Wang Yujue, Meng Yan, Zhang Zhaokun, Guo Yong, Xiao Dan
Institute of New Energy and Low-Carbon Technology (INELT), Sichuan University, Chengdu 610207, China.
School of Chemical Engineering, Sichuan University, Chengdu 610065, China.
ACS Appl Mater Interfaces. 2021 Apr 14;13(14):16545-16557. doi: 10.1021/acsami.1c02580. Epub 2021 Mar 31.
Lithium-sulfur (Li-S) battery with a very high theoretical energy density (∼2500 Wh kg) is a very promising alternative to the commercial lithium-ion battery as the next-generation energy storage device. However, the Li-S battery suffers from shuttle effect and Li dendrites growth due to the solubility of polysulfides in the electrolyte system and the inhomogeneous deposition of Li, resulting in short cycling life span, which is the major obstacle in its practical application. Herein, we report an additive, hexadecyltrioctylammonium iodide (HTOA-I), in the conventional electrolyte system, which shows trifunctional effect on extending Li-S battery cycle life. It can not only help us to form a protective solid-electrolyte interface (SEI) on the surface of Li anode so as to reduce the contact of polysulfides with Li but also hinder the shuttling of polysulfides to the Li anode due to the strong combination of large-sized HTOA with polysulfide anions (S), which retard the migration of S and cause homogeneous Li deposition owing to the large size and stronger trend of HTOA to be absorbed on Li anode as well. A new method of phosphorescence analysis for direct observation of polysulfides shuttling has been put forward for the first time, which can be further developed in future studies. The cell with the HTOA-I-added electrolyte system shows high cycling stability, retaining 83.4% of the initial capacity after 200 cycles at 1 A g and achieving 689 mAh g even after 1000 cycles. This cost-effective and facile approach will not increase the complexity of the battery manufacturing process. Compared to other electrolyte additives, the additive in our work, HTOA-I, has better positive effects on extending cycle life. This trifunctional electrolyte additive will inspire the design of other new additives and further promote the development of Li-S batteries.
锂硫（Li-S）电池具有非常高的理论能量密度（约2500 Wh/kg），作为下一代储能装置，是商用锂离子电池非常有前景的替代品。然而，由于多硫化物在电解质体系中的溶解性以及锂的不均匀沉积，Li-S电池存在穿梭效应和锂枝晶生长问题，导致循环寿命短，这是其实际应用中的主要障碍。在此，我们报道了一种在传统电解质体系中的添加剂十六烷基三辛基碘化铵（HTOA-I），它对延长Li-S电池循环寿命具有三功能作用。它不仅有助于在锂阳极表面形成保护性固体电解质界面（SEI），以减少多硫化物与锂的接触，还由于大尺寸的HTOA与多硫化物阴离子（S）的强烈结合而阻碍多硫化物向锂阳极的穿梭，这减缓了S的迁移，并由于HTOA尺寸大且更倾向于吸附在锂阳极上而导致锂均匀沉积。首次提出了一种用于直接观察多硫化物穿梭的磷光分析新方法，该方法可在未来研究中进一步发展。添加了HTOA-I电解质体系的电池显示出高循环稳定性，在1 A g下200次循环后保留了初始容量的83.4%，甚至在1000次循环后仍达到689 mAh/g。这种经济高效且简便的方法不会增加电池制造过程的复杂性。与其他电解质添加剂相比，我们工作中的添加剂HTOA-I对延长循环寿命具有更好的积极效果。这种三功能电解质添加剂将激发其他新型添加剂的设计，并进一步推动Li-S电池发展。
