Tailoring hierarchical MnO2 nanostructures on self-supporting cathodes for high-mass-loading zinc-ion batteries

Abstract

Aqueous zinc-ion batteries (AZIBs) with MnO₂ cathodes have promising application prospects; however, their performance is hindered by their low efficiency and insufficient life. By leveraging the nanomicellar properties of cetyltrimethylammonium bromide (CTAB), a hierarchical δ-MnO₂ with 2D/3D structure was directionally grown on a modified carbon cloth (CC) collector for realizing high-mass-loading AZIBs. Experimental results reveal the synergistic effects of micro/nano hierarchically structured MnO₂–CC heterointerfaces in accelerating the electron migration and transfer rate of Zn²⁺/H⁺. Functioning as a conductive skeleton and flexible substrate, CC efficiently improves the reaction kinetics and buffers the interfacial stress resulting from the structural evolution of MnO₂ during the long-term electrode reaction. This phenomenon is investigated using advanced characterisation techniques, including X-ray absorption fine structure spectroscopy, Kelvin probe force microscopy, and theoretical simulations. The fabricated electrode exhibits superior electrochemical properties, such as high capacity (409.6 mA h g⁻¹ at 0.1 A g⁻¹) and reliable cycling performance (with 86.6% capacity retention after 2000 cycles at 1.0 A g⁻¹). Even at a high mass loading of 6.0 mg cm⁻², the battery retains 81.8% of its original capacity after 1300 cycles. The proposed interface engineering strategy provides valuable insights into realising high-loading and long-life AZIBs.