Progress in Aqueous Rechargeable Sodium-Ion Batteries

Sodium (Na) is one of the more abundant elements on earth and exhibits similar chemical properties as lithium (Li), indicating that Na could be applied to a similar battery system. Like aqueous Li-ion batteries, aqueous sodium-ion batteries (ASIBs) are also demonstrated to be one of the most promising stationary power sources for sustainable energies such as wind and solar power. Compared to traditional nonaqueous batteries, ASIBs may solve the safety problems associated with the highly toxic and flammable organic electrolyte in the traditional lithium-ion and sodium-ion batteries. During the past decades, many efforts are made to improve the performance of the ASIBs. The present review focuses on the latest advances in the exploration and development of ASIB systems and related components, including cathodes, anodes, and electrolytes. Previously reported studies are briefly summarized, together with the presentation of new findings based on the electrochemical performance, cycling stability, and morphology approaches. In addition, the main opportunities, achievements, and challenges in this field are briefly commented and discussed.