文摘
We report an electrochemically driven transformation of amorphous TiOb>2b> 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 TiOb>2b> 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 TiOb>2b> 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 Lib>2b>Tib>2b>Ob>4b>. The anode shows also superior stability over 600 cycles and exhibits high specific energy (200 W h kgb>electrodeb>鈥?) delivered at a specific power of 30 kW kgb>electrodeb>鈥?. The TiOb>2b> anode in a full Li-ion cell with a LiNib>0.5b>Mnb>1.5b>Ob>4b> 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.