Synergistic modification of commercial TiO2 by combined carbon sources of critic acid and sodium carboxymethyl cellulose

Commercial TiO2 (c-TiO2) captures growing attention as promising negative materials for Li-ion batteries owing to its high theoretical capacity and low cost, but the impurities deteriorate its electrochemical performance. Herein, a synergistic modification was proposed to ameliorate the electrochemical performance of c-TiO2 by adopting double carbon precursors of critic acid and sodium carboxymethyl cellulose (CMC-Na) to adjust the carbon and Na+-doping contents. For the collocation of 15 wt% citric acid and 4 wt% CMC, the carbonized product at 750 oC achieved the optimized performance (166.2 mAh g-1 after 900 cycles at 500 mA g-1). Combining the structure and composition with CV plots and electrochemical impedance spectra, the thin uniform carbon coating and Ti3+ induced by the Na+-doping promote electric conductivity among and inside the TiO2 particles, while the augmented lattice constant of TiO2 resulted from the Na+-doping also boosts the Li+-ion diffusion, thus giving rise to the distinct optimization of performance.