Feng Junan, Li Yahui, Yuan Jinshi, Zhao Yuling, Zhang Jianmin, Wang Fengyun, Tang Jie, Song Jianjun
College of Physics, Qingdao University, Qingdao, China.
National Engineering Research Center for Intelligent Electrical Vehicle Power System (Qingdao), College of Mechanical and Electrical Engineering, Qingdao University, Qingdao, China.
Front Chem. 2022 Feb 10;9:830485. doi: 10.3389/fchem.2021.830485. eCollection 2021.
Lithium sulfur (Li-S) battery has exhibited great application potential in next-generation high-density secondary battery systems due to their excellent energy density and high specific capacity. However, the practical industrialization of Li-S battery is still affected by the low conductivity of sulfur and its discharge product (LiS/LiS), the shuttle effect of lithium polysulfide (LiS, 4 ≤ n ≤ 8) during charging/discharging process and so on. Here, cobalt disulfide/reduced graphene oxide (CoS/rGO) composites were easily and efficiently prepared through an energy-saving microwave-assisted hydrothermal method and employed as functional interlayer on commercial polypropylene separator to enhance the electrochemical performance of Li-S battery. As a physical barrier and second current collector, the porous conductive rGO can relieve the shuttle effect of polysulfides and ensure fast electron/ion transfer. Polar CoS nanoparticles uniformly distributed on rGO provide strong chemical adsorption to capture polysulfides. Benefitting from the synergy of physical and chemical constraints on polysulfides, the Li-S battery with CoS/rGO functional separator exhibits enhanced conversion kinetics and excellent electrochemical performance with a high cycling initial capacity of 1,122.3 mAh g at 0.2 C, good rate capabilities with 583.9 mAh g at 2 C, and long-term cycle stability (decay rate of 0.08% per cycle at 0.5 C). This work provides an efficient and energy/time-saving microwave hydrothermal method for the synthesis of functional materials in stable Li-S battery.
锂硫（Li-S）电池因其优异的能量密度和高比容量，在下一代高密度二次电池系统中展现出巨大的应用潜力。然而，锂硫电池的实际工业化仍受到硫及其放电产物（Li₂S/Li₂Sₓ）导电性低、多硫化锂（Li₂Sₙ，4≤n≤8）在充放电过程中的穿梭效应等因素的影响。在此，通过节能微波辅助水热法轻松高效地制备了二硫化钴/还原氧化石墨烯（CoS₂/rGO）复合材料，并将其用作商用聚丙烯隔膜上的功能中间层，以提高锂硫电池的电化学性能。作为物理屏障和第二集流体，多孔导电的rGO可以减轻多硫化物的穿梭效应，并确保快速的电子/离子转移。均匀分布在rGO上的极性CoS₂纳米颗粒提供强大的化学吸附作用以捕获多硫化物。受益于对多硫化物的物理和化学约束协同作用，具有CoS₂/rGO功能隔膜的锂硫电池表现出增强的转化动力学和优异的电化学性能，在0.2 C下初始循环容量高达1122.3 mAh g，在2 C下具有583.9 mAh g的良好倍率性能，以及长期循环稳定性（在0.5 C下每循环衰减率为0.08%）。这项工作为稳定的锂硫电池中功能材料的合成提供了一种高效且节能/省时的微波水热法。
