Na0.4MnO2/MXene nanocomposites as cathodes for high-performance aqueous zinc-ion batteries

Abstract

The distinctive configuration of MnO₂ renders it an exceptionally promising candidate for cathode materials for aqueous zinc-ion batteries (ZIBs). However, its practical utilization is constrained by the sluggish diffusion kinetics of Zn²⁺ and the capacity degradation resulting from lattice distortions occurring during charge and discharge cycles. To address these challenges, Na_0.4MnO₂@MXene with a typical 2 × 4 tunnel structure has been successfully synthesized by a simple hydrothermal method in the presence of 5 M NaCl. The nanorods are about 56 nm in diameter. The zinc-ion batteries (ZIBs) with Na_0.4MnO₂@MXene displays a specific capacity of 324.6 mA h g⁻¹ at 0.2 A g⁻¹, and have a high reversible capacity of 153.8 mA h g⁻¹ after 1000 charge–discharge cycles at 2 A g⁻¹ with a capacity retention of 91.4%. The unique morphology endows abundant electrochemical active sites and facile ion diffusion kinetics, that contribute to the high specific capacity and stability. The Na_0.4MnO₂@MXene with a 2 × 4 tunnel structure is a promising candidate as an electrode material for ZIBs.