Nanodiamond‐Directed Oriented Growth of MnO ₂ Cathodes for Ultrastable Aqueous Zinc‐Ion Batteries

Manganese‐based cathodes are promising for aqueous zinc‐ion batteries because of their low‐cost, high capacity, and environmental benignity, however, their performance is hampered by sluggish charge transport and Mn dissolution–induced structural degradation. Herein, a functionalized nanodiamond (ND) mediated nucleation strategy is developed to construct ND@MnO 2 heterostructures that direct MnO 2 crystallization and stabilize its framework. First‐principles calculations show that the polar ND surface redistributes interfacial charge, strengthening Zn adsorption from ‐1.16 eV on pristine MnO 2 to ‐3.92 eV on ND@MnO 2 , suggesting an enhanced interfacial affinity toward zinc species and improved zinc accommodation, which is consistent with suppressed Mn dissolution. ND@MnO 2 exhibits an increased density of states and a narrowed bandgap near the Fermi level, indicating enhanced intrinsic conductivity. Consequently, ND@MnO 2 enables accelerated Zn 2+ diffusion kinetics, higher pseudocapacitive contribution, and lower charge‐transfer resistance, delivering nearly twice the reversible capacity of MnO 2 and maintaining 90% capacity retention after 2000 cycles at 1 A g −1 . This low‐cost and scalable interfacial engineering strategy effectively overcomes the conduction bottleneck and stability issues of Mn‐based cathodes, paving the way for high‐rate, durable aqueous zinc‐ion batteries (ZIBs).