisorption and high catalytic effect of 1T'-MoTe quantum dots, MTQ@3DG/S exhibits highly reversible discharge capacity of 1310.1 mAh g at 0.2 C with 0.026% capacity fade rate per cycle over 600 cycles. The adsorption calculation demonstrates that the conversion of LiS to LiS is the rate-limiting step where the Gibbs free energies are 1.07 eV for graphene and 0.97 eV for 1T'-MoTe, revealing the importance of 1T'-MoTe. Furthermore, Raman spectroscopy investigation proved the suppression of the shuttle effect of LiPSs in MTQ@3DG/S cells during the cycle.
开发用于锂硫电池的具有高电导率、快速动力学以及有效抑制多硫化锂穿梭效应的硫电极仍然具有挑战性。为了解决这些问题，本文通过密度泛函理论计算对不同相（2H、1T和1T'）的极性碲化钼进行了深入研究，结果表明1T'-MoTe在费米能级附近具有集中的态密度（DOS）和高电导率。通过优化合成方法，制备了1T'-MoTe量子点修饰的三维石墨烯（MTQ@3DG）以克服这些问题，并且它在锂硫电池中表现出优异的性能。由于1T'-MoTe量子点的化学吸附和高催化作用，MTQ@3DG/S在0.2 C下表现出1310.1 mAh g的高度可逆放电容量，在600次循环中每循环的容量衰减率为0.026%。吸附计算表明，LiS向LiS的转化是速率限制步骤，其中石墨烯的吉布斯自由能为1.07 eV，1T'-MoTe的吉布斯自由能为0.97 eV，这揭示了1T'-MoTe的重要性。此外，拉曼光谱研究证明了在循环过程中MTQ@3DG/S电池中多硫化锂穿梭效应受到抑制。
