A Facile Surface Reconstruction Mechanism toward Better Electrochemical Performance of LiTiO in Lithium-Ion Battery.

Through a facile sodium sulfide (NaS)-assisted hydrothermal treatment, clean and nondefective surfaces are constructed on micrometer-sized LiTiO particles. The remarkable improvement of surface quality shows a higher first cycle Coulombic efficiency (≈95%), a significantly enhanced cycling performance, and a better rate capability in electrochemical measurements. A combined study of Raman spectroscopy and inductive coupled plasma emission spectroscopy reveals that the evolution of LiTiO surface in a water-based hydrothermal environment is a hydrolysis-recrystallization process, which can introduce a new phase of anatase-TiO. While, with a small amount of NaS (0.004 mol L at least), the spinel-LiTiO phase is maintained without a second phase. During this process, the alkaline environment created by NaS and the surface adsorption of the sulfur-containing group (HS or S) can suppress the recrystallization of anatase-TiO and renew the particle surfaces. This finding gives a better understanding of the surface-property relationship on LiTiO and guidance on preparation and modification of electrode material other than coating or doping.