Aqueous rechargeable zinc‐metal‐based batteries are an attractive alternative to lithium‐ion batteries for grid‐scale energy‐storage systems because of their high specific capacity, low cost, eco‐friendliness, and nonflammability. However, uncontrollable zinc dendrite growth limits the cycle life by piercing the separator, resulting in low zinc utilization in both alkaline and mild/neutral electrolytes. Herein, a polyacrylonitrile coating layer on a zinc anode produced by a simple drop coating approach to address the dendrite issue is reported. The coating layer not only improves the hydrophilicity of the zinc anode but also regulates zinc‐ion transport, consequently facilitating the uniform deposition of zinc ions to avoid dendrite formation. A symmetrical cell with the polymer‐coating‐layer‐modified Zn anode displays dendrite‐free plating/stripping with a long cycle lifespan (>1100 h), much better than that of the bare Zn anode. The modified zinc anode coupled with a Mn‐doped V2O5 cathode forms a stable rechargeable full battery. This method is a facile and feasible way to solve the zinc dendrite problem for rechargeable aqueous zinc‐metal batteries, providing a solid basis for application of aqueous rechargeable Zn batteries.

Rechargeable sodium–iodine (Na–I2) batteries are attracting growing attention for grid‐scale energy storage due to their abundant resources, low cost, environmental friendliness, high theoretical capacity (211 mAh g−1), and excellent electrochemical reversibility. Nevertheless, the practical application of Na–I2 batteries is severely hindered by their poor cycle stability owing to the serious dissolution of polyiodide in the electrolyte during charge/discharge processes. Herein, the atomic modulation of metal–bis(dihydroxy) species in a fully conjugated phthalocyanine copper metal–organic framework (MOF) for suppression of polyiodide dissolution toward long‐time cycling Na–I2 batteries is demonstrated. The Fe2[(2,3,9,10,16,17,23,24‐octahydroxy phthalocyaninato)Cu] MOF composited with I2 (Fe2–O8–PcCu/I2) serves as a cathode for a Na–I2 battery exhibiting a stable specific capacity of 150 mAh g−1 after 3200 cycles and outperforming the state‐of‐the‐art cathodes for Na–I2 batteries. Operando spectroelectrochemical and electrochemical kinetics analyses together with density functional theory calculations reveal that the square planar iron–bis(dihydroxy) (Fe–O4) species in Fe2–O8–PcCu are responsible for the binding of polyiodide to restrain its dissolution into electrolyte. Besides the monovalent Na–I2 batteries in organic electrolytes, the Fe2–O8–PcCu/I2 cathode also operates stably in other metal–I2 batteries like aqueous multivalent Zn–I2 batteries. Thus, this work offers a new strategy for designing stable cathode materials toward high‐performance metal–iodine batteries.

Among the negative electrode materials for potassium ion batteries, carbon is very promising because of its low cost and environmental benignity. However, the relatively low storage capacity and sluggish kinetics still hinder its practical application. Herein, a large scalable sulfur/nitrogen dual‐doped hard carbon is prepared via a facile pyrolysis process with low‐cost sulfur and polyacrylonitrile as precursors. The dual‐doped hard carbon exhibits hierarchical structure, abundant defects, and functional groups. The material delivers a high reversible potassium storage capacity and excellent rate performance. In particular, a high reversible capacity of 213.7 and 144.9 mA h g−1 can be retained over 500 cycles at 0.1 A g−1 and 1200 cycles at 3 A g−1, respectively, demonstrating remarkable cycle stability at both low and high rates, superior to the other carbon materials reported for potassium storage, to the best of the authors' knowledge. Structure and kinetics studies suggest that the dual‐doping enhances the potassium diffusion and storage, profiting from the formation of a hierarchical structure, introduction of defects, and generation of increased graphitic and pyridinic N sites. This study demonstrates that a facile and scalable pyrolysis strategy is effective to realize hierarchical structure design and heteroatom doping of carbon, to achieve excellent potassium storage performance.

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