Bundle-like α′-NaV₂O₅ mesocrystals: From synthesis, growth mechanism to analysis of Na-ion intercalation/deintercalation abilities

Bundle-like α′-NaV₂O₅ mesocrystals were synthesized successfully by a two-step hydrothermal method. Observations using electron microscopy revealed that the obtained NaV₂O₅ mesocrystals were composed of nanobelts with the preferential growth direction of [010]. The precise crystal structure was further confirmed by Rietveld refinement and Raman spectroscopy. Based on analysis of crystal structure and microscopy, a reaction and growth mechanism, hydrolysis-condensation (oxolation and olation)-ion exchange-self-assembly, was proposed and described in detail. Furthermore, electrochemical measurements were used to analyze the Na-ions intercalation/deintercalation abilities in NaV₂O₅, and indicated that Na-ions were difficult to extract. Importantly, the DFT theoretical calculation results, which showed that the migration energy of Na-ions was so huge that migration of Na-ions was quite difficult, can explain and support well the results of the electrochemical measurements.