Rechargeable batteries that use water as the electrolyte are called aqueous batteries. Compared to secondary batteries that use organic solutions as the electrolyte, these batteries are not only simpler to manufacture, but also offer multiple advantages such as safety, affordability, and excellent high-current discharge performance. Given these characteristics, aqueous batteries have shown great potential for development in large-scale energy storage systems and power supply for electric vehicles.
In 1994, Dahn et al.'s research team first published a lithium-ion battery using an aqueous solution as an electrolyte in the journal Science.The positive electrode material of this battery is LiMn2O4, while the negative electrode is VO2, and the electrolyte used is a neutral Li2SO4 solution. This battery has an average operating voltage of approximately 1.5V and a theoretical specific energy of 75 Wh/kg, which in practical applications approaches 40 Wh/kg. This value exceeds that of lead-acid batteries (approximately 30 Wh/kg) and is comparable to nickel-cadmium batteries, although its cycle stability is relatively poor.
Subsequently, in 2000, Toki's team from Japan reported another aqueous lithium-ion battery design, which used LiV3Og as the negative electrode material and LiNiO10.81CO0.19O2 as the positive electrode material, and also used Li2SO4 solution as the electrolyte.
In 2006, a research group led by Academician Chen Liquan of the Institute of Physics, Chinese Academy of Sciences, reported an aqueous lithium-ion battery using TiPO₄ and LiT₂(PO₃)₃ as the negative electrode, LiMnO₄ as the positive electrode, and LiNO₃ solution as the electrolyte.
In 2007, Professor Wu Yuping's research team at Fudan University also published a water-based lithium-ion battery with LiVO as the negative electrode, LiMnO4 as the positive electrode, and LINO as the electrolyte solution.
In 2007, Professor Wu Yuping's research team at Fudan University also published a water-based lithium-ion battery with LiVO as the negative electrode, LiMnO4 as the positive electrode, and LINO as the electrolyte solution.
Since then, based on the reaction mechanisms of positive and negative electrode materials, the academic community has conducted extensive research on several lithium-ion battery systems based on aqueous electrolytes.
These systems are characterized by using compounds capable of intercalating lithium ions as active materials at both their positive and negative electrodes. During charge-discharge cycles, lithium ions can reversibly move between the two electrodes, achieving energy storage and release. Currently, aqueous lithium-ion battery technology faces multiple obstacles in its development. Compared to organic electrolytes, the chemical and electrochemical changes experienced by ion-intercalating compounds in aqueous battery electrolyte systems are more complex, easily triggering various side reactions, including but not limited to the interaction between electrode materials and water or oxygen, the co-intercalation of protons and metal ions, hydrogen/oxygen release processes, and the dissolution of electrode materials in water.
