3D Printing of Layered Vanadium Disulfide for Zinc Ion Batteries

Aqueous zinc ion batteries are attractive energy storage devices for wearable electronics, owing to their safety and low cost. Among cathode materials, layered vanadium disulfide (VS2) has demonstrated good charge storage capability, as a result of its metallic character and large interlayer spacing. However, VS2 electrodes present fixed shapes and aspect ratios, and they are processed using toxic solvents, which hinders their integration in wearables. It is thus necessary to develop manufacturing methods that can meet the demand for shape customization and do not rely on toxic solvents. Here, we propose a flower-like VS2 architectures using a simple hydrothermal process to formulate an ink for extrusion 3D Printing (Direct Ink Writing). The 3D printing technique enables the fabrication of VS2 electrodes with porous micron-sized struts, high-mass loading of ~ 45 mg cm-2 and good conductivity. Using the 3D printed VS2 cathodes, zinc-ion microbatteries were assembled, achieving a capacity of ~ 1.98 mAh cm-2 and demonstrating a capacity retention of over 55% after 150 cycles. The choice of the electrolyte and processing of the cathode ensured good stability against dissolution, a no-torious challenge for VS2 in aqueous environment. In particular, the dissolution of VS2 cathodes for ZIBs was here prevented by the use of a water-in-salt electrolyte (WISE), enabling a long cycling life with higher capacity. This works paves the way towards form-free manufacturing of aqueous batteries which can be extended to different nanomaterials.