TiO2 Nanoparticles for Li-Ion Battery Anodes: Mitigation of Growth and Irreversible Capacity Using LiOH and NaOH

TiO 2 anatase and rutile nanoparticles with various sizes and morphologies have been synthesized by very facile and scalable methods, involving common acids as catalysts for room-temperature precipitations. A post-treatment including addition of LiOH or NaOH to the particles followed by heating at 180 °C in air or autoclave suppressed crystallite growth of both rutile and anatase. Furthermore, the treatment with LiOH or NaOH consistently increased the first-cycle Coulombic efficiency in half-cells from ∼0.77 to ∼0.90 on average and even to ∼1.00 in some cells. Whether LiOH or NaOH was used, or the amount, did not appear to affect the electrochemical properties significantly. The structural properties were investigated by Rietveld refinement of powder X-ray diffractograms and related to the electrochemical performance in half-cells. The crystal structure, sizes, and morphologies of the TiO 2 nanoparticles were found to depend on the synthesis conditions, e.g., hydrolysis ratio and the type and concentration of the acid catalyst. Furthermore, increasing the size of rutile crystallites from ∼6 to 11 nm decreased the maximal capacity and rate ability of the half-cells. The anatase crystallites showed optimal electrochemical performance for crystallite sizes of ∼5–8 nm.