Ultra-stable MnO2 cathode enabled by Fe doping and carbon nanotubes scaffolding for long-cycling zinc-ion batteries

Abstract

Aqueous zinc-ion batteries face critical challenges with MnO₂ cathodes due to their poor electronic conductivity and structural instability. This work addresses these issues by using Fe³⁺ doping and CNTs hybridisation to modify the atomic coordination and interfacial charge transfer synergistically. The incorporated Fe³⁺ ions induce lattice strain and redistribute electron density in the MnO₂, which substantially enhances electron mobility and reduces reaction resistance during Zn²⁺ intercalation. Meanwhile, the interwoven CNT network establishes rapid electron transport channels and physically constrains the MnO₂ particles, preventing structural degradation. The optimized Fe-MnO₂/C composite exhibits a high specific capacity of 340 mA h g⁻¹ at 0.1 A g⁻¹, and demonstrates exceptional rate capability. Notably, it maintains 97.9 mA h g⁻¹ at 2 A g⁻¹ over 1000 cycles with 89 % retention, 2.5 times higher than undoped MnO₂. This dual-modification strategy offers a practical approach for developing high-performance cathodes toward zinc-ion batteries.