Structure, Stoichiometry, and Electrochemical Performance of Li2CoTi3O8 as an Anode Material for Lithium‐Ion Batteries

Abstract Li 2 CoTi 3 O 8 powder has been synthesized by a simple citric nitrate method and was evaluated as an anode material for lithium‐ion batteries. The X‐ray diffraction (XRD) Rietveld refinement and X‐ray photoelectron spectroscopy (XPS) measurements indicate the existence of Ti‐site deficiency and a mixed‐valence state of Co ions in the Li 2 CoTi 3 O 8 structure. The refined site‐occupation result gave a nonstoichiometric chemical formula of Li 2 CoTi 2.682 O 8 , which corresponds to a theoretical specific capacity of 322 mA h g −1 , which is much higher than that of the stoichiometric material (233 mA h g −1 ). The synthesized Li 2 CoTi 2.682 O 8 material exhibits high reversible capacity (ca. 320 mA h g −1 ), and excellent cycling stability and rate capability. A specific capacity of about 240 and 160 mA h g −1 can be achieved at 2 and 6 A g −1 , respectively, by the Li 2 CoTi 2.682 O 8 material. First‐principles calculation demonstrates that Ti‐site deficiency decreases the bandgap and thus facilitates the electron conduction.