Polymorphs of NbO Compound and Their Electrical Energy Storage Applications.

Niobium pentoxide (NbO), as an important dielectric and semiconductor material, has numerous crystal polymorphs, higher chemical stability than water and oxygen, and a higher melt point than most metal oxides. NbO materials have been extensively studied in electrochemistry, lithium batteries, catalysts, ionic liquid gating, and microelectronics. NbO polymorphs provide a model system for studying structure-property relationships. For example, the T-NbO polymorph has two-dimensional layers with very low steric hindrance, allowing for rapid Li-ion migration. With the ever-increasing energy crisis, the excellent electrical properties of NbO polymorphs have made them a research hotspot for potential applications in lithium-ion batteries (LIBs) and supercapacitors (SCs). The basic properties, crystal structures, synthesis methods, and applications of NbO polymorphs are reviewed in this article. Future research directions related to this material are also briefly discussed.