Mn-MOF-derived litchi-like MnO/MnS@C heterojunction cathode material for high-performance aqueous zinc-ion batteries

Abstract

Manganese-based materials are commonly employed as cathodes in rechargeable aqueous zinc-ion batteries (AZIBs) due to their high theoretical capacity, minimal toxicity and low cost. However, poor conductivity, sluggish charge diffusion kinetics, and unfavorable lattice distortion caused by Jahn-Teller effects are still hindering their practical application. Herein, a litchi-like MnO/MnS heterojunction composite cathode material (MnO/MnS@C) was prepared through carbonization-sulfidation derived from spherical manganese-based metal-organic framework (Mn-MOF). The litchi-like morphology of MnO/MnS originates from hydrothermal sulfidation etching, which facilitates the formation of numerous electrochemically active heterointerfaces. Benefiting from the synergistic effects of built-in electric fields in heterojunctions and abundant ionic defects, the MnO/MnS@C demonstrates significantly improved conductivity and charge transfer kinetics. Furthermore, the conformal carbon layer ensures the structural stability of the MnO/MnS@C heterojunction. As a result, the as-prepared MnO/MnS@C cathode for AZIBs delivers a specific capacity of 238 mAh g⁻¹ at 0.3 A g⁻¹, with 175 mAh g⁻¹ at 2.0 A g⁻¹, and the capacity retention rate is 82.7 % after 4000 cycles. Ex-situ characterization reveals the charge storage mechanism of MnO/MnS@C, providing valuable insights for developing high-performance zinc-ion battery cathode materials.