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Aqueous zinc-ion batteries offer the greatest promise as an alternative technology for low-cost and high-safety energy storage. However, the development of high-performance cathode materials and their compatibility with aqueous electrolytes are major obstacles to their practical applications. Herein, we report the synthesis of orthorhombic V2O5·nH2O nanorods as cathodes for aqueous zinc batteries. As a result, the electrode delivers a reversible capacity as high as 320 mAh g−1 at 1.0 A g−1 and long-term cycling stability in a wide window of 0.2 to 1.8 V using a mild ZnSO4 aqueous electrolyte. The superior performance can be attributed to the improved stability of materials, inhibited electrolyte decomposition and facilitated charge transfer kinetics of such materials for aqueous zinc storage. Furthermore, a full cell using microsized Zn powder as an anode within capacity-balancing design exhibits high capacity and stable cycling performance, proving the feasibility of these materials for practical application. [ABSTRACT FROM AUTHOR]

[Display omitted] Aqueous rechargeable batteries offer a safe alternative for electrochemical energy storage, integrating cost-efficiency and energy density to meet the demand for stationary applications. Recent efforts have focused on the improvement of electrode materials in aqueous electrolytes, particularly the cycle life and energy reliability of batteries. The anion intercalation chemistry in graphite could be an alternative cathode candidate, often requiring an upper cut-off potential above 4.5 V vs. Li+/Li. Such a potential readily exceeds the electrochemical stability windows of water-based electrolytes. Herein, we provide a progress report and critical comment on the reversible intercalation chemistry in graphite compounds, i.e. , anion and halogen intercalations, for the development of economical, high-energy aqueous rechargeable batteries. In addition, this review focuses on the charge carrier species, their charge storage mechanisms and battery configurations, aiming to provide solutions to solve the remaining key challenges for aqueous batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • The tunnel-type Ti-substituted Na 0.44 MnO 2 was investigated as cathode for aqueous zinc batteries. • The Ti-substitution can efficiently improve the electrochemical kinetics with superior high-rate capability and cycling stability. • The facilitated reaction mechanism with stepwise Zn2+ and H+ insertions was versified. • The optimal Na 0.44 Mn 0.78 Ti 0.22 O 2 material exhibits a high reversible capacity and a cycling life record for 2400 cycles. The tunnel-type sodium manganese oxide (Na 0.44 MnO 2) materials are considered as promising cathode candidates for rechargeable batteries due to their low cost and sustainability. However, the direct implementation in aqueous batteries, as an emerging energy storage technology, was not fully realized in terms of the reversibility and long-cycling stability. Herein, the tunnel-type Ti-substituted Na 0.44 MnO 2 (NMTO) is investigated as a cathode material for aqueous zinc-metal batteries. It is identified that the Ti-substitution has a significant effect on improving its rate capability and cycling stability. As a result, the optimal Na 0.44 Mn 0.78 Ti 0.22 O 2 (NMTO-0.22) material exhibits a reversible capacity of 109.6 mAh/g at 1.0 A g−1, and 71% of the initial capacity can be retained after 2400 cycles. Such performance can be attributed to the enhanced insertion mechanisms in the tunnel structure, as verified by the post-mortem spectroscopic and microscopic techniques. Density functional theory (DFT) calculations enclose that the average charge density in Mn 3d orbits near the Fermi level and Mn participation in redox reaction are improved after Ti-substitution, supporting the facilitated electrochemical kinetics of NMTO. This work demonstrates that the Ti-substituted Na 0.44 MnO 2 is a promising cathode material for aqueous zinc-metal batteries, and provides a fundamental understanding on the charge storage mechanisms. [ABSTRACT FROM AUTHOR]