3D-structured bifunctional MXene paper electrode (3D-BMPE), which has distinctive material properties, was fabricated to protect Al deposition/dissolution reactions with improved redox kinetics.

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Zinc metal anodes (ZMA) have high theoretical capacities (820 mAh g−1 and 5855 mAh cm−3) and redox potential (−0.76 V vs. standard hydrogen electrode), similar to the electrochemical voltage window of the hydrogen evolution reaction (HER) in a mild acidic electrolyte system, facilitating aqueous zinc batteries competitive in next‐generation energy storage devices. However, the HER and byproduct formation effectuated by water‐splitting deteriorate the electrochemical performance of ZMA, limiting their application. In this study, a key factor in promoting the HER in carbon‐based electrode materials (CEMs), which can provide a larger active surface area and guide uniform zinc metal deposition, was investigated using a series of three‐dimensional structured templating carbon electrodes (3D‐TCEs) with different local graphitic orderings, pore structures, and surface properties. The ultramicropores of CEMs are the determining critical factors in initiating HER and clogging active surfaces by Zn(OH)2 byproduct formation, through a systematic comparative study based on the 3D‐TCE series samples. When the 3D‐TCEs had a proper graphitic structure with few ultramicropores, they showed highly stable cycling performances over 2000 cycles with average Coulombic efficiencies of ≥99%. These results suggest that a well‐designed CEM can lead to high‐performance ZMA in aqueous zinc batteries.

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Extensive research has been conducted in order to enhance the capacities of Li-ion batteries (LIBs). However, there is limited research on binders which are one of the main electrode components that contribute to the long life cycle of LIBs. Improving the binder properties enhances both long-term cycling performance and battery life. In this study, amorphous polyhydroxyalkanoate (aPHA), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), with a 4-hydroxybutyric acid content of approximately 47%, was used as a novel eco-friendly binder material. aPHA is an affinity polymer material synthesized by microorganisms and is suitable as a binder because of its electrochemical and thermal stability over the operating voltage and temperature ranges of LIBs. aPHA allowed strong adhesion between the active material and the current collector and maintained the structural stability of the electrode even after long-term cycling owing to its elastic properties. In addition, the high wettability of the aPHA binder toward the electrolyte reduced the resistance of the electrode, providing a shortened diffusion path for Li ions. As a result, aPHA exhibited a superior capacity over the commercially available polyvinylidene fluoride binder and displayed capacity retention with a high Coulombic efficiency (CE) of over 94% for 100 cycles. The PHA content was reduced from 10% to 5% by weight relative to that of the electrode, while the active material content was increased. The use of the aPHA binder increased the capacity and capacity retention with a CE of 94.1% over 100 cycles, indicating its potential as a next-generation eco-friendly binder for LIBs.