The role of “ZrF4-modification” on the structure and electrochemical performance of Li4Ti5O12 anode material

In order to determine the reaction mechanism of the fluoride modification process and its influence on the electrochemical properties of Li4Ti5O12 anode material, the “ZrF4-modified” Li4Ti5O12 was prepared via a co-precipitation method. Structural characterization results shows that both Zr4+ and F− ions were not incorporated into the lattice structure of Li4Ti5O12 after the modification process. Instead, F− reacts with Li4Ti5O12 chemically to generate new impurity phase such as anatase TiO2 and LiF, while Zr4+ forms amorphous ZrO2 nano-particles over the Li4Ti5O12 particles. There was no dense coating layer formed on the surface of the Li4Ti5O12 particles. These results indicate the reaction mechanism of the ZrF4-modification process was different from that previously reported (such as “AlF3, MgF2, ZnF2, SrF2 and CaF2-modification”). The rate capability and cycling stability of Li4Ti5O12 can be enhanced due to the “ZrF4-modification” process. Specifically, the 2 wt% “ZrF4-modified” Li4Ti5O12 shows the best electrochemical performance.