Auxiliary thermodynamic analysis support capturing the differences in nanostructured FeVO4·nH2O electrodes between lithium and sodium ions storage mechanism

A fundamental understanding of ion charge storage mechanisms in nanostructured electrodes is essential to improve the performance of batteries or devices for rechargeable energy storage systems. Herein, we systematically discuss the lithium and sodium ions storage mechanisms of FeVO4·nH2O nanowires electrodes from the experimentally evaluated extent of conversion reaction and the thermodynamic modeling of the occurrence of ion storage at heterogeneous junctions. Experimental characterizations demonstrate that FeVO4·nH2O nanowires exhibit a higher degree of conversion during the lithium ions storage process than when accommodating sodium ions. Density functional theory calculation reveals that this discrepancy is due to differences in ion-binding sites and diffusion paths between the lithium and sodium ions in FeVO4·nH2O nanowires. Thermodynamics analysis of the job-sharing mechanism-based heterogeneous storage model further supports the different extent of conversion for lithium and sodium ions storage. The approach indicated in this work enables a promising path toward the electrochemical reaction mechanism analysis of energy storage materials from the auxiliary thermodynamics perspective and can provide valuable guidance for advanced high-energy-density electrodes.