Free-Standing, Binder-Free Titania/Super-Aligned Carbon Nanotube Anodes for Flexible and Fast-Charging Li-Ion Batteries

Flexible and durable electrode materials are-of vital importance to developing advanced energy storage devices for emerging wearable electronics. Most current strategies adopt chemical modifications or chemical binders to improve the interface interaction between flexible components, which inevitably lowers the cyclic lifetime and increases the production cost. Here, we report an in situ, scalable sol gel method to fabricate free-standing TiO2/superaligned carbon nanotube (SACNT) hybrid films as flexible anodes in Li-ion batteries. The natural and desirable wettability between TiO2 and SACNTs makes any chemical modifications or chemical binders unnecessary in the fabrication process, delivering a clean TiO2 SACNT interface. The as-prepared TiO2/SACNT anodes not only inherit the high flexibility of the SACNT framework but also enhance rate capability and charge/discharge reversibility with its pseudocapacitive storage mechanism. These anodes exhibit a high capability and a long cyclic lifetime (over 1000 cycles at 60 C) in half cells. They are further assembled to make flexible full cells, where binders, conductive agents, and current collectors are all unnecessary. The capacity decay of a full-cell test is almost negligible over SOO cycles of bending with a fast charging rate within 50 s, suggesting TiO2/SACNT films to be a promising material for flexible storage devices.