Bayan Baatiyah

Aqueous zinc-ion batteries (ZIBs) are emerging as safe, low-cost, and sustainable alternatives for large-scale energy storage. However, the widespread application of manganese dioxide (MnO₂) cathodes remains limited by their inherently poor electronic conductivity, slow Zn²⁺ diffusion, and gradual structural degradation. In this work, we demonstrate a simple, room temperature electrodeposition method to fabricate cobalt-doped MnO₂ (Co–MnO₂) nanowire cathodes directly on conductive graphite substrates. This scalable process enables precise control over composition and morphology, producing interconnected amorphous nanowires with abundant active sites and open diffusion channels.

Comprehensive structural and surface characterization using X-ray diffraction, field-emission scanning electron microscopy, and X-ray photoelectron spectroscopy confirms that cobalt incorporation generates oxygen vacancies, stabilizes mixed Mn³⁺/Mn⁴⁺ valence states, and induces partial amorphization. These synergistic effects markedly enhance Zn²⁺ transport and electronic conductivity, resulting in lower charge-transfer resistance and improved redox kinetics.

Electrochemical testing reveals that the Co–MnO₂ cathode delivers an initial capacity of 372 mAh g⁻¹ at 0.5 A g⁻¹ and maintains 246.4 mAh g⁻¹ at 1 A g⁻¹, while retaining approximately 84% of its capacity after 600 cycles at 1 A g⁻¹. These values surpass those of pristine MnO₂ and many MnO₂-based cathodes reported in recent literature. The outstanding rate capability and long-term stability are attributed to the combined benefits of cobalt-induced defect engineering and the high-surface-area nanowire architecture.

This study highlights cobalt doping via electrodeposition as an effective and industry-compatible route to engineer defect-rich MnO₂ cathodes. The results provide actionable insights for designing next-generation aqueous ZIBs and other sustainable energy-storage systems aligned with the global transition toward clean and reliable energy.