B,N-Codoped Carbon Nanotube Array Anchored with MnO₂ Nanosheets as Flexible Cathodes for Aqueous Zinc-Ion Batteries

For rechargeable aqueous zinc-ion batteries (ZIBs), the hierarchical design of nanocomposites comprising electrochemically active materials and carbon materials with novel structures holds great promise in addressing the issue of electrical conductivity, structural stability in the electrode materials during electrochemical cycling. Herein, a novel flexible electrode material by anchoring MnO₂ nanosheets on B,N-codoped carbon nanotubes array (BNCNTs) grown on carbon cloth (BNCNTs@MnO₂) is fabricated by in situ pyrolysis and hydrothermal growth strategies. The in situ generated BNCNTs are robustly bonded on the surface of carbon fibers within the carbon cloth, in which the hierarchical carbon substrate is conducive both to electron transport and ion diffusion, improving the stability and durability of the cathode. Importantly, the BNCNTs offer more active sites for the hydrothermal growth of MnO₂, ensuring uniform distribution and strong affinity. Electrochemical tests reveal that BNCNTs@MnO₂ delivers a high specific capacity of 310.7 mAh g⁻¹ at 0.1 A g⁻¹, along with excellent rate capability and outstanding cycling stability with 79.7% capacity retention after 8000 cycles at 3 A g⁻¹. This work provides inspiration for developing flexible composite electrodes of aqueous ZIBs with high-performance through the creation of hierarchical substrates and surface modification.