Wu Feixiang, Chu Fulu, Ferrero Guillermo A, Sevilla Marta, Fuertes Antonio B, Borodin Oleg, Yu Yan, Yushin Gleb
School of Metallurgy and Environment, Engineering Research Center of the Ministry of Education for Advanced Battery Materials, Central South University, Changsha 410083, P.R. China.
Instituto Nacional del Carbón (CSIC), Fco. Pintado Fe 26, Oviedo 33011, Spain.
Nano Lett. 2020 Jul 8;20(7):5391-5399. doi: 10.1021/acs.nanolett.0c01778. Epub 2020 Jun 4.
Polysulfide shuttle effects, active material losses, formation of resistive surface layers, and continuous electrolyte consumption create a major barrier for the lightweight and low-cost lithium-sulfur (Li-S) battery adoption. Tuning electrolyte composition by using additives and most importantly by substantially increasing electrolyte molarity was previously shown to be one of the most effective strategies. Contrarily, little attention has been paid to dilute and super-diluted LiTFSI/DME/DOL/LiNO based-electrolytes, which have been thought to aggravate the polysulfide dissolution and shuttle effects. Here we challenge this conventional wisdom and demonstrate outstanding capabilities of a dilute (0.1 mol L of LiTFSI in DME/DOL with 1 wt. % LiNO) electrolyte to enable better electrode wetting, greatly improved high-rate capability, and stable cycle performance for high sulfur loading cathodes and low electrolyte/sulfur ratio in Li-S cells. Overall, the presented study shines light on the extraordinary ability of such electrolyte systems to suppress short-chain polysulfide dissolution and polysulfide shuttle effects.
多硫化物穿梭效应、活性物质损失、电阻性表面层的形成以及持续的电解液消耗，是阻碍锂硫（Li-S）电池实现轻量化和低成本应用的主要障碍。此前研究表明，通过使用添加剂，尤其是大幅提高电解液摩尔浓度来调整电解液成分，是最有效的策略之一。相反，对于稀释和超稀释的基于双（三氟甲基磺酰）亚胺锂/二甲氧基乙烷/1,3-二氧戊环/硝酸锂的电解液，人们关注较少，因为这类电解液被认为会加剧多硫化物的溶解和穿梭效应。在此，我们对这一传统观念提出质疑，并证明了一种稀释电解液（在二甲氧基乙烷/1,3-二氧戊环中含有0.1 mol/L双（三氟甲基磺酰）亚胺锂和1 wt.%硝酸锂）具有出色的性能，它能够实现更好的电极浸润效果，显著提升高倍率性能，并使锂硫电池中高硫负载阴极和低电解液/硫比的情况下具备稳定的循环性能。总体而言，本研究揭示了此类电解液体系在抑制短链多硫化物溶解和多硫化物穿梭效应方面的卓越能力。
