Department of Engineering and Systems Science, National Tsing Hua University , Hsinchu 30013, Taiwan.
Nano Science and Technology Program, Taiwan International Graduate Program, Academia Sinica, National Tsing Hua University , Hsinchu 30013, Taiwan.
ACS Nano. 2017 Dec 26;11(12):12436-12445. doi: 10.1021/acsnano.7b06478. Epub 2017 Dec 11.
In this paper we describe a modified (AEG/CH) coated separator for Li-S batteries in which the shuttling phenomenon of the lithium polysulfides is restrained through two types of interactions: activated expanded graphite (AEG) flakes interacted physically with the lithium polysulfides, while chitosan (CH), used to bind the AEG flakes on the separator, interacted chemically through its abundance of amino and hydroxyl functional groups. Moreover, the AEG flakes facilitated ionic and electronic transfer during the redox reaction. Live H-cell discharging experiments revealed that the modified separator was effective at curbing polysulfide shuttling; moreover, X-ray photoelectron spectroscopy analysis of the cycled separator confirmed the presence of lithium polysulfides in the AEG/CH matrix. Using this dual functional interaction approach, the lifetime of the pure sulfur-based cathode was extended to 3000 cycles at 1C-rate (1C = 1670 mA/g), decreasing the decay rate to 0.021% per cycle, a value that is among the best reported to date. A flexible battery based on this modified separator exhibited stable performance and could turn on multiple light-emitting diodes. Such modified membranes with good mechanical strength, high electronic conductivity, and anti-self-discharging shield appear to be a scalable solution for future high-energy battery systems.
本文介绍了一种改性（AEG/CH）涂层锂硫电池隔膜，其中通过两种相互作用来抑制锂多硫化物的穿梭现象：一方面，活性膨胀石墨（AEG）薄片与锂多硫化物发生物理相互作用；另一方面，用于将 AEG 薄片固定在隔膜上的壳聚糖（CH）通过其丰富的氨基和羟基官能团发生化学相互作用。此外，AEG 薄片在氧化还原反应过程中促进了离子和电子的传递。恒电流放电实验表明，改性隔膜能有效抑制多硫化物的穿梭；此外，循环后的隔膜的 X 射线光电子能谱分析证实了锂多硫化物存在于 AEG/CH 基质中。通过这种双重功能相互作用的方法，基于纯硫的正极的寿命延长至 1C 倍率（1C = 1670 mA/g）下的 3000 次循环，衰减率降低至 0.021%/循环，这是迄今为止报道的最佳值之一。基于这种改性隔膜的柔性电池表现出稳定的性能，并且可以点亮多个发光二极管。这种具有良好机械强度、高电子导电性和抗自放电屏蔽的改性膜似乎是未来高能电池系统的一种可扩展解决方案。
