Phase-engineered 1T′/2H-MoS2 heterophase junctions for high-performance aqueous zinc-ion batteries

Abstract

The development of high-performance aqueous zinc-ion battery (AZIB) cathodes requires materials that combine efficient ion transport with structural stability. While conventional layered transition metal dichalcogenides (TMDs), represented by two-dimensional (2D) molybdenum disulfide (MoS₂), possess ideal diffusion channels, their semiconducting 2H phase suffers from limited interlayer spacing, poor hydrophilicity, and low electrical conductivity, hindering efficient Zn²⁺ storage. Here, we report a one-step synthesis of 2D 1T′/2H-MoS₂ heterophase junctions via a thermal evaporation strategy, leveraging potassium-assisted phase engineering to stabilize the metastable 1T′ phase. The hybrid-phase structure expands the layer spacing (from 0.62 to 0.80 nm), enhances the electronic conductivity, facilitates ion transport, maximizes active sites, and improves hydrophilicity, enabling superior Zn²⁺ diffusion kinetics. Electrochemical tests demonstrate that the 1T′/2H-MoS₂ cathode delivers a high specific capacity (150 mAh g⁻¹ at 1 A g⁻¹), excellent rate capability (120 mAh g⁻¹ at 2.0 A g⁻¹), and exceptional cycling stability (86.4% capacity retention after 2000 cycles). Ex situ spectroscopic and microscopic analyses reveal a reversible Zn²⁺ insertion/extraction mechanism accompanied by dynamic phase transitions and lattice breathing. Density functional theory (DFT) calculations further confirm that the 1T′ phase significantly enhances Zn²⁺ adsorption and reduces diffusion barriers. This work provides a novel strategy for designing phase-engineered TMDs as high-performance AZIB cathodes, paving the way for next-generation energy storage systems.