Proton storage in rechargeable aqueous zinc‐ion batteries (ZIBs) is attracting extensive attention owing to the fast kinetics of H+ insertion/extraction. However, it has not been achieved in organic materials‐based ZIBs with a mild electrolyte. Now, aqueous ZIBs based on diquinoxalino [2,3‐a:2′,3′‐c] phenazine (HATN) in a mild electrolyte are developed. Electrochemical and structural analysis confirm for the first time that such Zn–HATN batteries experience a H+ uptake/removal behavior with highly reversible structural evolution of HATN. The H+ uptake/removal endows the Zn–HATN batteries with enhanced electrochemical performance. Proton insertion chemistry will broaden the horizons of aqueous Zn–organic batteries and open up new opportunities to construct high‐performance ZIBs.

The electrochemical performance of vanadiumoxide-based cathodes in aqueous zinc-ion batteries (ZIBs) depends on their degree of crystallinity and composite state with carbon materials. An in situ electrochemical induction strategy was developed to fabricate a metal-organic-framework-derived composite of amorphous V 2 O 5 and carbon materials (a-V 2 O 5 @C) for the first time, where V 2 O 5 is in an amorphous state and uniformly distributed in the carbon framework. The amorphous structure endows V 2 O 5 with more isotropic Zn 2+ diffusion routes and active sites, resulting in fast Zn 2+ transport and high specific capacity. The porous carbon framework provides a continuous electron transport pathway and ion diffusion channels. As a result, the a-V 2 O 5 @C composites display extraordinary electrochemical performance. This work will pave the way toward design of ZIB cathodes with superior rate performance.

Organic electroactive compounds are attractive to serve as the cathode materials of aqueous zinc‐ion batteries (ZIBs) because of their resource renewability, environmentally friendliness and structural diversity. Up to now, various organic electrode materials have been developed and different redox mechanisms are observed in aqueous Zn/organic battery systems. In this Minireview, we present the recent developments in the energy storage mechanisms and design of the organic electrode materials of aqueous ZIBs, including carbonyl compounds, imine compounds, conductive polymers, nitronyl nitroxides, organosulfur polymers and triphenylamine derivatives. Furthermore, we highlight the design strategies to improve their electrochemical performance in the aspects of specific capacity, output voltage, cycle life and rate capability. Finally, we discuss the challenges and future perspectives of aqueous Zn/organic batteries.

Conventional aqueous batteries usually suffer from serious capacity loss under subzero conditions owing to the freeze of electrolytes. To realize the utilization of aqueous batteries in extremely cold climates, low-temperature aqueous battery systems have to be developed. Herein, an aqueous Pbquinone battery based on p-chloranil/reduced graphene oxide (PCHL-rGO) in H 2 SO 4 electrolyte is developed. Such aqueous Pb/PCHL-rGO batteries display H + insertion chemistry, which endows the batteries with fast reaction kinetics and high rate capability. In addition, the hydrogen bonds between water molecules can be significantly damaged in electrolyte by modulating the interaction between SO 4 2À and water molecules, lowering the freezing point of electrolyte. As a result, the Pb/ PCHL-rGO batteries deliver extraordinary electrochemical performance even at À70 8C. This work will broaden the horizons of aqueous batteries and open up new opportunities to construct low-temperature aqueous batteries.

Aqueous rechargeable metal batteries are intrinsically safe due to the utilization of low-cost and non-flammable water-based electrolyte solutions. However, the discharge voltages of these electrochemical energy storage systems are often limited, thus, resulting in unsatisfactory energy density. Therefore, it is of paramount importance to investigate alternative aqueous metal battery systems to improve the discharge voltage. Herein, we report reversible manganese-ion intercalation chemistry in an aqueous electrolyte solution, where inorganic and organic compounds act as positive electrode active materials for Mn2+ storage when coupled with a Mn/carbon composite negative electrode. In one case, the layered Mn0.18V2O5·nH2O inorganic cathode demonstrates fast and reversible Mn2+ insertion/extraction due to the large lattice spacing, thus, enabling adequate power performances and stable cycling behavior. In the other case, the tetrachloro-1,4-benzoquinone organic cathode molecules undergo enolization during charge/discharge processes, thus, contributing to achieving a stable cell discharge plateau at about 1.37 V. Interestingly, the low redox potential of the Mn/Mn2+ redox couple vs. standard hydrogen electrode (i.e., −1.19 V) enables the production of aqueous manganese metal cells with operational voltages higher than their zinc metal counterparts.