DNA-Assisted Synthesis of Defect-Rich MnO₂ Cathodes for High-Rate and Long-Life Aqueous Zinc-Ion Batteries

Designing MnO₂ cathodes capable of operating at high rates without structural degradation remains a major challenge for aqueous zinc-ion batteries. In this work, we introduce a simple DNA-assisted hydrothermal synthesis strategy in which deoxyribonucleic acid (DNA) acts as a molecular precursor that generates phosphate- and nitrogen-containing groups coordinate with Mn ions during nucleation. This coordination yields defect-rich, loosely stacked δ-MnO₂ nanoflakes with slightly expanded interlayer spacing, enriched Mn^{3 +} sites and oxygen-related defects which enable rapid Zn²⁺ insertion/extraction without structural collapse. Comprehensive FTIR, XPS, XRD, and N₂ sorption analyses confirm increased Mn^{3 +} content, defect-rich local environments, and enhanced surface area and mesoporosity, which collectively facilitate fast charge storage kinetics and accessible redox centers. Benefiting from these synergistic features, the DNA-MnO₂ cathode delivers a high capacity of 293.3 mAh g^-1 at 0.2 A g^-1 and maintains 121.6 mAh g^-1 at 10 A g^-1. It also exhibits excellent cycling stability, retaining 86.5% capacity after 500 cycles at 2 A g^-1 and delivering 53.8 mAh g^-1 after 10 000 cycles at 10 A g^-1 with Coulombic efficiency above 99.8%.