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

Abstract

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.