Improving the stability of MnO₂ cathode via conjugated π-systems with electron-withdrawing groups in aqueous zinc-ion batteries

Manganese dioxide (MnO₂) has emerged as a promising cathode material for aqueous zinc-ion batteries (AZIBs) owing to its cost-effectiveness and high theoretical capacity, garnering significant research interest. However, the intrinsically low electronic conductivity and sluggish ion diffusion kinetics of MnO₂ induce strong Coulombic interactions on surface, which trigger severe structural distortion of the material during charge-discharge process and inadequate cycling stability. Herein, the strategy is proposed to enhance the stability of manganese dioxide MnO₂ by introducing 3,6-dioxo-3,6-dihydropyridine-2,4,5-tricarboxylic acid (DDTA)—a functional molecule featuring both conjugated π-bonds and electron-withdrawing groups. The synergistic effect of these moieties effectively lowers the lowest unoccupied molecular orbital (LUMO) while elevating the highest occupied molecular orbital (HOMO), which suppresses interfacial ion aggregation on the cathode, thereby mitigating Coulombic interactions between cations and MnO₂ cathode. Consequently, the DDTA-MnO₂ cathode exhibits superior high-rate long-term cycling stability (retaining approximately 70% capacity over 16,000 cycles at 10 A g−1), alongside a high specific capacity (401.3 mAh g−1 at 0.1 A g−1) and exceptional rate capability (209.1 mAh g−1 at 10 A g−1). Overall, this work presents a promising avenue for designing highly stable cathode materials for advanced aqueous zinc-ion batteries.