Increasing rigidness of carbon coating for improvement of electrochemical performances of Co3O4 in Li-ion batteries

Carbon coating is an effective approach to enhance the electrochemical properties of transition metal oxide. Herein, we demonstrated that increasing rigidness of carbon coating by incorporating the analogue of Al oxide was able to improve the rate capability and cycling stability of Co3O4. Compared with carbon coating, a hybrid coating consisted of carbon and the analogue of Al oxide (COAl) showed increased rigidness and robustness, which can suppress the massive expansion of Co3O4 upon lithiation, and accordingly, a conductive linkage of carbon over the electrode surface could be well preserved by using a thin hybrid coating. In this way, good electrode integration was obtained together with fast electric conduction and short Li+ diffusion distance. AFM force curve, SEM observation and impedance measurement were carried out to demonstrate the feasibility of our strategy. During the tests of Li-ion batteries, C@Co3O4@COAl exhibited significantly improved rate capability (0.2-20 A g−1) and cycling stability (4000 cycles at 5 A g−1) as compared with C@Co3O4@C, thus manifesting the significant role by increasing the rigidness of carbon coating.