Exploring the Nb-Ti-W-O System for Use as Li-Ion Battery Anodes

Abstract

While much attention in recent years has been given to high performance Li-ion batteries for electrical vehicles, other applications such as medical devices require a unique set of properties that demand a different set of material considerations such as long lifetimes and extremely high safety. Anodes for such batteries must be carefully selected to properly achieve these goals. The most commonly industrially utilized anode material, graphite, is not suitable for medical applications due to particle fracture and Li dendrite growth at high rates. Currently utilized medical device anode materials obtain this high performance by sacrificing energy density.Herein a new set of Nb based materials for use as anodes are presented that do not need to make such a sacrifice as they display high longevity along with high energy densities. The Nb-Ti-W pseudoternary features many promising single-phase compositions that could be used as anodes for such devices. These compositions derive from crystal structures that are found on both the Nb2O5-WO3 and Nb2O5-TiO2 pseudobinaries1, though they posses a more diverse range of chemical compositions. These compositions feature high performance discharge capacities of up to 300 mAh/g. Some materials also display robust capacity retentions of up to 98% after 10 cycles. The materials were also tested at 37 °C to simulate operation within the human body. At these temperatures, improvements were found in electrochemical performance for nearly all compositions, notably demonstrating a large improvement in capacity retention regardless of crystal structure. References (1) Rehman, S.; Sieffert, J. M.; Lang, C. J.; McCalla, E. NbyW1-yOz and NbxTi1-xOz pseudobinaries as anodes for Li-ion batteries. Electrochimica Acta 2023, 439. DOI: 10.1016/j.electacta.2022.141665.