The renaissance of “water-in-salt” electrolytes for energy storage devices

In recent years, there has been a growing focus on the demand for alternate electrolytes. There is a requirement to tackle the drawbacks of costly alternatives like lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in energy storage applications. This study explores a range of lithium salts (LiX) as potential substitutes, focusing on their suitability for "water-in-salt" electrolytes. By investigating electrolytes with concentrations varying from low to superconcentrated levels, the physical and electrochemical properties of LiX were thoroughly examined. Parameters such as viscosity, pH, conductivity, density, and temperature variations during mixing were meticulously evaluated to understand the behavior of LiX electrolytes.Electrochemical characterization using carbon-based materials in a three-electrode configuration and subsequent integration into coin cell supercapacitors provided insights into the performance of different LiX electrolytes. Notably, while highly concentrated LiX electrolytes, particularly LiCl, demonstrated the potential to expand the operating voltage window, challenges related to corrosion were identified, necessitating further mitigation strategies.Studies have also shown redox properties in LiBr and LiI electrolytes, with increased concentration observed to accelerate the redox process while maintaining voltage stability. LiNO3 becomes It is a potent alternative electrolyte. This is due to its potential being comparable to LiTFSI and its cost-effectiveness.Cost analysis shows that LiNO3 is a feasible option in terms of energy density. It has the potential for further optimization through the use of LiBr and LiI as redox enhancing electrolytes. This comprehensive review not only provides valuable insights into the physical and electrochemical characteristics of LiX electrolytes, but also highlights the potential of these electrolytes as alternatives. In the electrolyte system "Water in salt". Overall, this research contributes to improving our understanding of LiX electrolytes and leads to their practical use in next-generation energy storage devices. It offers a promising path towards cost-effective and efficient energy storage solutions.