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Aqueous zinc (Zn) battery with remarkable advantages of high safety, low cost, and high reversibility is highly applauded in next‐generation low‐speed electric vehicles and large‐scale energy storage applications. However, Zn anode suffers from a series of unfavorable reactions, hindering its progress toward industrialization. Herein, a functionalized hydrogel film is designed using polydopamine and polyacrylamide crosslinking (PDAM) as the Zn protective layer to stabilize the Zn anode. Benefiting from the strong interaction of Zn2+ with PDAM, the primary solvation shell of Zn2+ is regulated by PDAM into the form of PDAM–Zn2+‐5H2O. This remodeling prevents Zn dendrite growth and inhibits water‐induced side reactions. As a result, the Zn–MnO2 battery using PDAM‐coated Zn anode exhibits excellent cycling stability, demonstrating over 1150 cycles at an areal capacity of 5 mAh cm−2 with an average Coulombic efficiency (CE) of 96.5%. For a scaled‐up PDAM@Zn–MnO2 pouch cell with a capacity of 80 mAh, stable cycling of over 200 cycles with an average CE of 91.9% is achieved. The superior Zn–MnO2 battery enabled by the functionalized hydrogel protective film enlightens an arena toward next‐generation energy storage applications. [ABSTRACT FROM AUTHOR]

The commercialization of electrolytic MnO2–Zn batteries is highly applauded owing to the advantages of cost‐effectiveness, high safety, high energy density, and durable working performance. However, due to the low reversibility of the cathode MnO2/Mn2+ chemistry at high areal capacities and the severe Zn anode corrosion, the practical application of MnO2–Zn batteries is hampered by inadequate lifespan. Leveraging the full advantage of an iodine redox mediator, here we design a highly rechargeable electrolytic MnO2–Zn battery with a high areal capacity. The MnO2–Zn battery coupled with an iodine mediator in a mild electrolyte shows a high discharge voltage of 1.85 V and a robust areal capacity of 10 mAh cm−2 under a substantial discharge current density of 160 mA cm−2. The MnO2/I2–Zn battery with an areal capacity of 10 mAh cm−2 exhibits prolonged stability of over 950 cycles under a high‐capacity retention of ~94%. The scaled‐up MnO2/I2–Zn battery reveals a stable cycle life under a cell capacity of ~600 mAh. Moreover, our constructed MnO2/I2–Zn battery demonstrates a practical energy density of ~37 Wh kg−1 and a competitive energy cost of <18 US$ kWh−1 by taking into account the cathode, anode, and electrolyte. The MnO2/I2–Zn battery, with its remarkable reversibility and reasonable energy density, enlightens a new arena of large‐scale energy storage devices. [ABSTRACT FROM AUTHOR]

The zinc-iodine aqueous battery is a promising energy storage device, but the conventional two-electron reaction potential and energy density of the iodine cathode are far from meeting practical application requirements. Given that iodine is rich in redox reactions, activating the high-valence iodine cathode reaction has become a promising research direction for developing high-voltage zinc-iodine batteries. In this work, by designing a multifunctional electrolyte additive trimethylamine hydrochloride (TAH), a stable high-valence iodine cathode in four-electron-transfer I-/I2/I+ reactions with a high theoretical specific capacity is achieved through a unique amine group, Cl bidentate coordination structure of (TA)ICl. Characterization techniques such as synchrotron radiation, in-situ Raman spectra, and DFT calculations are used to verify the mechanism of the stable bidentate structure. This electrolyte additive stabilizes the zinc anode by promoting the desolvation process and shielding mechanism, enabling the zinc anode to cycle steadily at a maximum areal capacity of 57 mAh cm-2 with 97% zinc utilization rate. Finally, the four-electron-transfer aqueous Zn-I2 full cell achieves 5000 stable cycles at an N/P ratio of 2.5. The unique bidentate coordination structure contributes to the further development of high-valence and high capacity aqueous zinc-iodine batteries., (© 2024 Wiley‐VCH GmbH.)

An aqueous electrolytic MnO 2 -Zn battery with eye-catching Mn 2+ /MnO 2 cathode chemistry has been attracting immense interest for next-generation energy storage devices due to its irreplaceable advantages. However, the limited MnO 2 conductivity restricts its long service life at high areal capacities. Here, we report a high-performance electrolytic MnO 2 -Zn battery via a bromine redox mediator, to enhance its electrochemical performance. The MnO 2 /Br 2 -Zn battery displays a high discharge voltage of 1.98 V with a capacity of ∼5.8 mAh cm -2 . It also shows an excellent rate performance of 20 C with a long-term stability of over 600 cycles. Furthermore, the scaled-up MnO 2 /Br 2 -Zn battery with a capacity of ∼950 mAh exhibits a stable 100 cycles with a practical cell energy density of ∼32.4 Wh kg -1 and an attractively low energy cost of below 15 US$ kWh -1 . The design approach can be generalized to other electrodes and battery systems, thus opening up new possibilities for large-scale energy storage.