Order-disorder transition in nano-rutile TiO 2 anodes: a high capacity low-volume change Li-ion battery material

• Published in: Nanoscale 2019-06, Vol.11 (25), p.12347-12357
• Main Authors: Christensen, Christian Kolle, Mamakhel, Mohammad Aref Hasen, Balakrishna, Ananya Renuka, Iversen, Bo Brummerstedt, Chiang, Yet-Ming, Ravnsbæk, Dorthe Bomholdt
• Format: Article
• Language: English
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/C9NR01228A

Nano-sized particles of rutile TiO is a promising material for cheap high-capacity anodes for Li-ion batteries. It is well-known that rutile undergoes an irreversible order-disorder transition upon deep discharge. However, in the disordered state, the Li TiO material retains a high reversible ion-storage capacity of >200 mA h g . Despite the promising properties of the material, the structural transition and evolution during the repeated battery operation has so far been studied only by diffraction-based methods, which only provide insight into the part that retains some long-range order. Here, we utilize a combination of ex situ and operando total scattering with pair distribution function analysis and transmission electron microscopy to investigate the atomic-scale structures of the disordered Li TiO forming upon the discharge of nano-rutile TiO as well as to elucidate the phase behavior in the material during the repeated charge-discharge process. Our investigation reveals that nano-rutile upon Li-intercalation transforms into a composite of ∼5 nm domains of a layered Li TiO α-NaFeO -type structure with ∼1 nm Li TiO grain boundaries with a columbite-like structural motif. During repeated charge-discharge cycling, the structure of this composite is retained and stores Li through a complete solid-solution transition with a remarkably small volume change of only 1 vol%.