Operando Raman and DFT Analysis of (De)lithiation in Fast-Charging, Shear-Phase H-Nb₂O₅

Niobium-based compoundswith Wadsley-Roth crystallographicshear structures show promise as fast lithium storage materials inmicrometer sizes without the need for nanostructure engineering. However,the lithium storage mechanism underlying their unique electrochemicalproperties has yet to be understood. Herein, we characterized theevolution of vibration bands in operando Raman spectraof the representative shear phase, H-Nb2O5,during lithiation in order to correlate the lithiation-induced structuralvariations of H-Nb2O5 with the electrochemicalproperties. Complemented by DFT calculations, the lithium storagemechanism was unraveled, including the preference for adsorption sites,the resultant electronic structure, and specific pathways for lithiumtransport. This work provides insight into the lithium storage mechanismin shear structure Nb2O5, which is believedto be useful for knowledge-based design of niobium-based compoundsas high-rate lithium storage materials.