We retrospect recent advances in rechargeable aqueous zinc-ion batteries system and the facing challenges of aqueous zinc-ion batteries. Importantly, some concerns and feasible solutions for achieving practical aqueous zinc-ion batteries are discussed in detail.

The manganese dissolution leading to sharp capacity decline as well as the sluggish reaction kinetic are still major issues for manganese‐based materials as aqueous zinc‐ion batteries (ZIBs) cathodes. Here, a potassium‐ion‐stabilized and oxygen‐defect K0.8Mn8O16 is reported as a high‐energy‐density and durable cathode for neutral aqueous ZIBs. A new insight into suppressing manganese dissolution via incorporation of K+ ions to intrinsically stabilize the Mn‐based cathodes is provided. A comprehensive study suggests that oxygen defects improve electrical conductivity and open the MnO6 polyhedron walls for ion diffusion, which plays a critical role in the fast reaction kinetics and capacity improvement of K0.8Mn8O16. In addition, direct evidence for the mechanistic details of simultaneous insertion and conversion reaction based on H+‐storage mechanism is demonstrated. As expected, a significant energy output of 398 W h kg−1 (based on the mass of cathode) and an impressive durability over 1000 cycles with no obvious capacity fading are obtained. Such a high‐energy Zn‐K0.8Mn8O16 battery, as well as the basic understanding of manganese dissolution and oxygen defects may open new opportunities toward high‐performance aqueous ZIBs.

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We report a series of ammonium vanadates as cathodes for aqueous ZIBs and provide insights into the origin of the enhanced electrochemical behaviors. The NH4V4O10 compound, with the largest interplanar spacing (9.8 Å), exhibits excellent electrochemical performance.

A V4+-V2O5 cathode with mixed vanadium valences was prepared via a novel synthetic method using VOOH as the precursor, and its zinc-ion storage performance was evaluated. The products are hollow spheres consisting of nanoflakes. The V4+-V2O5 cathode exhibits a prominent cycling performance, with a specific capacity of 140 mAh g−1 after 1000 cycles at 10 A g−1, and an excellent rate capability. The good electrochemical performance is attributed to the presence of V4+, which leads to higher electrochemical activity, lower polarization, faster ion diffusion, and higher electrical conductivity than V2O5 without V4+. This engineering strategy of valence state manipulation may pave the way for designing high-performance cathodes for elucidating advanced battery chemistry.

Biphasic and multiphasic compounds have been well clarified to achieve extraordinary electrochemical properties as advanced energy storage materials. Yet the role of phase boundaries in improving the performance is remained to be illustrated. Herein, we reported the biphasic vanadate, that is, Na1.2V3O8/K2V6O16·1.5H2O (designated as Na0.5K0.5VO), and detected the novel interfacial adsorption–insertion mechanism induced by phase boundaries. First‐principles calculations indicated that large amount of Zn2+ and H+ ions would be absorbed by the phase boundaries and most of them would insert into the host structure, which not only promote the specific capacity, but also effectively reduce diffusion energy barrier toward faster reaction kinetics. Driven by this advanced interfacial adsorption–insertion mechanism, the aqueous Zn/Na0.5K0.5VO is able to perform excellent rate capability as well as long‐term cycling performance. A stable capacity of 267 mA h g−1 after 800 cycles at 5 A g−1 can be achieved. The discovery of this mechanism is beneficial to understand the performance enhancement mechanism of biphasic and multiphasic compounds as well as pave pathway for the strategic design of high‐performance energy storage materials.

We report the NH 4 + intercalated V 2 O 5 , i.e. (NH 4 ) 2 V 10 O 25 •8H 2 O, with excellent electrochemical performance as cathode in aqueous zinc-ion battery (ZIBs), as compared to V 2 O 5 , Na 5 V 12 O 32 and K 2 V 8 O 21 . This work reveals that the ionic conductivity of Zn 2+ can be enhanced by introducing cations into the V 2 O 5 framework and the vanadium oxygen structural units will be rearranged. Compared to a single layer of vanadium pentoxide consisting solely of VO 5 units, the electrochemical performance of the structural units rearranged vanadates shows a significant improvement. As a result, the obtained (NH 4 ) 2 V 10 O 25 •8H 2 O delivers high discharge capacity (376 mA h g −1 at 0.5 A g −1 ), superior rate capability up to 10 A g −1 , excellent cycling stability (a capacity retention over 93% for 1000 cycles) and high energy density (341 Wh kg −1 ).