Yang Liwen, Wang Yang, Li Qian, Li Yuan, Chen Yanxiao, Liu Yuxia, Wu Zhenguo, Wang Gongke, Zhong Benhe, Song Yang, Xiang Wei, Zhong Yanjun, Guo Xiaodong
School of Chemical Engineering, Sichuan University, No. 24 South Section 1, Yihuan Road, Chengdu, 610065, PR China.
The Key Laboratory of Life-Organic Analysis, Key Laboratory of Pharmaceutical Intermediates and Analysis of Natural Medicine, School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu, 273165, Shandong, PR China.
Nanoscale. 2021 Mar 12;13(9):5058-5068. doi: 10.1039/d1nr00034a.
The dissolution of polysulfides in an electrolyte is a thermodynamically favorable process, which in theory means that the shuttle effect in lithium-sulfur batteries (LSBs) cannot be completely suppressed. So, it is very important to modify the separator to prevent the migration of polysulfides to the lithium anode. The traditional coating modification process of the separator is cumbersome and uses a solvent that is harmful to the environment, and too many inactive components affect the overall energy density of the battery. It is thus imperative to find a simple and environmentally friendly modification process of the separator. In this study, a fast chemical film-forming method is proposed to modify the separator of a lithium-sulfur battery using tannic acid (TA) and cobalt ions (Co2+). This method requires only simple steps and environmentally friendly raw materials to obtain a thin coating (only 5.83 nm) that can effectively inhibit the shuttle effect. The lithium-sulfur battery with the TA-Co separator shows superior long cycle performance. After 500 cycles at 0.5 C, the capacity decay rate of each cycle is only 0.065%. On the other hand, the TA-Co separator can inhibit the growth of lithium dendrites and help to build a stable lithium anode, which can exhibit minimal polarization (56 mV) in a lithium-lithium symmetrical battery at the current density of 2 mA cm-2. The rapid and simple modification method proposed in this study has a certain reference value for the future large-scale application of lithium sulfur batteries.
多硫化物在电解质中的溶解是一个热力学上有利的过程，从理论上讲，这意味着锂硫电池（LSB）中的穿梭效应无法被完全抑制。因此，对隔膜进行改性以防止多硫化物迁移到锂负极非常重要。传统的隔膜涂层改性工艺繁琐，且使用对环境有害的溶剂，过多的非活性成分会影响电池的整体能量密度。因此，必须找到一种简单且环保的隔膜改性工艺。在本研究中，提出了一种快速化学成膜方法，使用单宁酸（TA）和钴离子（Co2+）对锂硫电池的隔膜进行改性。该方法仅需简单步骤和环保原料就能获得能有效抑制穿梭效应的薄涂层（仅5.83纳米）。采用TA-Co隔膜的锂硫电池表现出优异的长循环性能。在0.5 C下循环500次后，每次循环的容量衰减率仅为0.065%。另一方面，TA-Co隔膜可以抑制锂枝晶的生长，并有助于构建稳定的锂负极，在2 mA cm-2的电流密度下，锂-锂对称电池中其极化最小（56 mV）。本研究提出的快速且简单的改性方法对锂硫电池未来的大规模应用具有一定的参考价值。
