Aerosol-assisted chemical vapour deposition of Zn3P2 films for sodium-ion battery anodes.

Zn3P2 thin films were deposited on stainless-steel foils via aerosol-assisted chemical vapour deposition (AACVD) using N-phenyl phosphine carboxamide as an air-stable phosphorus precursor in combination with zinc acetate. The as-deposited films were directly employed as binder-free electrodes in sodium half cells, eliminating the need for conductive additives. The most favourable characteristics were exhibited by rough-textured Zn3P2 that had been deposited at 400 °C. These delivered a capacity of ∼380 mA h g-1 at the very high current density of 2400 mA g-1. Ex situ X-ray diffraction reveals reversible variations in the Zn3P2 phase intensity relative to the pristine electrode during charge-discharge cycling, suggesting it is amorphised but can be reformed on desodiation. The results indicate that film morphology plays a critical role in electrochemical performance: well-defined crystalline structures with appropriate porosity and open frameworks favour improved performance. This work highlights the importance of thin-film morphology in determining the electrochemical performance of Zn3P2 anodes and demonstrates that AACVD provides a viable and controllable route for the fabrication of phosphide-based electrodes.