Dual-cations modulating δ-MnO₂ as a high-performance cathode material for aqueous zinc-ion batteries

δ-MnO₂ has been widely recognized as a promising cathode material for aqueous zinc-ion batteries (AZIBs) owing to its high theoretical specific capacity, low cost and environmental benignity. Nevertheless, its practical application is constrained by low electronic conductivity and structural instability. Herein, a class of Fe&Co dual-cations doping δ-MnO₂ (FCMO) is synthesized via a facile hydrothermal route, which effectively modulates the crystal structure and electrochemical properties of δ-MnO₂. The nanoflower-like morphology of FCMO shortens the ion diffusion path and facilitates ion transport. Specifically, this dual-cations doping not only introduces oxygen vacancies to further promote electronic conductivity and structural stability, but also significantly expands the interlayer spacing to enhance Zn²⁺ diffusion kinetics. Benefiting from these structural advantages, FCMO delivers a high specific capacity of 319.9 mAh·g^-1 at a current density of 0.5 A·g^-1 and an excellent rate performance of 100.1 mAh·g^-1 at 2 A·g^-1. Moreover, it exhibits an outstanding cycling stability, retaining 94.7% of its capacity after 1000 cycles at 1 A·g^-1. This demonstrates that Fe&Co dual-cations doping strategy is an effective way to enhance the electrochemical performance of δ-MnO₂, offering a valuable insight for the design and development of high-performance AZIBs.