We report an electrochemically driven transformation of amorphous TiO 2 nanotubes for Li-ion battery anodes into a face-centered-cubic crystalline phase that self-improves as the cycling proceeds. The intercalation/deintercalation processes of Li ions in the electrochemically grown TiO 2 nanotubes were studied by synchrotron X-ray diffraction and absorption spectroscopies along with advanced computational methods. These techniques confirm spontaneous development of a long-range order in amorphous TiO 2 in the presence of high concentration of Li ions (>75%). The adopted cubic structure shows long-term reversibility, enhanced power with capacity approaching the stochiometry of Li 2Ti 2O 4. The anode shows also superior stability over 600 cycles and exhibits high specific energy (∼200 W h kg electrode -1) delivered at a specific power of ∼30 kW kg electrode -1. The TiO 2 anode in a full Li-ion cell with a LiNi 0.5Mn 1.5O 4 cathode operates at 2.8 V and demonstrates the highest (∼310 mA h/g) reversible specific capacity reported to date. Our conceptually new approach fosters the ability of amorphous nanoscale electrodes to maximize their capacity in operando, opening a new avenue for synthesis of safe and durable high-power/high-capacity batteries.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films