Substantially Improved Na-Ion Storage Capability by Nanostructured Organic-Inorganic Polyaniline-TiO₂ Composite...

Developing sodium (Na)-ion batteries is highly appealing because they offer the potential to be made from raw materials, which hold the promise to be less expensive, less toxic, and at the same time more abundant compared to state-of-the-art lithium (Li)-ion batteries. In this work, the Na-ion storage capability of nanostructured organic-inorganic polyaniline (PANI) titanium dioxide (TiO₂) composite electrodes is studied. Self-organized, carbon-coated, and oxygen-deficient anatase TiO_2- -C nanotubes (NTs) are fabricated by a facile one-step anodic oxidation process followed by annealing at high temperatures in an argon-acetylene mixture. Subsequent electropolymerization of a thin film of PANI results in the fabrication of highly conductive and well-ordered, nanostructured organic-inorganic polyaniline-TiO₂ composite electrodes. As a result, the PANI-coated TiO_2- -C NT composite electrodes exhibit higher Na storage capacities, significantly better capacity retention, advanced rate capability, and better Coulombic efficiencies compared to PANI-coated Ti metal and uncoated TiO_2- -C NTs for all current rates (C-rates) investigated.