A Facile Surface Reconstruction Mechanism toward Better Electrochemical Performance of Li4Ti5O12 in Lithium‐Ion Battery

Through a facile sodium sulfide (Na2S)‐assisted hydrothermal treatment, clean and nondefective surfaces are constructed on micrometer‐sized Li4Ti5O12 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 Li4Ti5O12 surface in a water‐based hydrothermal environment is a hydrolysis–recrystallization process, which can introduce a new phase of anatase‐TiO2. While, with a small amount of Na2S (0.004 mol L？1 at least), the spinel‐Li4Ti5O12 phase is maintained without a second phase. During this process, the alkaline environment created by Na2S and the surface adsorption of the sulfur‐containing group (HS？ or S2？) can suppress the recrystallization of anatase‐TiO2 and renew the particle surfaces. This finding gives a better understanding of the surface–property relationship on Li4Ti5O12 and guidance on preparation and modification of electrode material other than coating or doping