Department of Chemical Engineering, The City College of New York, 160 Convent Avenue, New York, New York 10031, United States.
J Phys Chem Lett. 2023 Mar 9;14(9):2378-2386. doi: 10.1021/acs.jpclett.3c00150. Epub 2023 Feb 27.
Rechargeable zinc (Zn) metal batteries are attractive for use as electrochemical energy storage systems on a global scale because of the low cost, high energy density, inherent safety, and strategic resource security of Zn metal. However, at low temperatures, Zn batteries typically suffer from high electrolyte viscosity and unfavorable ion transport properties. Here, we studied reversible Zn electrodeposition in mixtures of 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide ([EMIm]TFSI) ionic liquid, γ-butyrolactone (GBL) organic solvent, and Zn(TFSI) zinc salt. The electrolyte mixtures enabled reversible Zn electrodeposition at temperatures as low as -60 °C. An electrolyte composed of 0.1 M Zn(TFSI) in [EMIm]TFSI:GBL with a volume ratio of 1:3 formed a deep eutectic solvent that optimized electrolyte conductivity, viscosity, and the zinc diffusion coefficient. Liquid-state H and C nuclear magnetic resonance (NMR) spectroscopy and molecular dynamic (MD) simulations indicate increased formation of contact ion pairs and the reduction of ion aggregates are responsible for the optimal composition.
可充电锌 (Zn) 金属电池因其锌金属的低成本、高能量密度、固有安全性和战略性资源安全性，作为全球电化学储能系统极具吸引力。然而，在低温下，Zn 电池通常受到高电解质粘度和不利的离子传输性能的影响。在这里，我们研究了在 1-乙基-3-甲基-咪唑双（三氟甲基磺酰基）亚胺 ([EMIm]TFSI) 离子液体、γ-丁内酯 (GBL) 有机溶剂和 Zn(TFSI) 锌盐混合物中的可逆 Zn 电沉积。电解质混合物能够在低至-60°C 的温度下实现可逆 Zn 电沉积。由 0.1 M Zn(TFSI) 在 [EMIm]TFSI:GBL 中的体积比为 1:3 组成的电解质形成了深共晶溶剂，优化了电解质电导率、粘度和锌扩散系数。液体状态的 H 和 C 核磁共振 (NMR) 光谱和分子动力学 (MD) 模拟表明，接触离子对的形成增加和离子聚集体的减少是最佳组成的原因。
