Aqueous non-metallic ion batteries: Materials, mechanisms and design strategies

Aqueous non-metallic ion batteries (ANIBs) undoubtedly represent one of the best candidates for energy storage owing to their high safety, low manufacturing cost, and fast charging capability. In order to promote the development of ANIBs, we provide comprehensive summary and evaluation of the critical achievements. It is found that the latest works on ANIBs mainly focus on the explanation of the reaction mechanism and the exploration of host materials. First of all, ANIBs are divided into two main types (conversion-type and intercalation-type) according to their explicit mechanisms, and the specific distinction between them is illustrated. Secondly, modification methods and design strategies of host materials and corresponding systems, including nanosizing engineering, composite engineering, structural engineering and electrolyte engineering are put forward. Thirdly, the electrochemical performance of the above two kinds of systems is clarified and compared, including cycle life, specific capacity, capacity retention, average voltage, energy density and power density. Finally, major challenges and future perspectives for ANIBs to realize large-scale commercial applications are prospected as well.