School of Resource and Environmental Sciences, Hubei Biomass-Resource Chemistry and Environmental Biotechnology Key Laboratory, Wuhan University, Wuhan, 430079, China.
College of Chemical Engineering, Nanjing Forestry University, Jiangsu Provincial Key Lab for the Chemistry and Utilization of Agro-Forest Biomass, Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, International Innovation Center for Forest Chemicals and Materials, Nanjing, 210037, China.
Adv Mater. 2023 May;35(21):e2210789. doi: 10.1002/adma.202210789. Epub 2023 Apr 2.
The strong reactivity of water in aqueous electrolytes toward metallic zinc (Zn), especially at aggressive operating conditions, remains the fundamental obstacle to the commercialization of aqueous zinc metal batteries (AZMBs). Here, a water-immiscible ionic liquid diluent 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)amide (EmimFSI) is reported that can substantially suppress the water activity of aqueous electrolyte by serving as a "water pocket", enveloping the highly active H O-dominated Zn solvates and protecting them from parasitic reactions. During Zn deposition, the cation Emim and anion FSI function respectively in mitigating the tip effect and regulating the solid electrolyte interphase (SEI), thereby favoring a smooth Zn deposition layer protected by inorganic species-enriched SEI featuring high uniformity and stability. Combined with the boosted chemical/electrochemical stability endowed by the intrinsic merits of ionic liquid, this ionic liquid-incorporated aqueous electrolyte (IL-AE) enables the stable operation of Zn||Zn V O ·nH O cells even at a challenging temperature of 60 °C (>85% capacity retention over 400 cycles). Finally, as an incidental but practically valuable benefit, the near-zero vapor pressure nature of ionic liquid allows the efficient separation and recovery of high-value components from the spent electrolyte via a mild and green approach, promising the sustainable future of IL-AE in realizing practical AZMBs.
水在水基电解液中对金属锌（Zn）的强反应性，特别是在苛刻的工作条件下，仍然是阻碍水性锌金属电池（AZMBs）商业化的根本障碍。在这里，报告了一种不溶于水的离子液体稀释剂 1-乙基-3-甲基咪唑双（氟磺酰基）酰胺（EmimFSI），它可以作为“水袋”，包裹高活性的 H2O 主导的 Zn 溶剂化物，并防止它们发生寄生反应，从而显著降低水基电解液的水活度。在 Zn 沉积过程中，阳离子 Emim 和阴离子 FSI 分别在减轻尖端效应和调节固体电解质界面（SEI）方面发挥作用，从而有利于由富含无机物种的 SEI 保护的平滑 Zn 沉积层，其具有高均匀性和稳定性。结合离子液体固有的化学/电化学稳定性的提高，这种离子液体掺入的水基电解液（IL-AE）使 Zn||ZnV2O5·nH2O 电池即使在 60°C 的苛刻温度下（超过 400 次循环后保持 85%以上的容量）也能稳定运行。最后，作为一个偶然但实际有价值的好处，离子液体的近零蒸气压特性允许通过温和且绿色的方法从废电解液中高效分离和回收高价值成分，有望为 IL-AE 在实现实际 AZMBs 方面的可持续未来提供支持。
