Recent advances of aqueous rechargeable lithium/sodium ion batteries: key electrode materials and electrolyte design strategies

Aqueous ion batteries are receiving increasing attention as a means of achieving carbon neutrality due to their advantages in terms of low cost, safety, and environmental friendliness. Unlike aqueous multivalent metal cation batteries, monovalent metal cations in aqueous ion batteries have been favored by researchers for their lower reduction potentials, smaller hydration ion radii and hydration enthalpies, and faster ion migration rates. However, the research on aqueous monovalent cation batteries is still in the experimental exploration stage due to several limitations. The lower operating voltage and energy densities of aqueous monovalent cation batteries are mainly due to the narrow electrochemical stability window of the electrolyte, limited compatible electrode materials, and unresolved challenges such as the hydrogen evolution reaction and oxygen evolution reaction. This paper aims to address the issues related to aqueous monovalent lithium/sodium ion batteries. A specific discussion will be provided on the electrode materials, the dissolution structure of the electrolyte, and the design strategy of the battery. Additionally, this paper will also present insights into the challenges faced during the research process and the prospects for the development of aqueous lithium/sodium ion batteries.