With the increased penetration of energy storage devices in daily life, safety hazard and energy density issues are attracting greater and greater interest. Conventional liquid electrolytes suffer from leakage, flammability, gas evolution, dendrite hazards, and so on, especially when matching with high-energy-density metal anodes. Though solid-state electrolytes (SSEs) are promising candidates for the next-generation safe and high energy density energy storage system, individual SSE fails to meet the asynchronous demands of cathode and anode, because of their intrinsic solid chemistry properties. Among numerous modified approaches related to SSEs chemistry, asymmetric SSEs (ASSEs) which have more than one SSE and multilayer structure take advantage of individual SSE layers and complement each other’s disadvantages, showing Janus abilities. However, there are few reviews about ASSEs. Also, the problem of interface compatibility the between different electrolytes as well as the interface of electrodes and electrolytes is hindering the development of ASSEs. This review comprehensively outlines the state of the art of ASSEs. Additionally, it summarizes the advantages and functions of ASSEs with the unique structure for different energy storage. Furthermore, the interfacial compatibility and corresponding evaluation methods are discussed. Finally, an outlook on how ASSEs will develop in the future energy storage applications is proposed.

As next-generation rechargeable alternatives, zinc-based energy storage devices (ZESs) are being intensely explored due to their merits of abundant resource, low cost, safety and environmental benignity. However, ZESs face a succession of critical challenges on pursuing advancing performance, including the stability and kinetics of cathode, stability and transport of zinc electrolyte, reversibility and deep utilization of metallic Zn anode. Biomass, possessing unique molecular structures with abundant functionals groups, motivates the interdisciplinary field emerging from biomass and aqueous rechargeable battery. Concerning its high compatibility with ZES design, we here summarize the application of biomass materials in ZESs from the aspects of cathode, electrolyte, membrane/separator and Zn anode, with their corresponding operational mechanisms and attractive functionalities from polymeric structures. Accordingly, the outlooks and perspectives are provided, regarding current challenges and future directions. We anticipate our minireview paves way on exploring the roles of biomass in aqueous rechargeable batteries.