Chivukula Kalyan Sundar Krishna, Zhao Yansong
Department of Safety, Chemistry and Biomedical Laboratory Sciences, Western Norway University of Applied Sciences (HVL) 5063 Bergen Norway
RSC Adv. 2025 Jul 17;15(31):25310-25321. doi: 10.1039/d5ra02901e. eCollection 2025 Jul 15.
Vanadium redox flow batteries (VRFBs) have emerged as a promising contenders in the field of electrochemical energy storage primarily due to their excellent energy storage capacity, scalability, and power density. However, the development of VRFBs is hindered by its limitation to dissolve diverse vanadium salts in the aqueous solution without significantly impacting the viscosity and thereby, the operational efficiency. To address this challenge, a novel aqueous ionic-liquid based electrolyte comprising 1-butyl-3-methylimidazolium chloride (BmimCl) and vanadium chloride (VCl) was synthesized to enhance the solubility of the vanadium salt and aid in improving the efficiency. The synthesized novel electrolyte combination showcased a maximum theoretical energy density of approximately 44.24 Wh L, a dynamic viscosity of 36.62 mPa s along with a stable potential window of approximately 1.8 V, and an ionic conductivity of 0.201 S cm at room temperature. Furthermore, the aqueous ionic-liquid based VRFB demonstrated an appreciable coulombic efficiency and capacity retention of greater than 85% at a discharge current of 5 mA. The maximum achievable concentration utilizing deionized water was obtained to be 2 M, which can be significantly enhanced by utilizing various component combinations of organic solvents, and ionic liquids to unlock the full potential of VRFBs. This novel electrolyte composition provides a promising pathway for improving the energy density and operational efficiency of VRFBs, paving the way for advanced energy storage solutions.
钒氧化还原液流电池（VRFBs）已成为电化学储能领域中颇具潜力的竞争者，主要得益于其出色的储能容量、可扩展性和功率密度。然而，VRFBs的发展受到限制，即难以在不显著影响粘度从而不影响运行效率的情况下，将多种钒盐溶解于水溶液中。为应对这一挑战，合成了一种新型的基于水性离子液体的电解质，其由1-丁基-3-甲基咪唑氯化物（BmimCl）和氯化钒（VCl）组成，以提高钒盐的溶解度并有助于提高效率。合成的新型电解质组合展现出约44.24 Wh L的最大理论能量密度、36.62 mPa s的动态粘度、约1.8 V的稳定电位窗口以及室温下0.201 S cm的离子电导率。此外，基于水性离子液体的VRFB在5 mA的放电电流下表现出可观的库仑效率和大于85%的容量保持率。利用去离子水可达到的最大浓度为2 M，通过使用有机溶剂和离子液体的各种组分组合可显著提高该浓度，从而释放VRFBs的全部潜力。这种新型电解质组合物为提高VRFBs的能量密度和运行效率提供了一条有前景的途径，为先进的储能解决方案铺平了道路。
