Defect-Driven Niobium Oxide Electrode for Lithium-Ion Batteries

The development and innovation of new electrode materials is needed for the next generation of electrochemical energy storage systems (EES). Lithium-ion batteries (LIB) are the leading technology in EES, however, they are plagued with several limitations including safety and stability. Metal oxide electrodes could provide a safer battery while maintaining high reversible capacity. When compared to the commonly used graphite, metal oxides operate at voltages above that of Li plating for safe operation. In addition, nanostructured metal oxides could enhance the performance of the battery by facilitating fast electron and ion transport. Traditionally, intercalation compounds of well-ordered close-packed oxides have been prized because of the general consensus that well-ordered structures having little or no intermixing between Li and transition metal sublattice are required to achieving high capacity with good stability. Consequently, disordered materials have received limited attention and have been less studied. Nevertheless, in recent years evidence has shown that transition metal oxides which have structural defects (e.g., vacancies and interstitials) at cation sites with local disorder have the potential to offer higher capacity and better stability compared to ordered oxides. In this talk, we report our integrated experimental and computational study of a nanostructured amorphous niobium oxide electrode for lithium ion battery. An irreversible phase transformation from amorphous to crystalline phase in niobium oxide electrode is observed during the first discharging process. The newly formed crystalline niobium oxide electrode exhibits high capacity, superb rate capability and good cycle life. The electrochemical charge storage mechanisms of the new electrode will be discussed.