Hydrothermal synthesis of Co3O4 microspheres as anode material for lithium-ion batteries

Co3O4 microspheres were synthesized in mass production by a simple hydrothermal treatment. One micrometer-sized spherical particles with well-crystallization could be obtained by XRD and SEM. Higher specific surface area (93.4 m2 g−1) and larger pore volume (78.4 cm3 g−1) by BET measurements offered more interfacial bondings for extra sites of Li+ insertion, which resulted in the anomalous large initial irreversible capacity and capacity cycling loss due to SEI film formation. The capacity retention of Co3O4 microspheres involved first forming acted as Li-ion anode material is almost above 90% from 12th cycle and it retain lithium storage capacity of 550.2 mAh g−1 after 25 cycles, which show good long-life stability. The electrochemical impedance spectroscopy (EIS) tests before and after cyclic voltammetry measurements and charge–discharge experiments were carried out and the corresponding DLi values were also calculated. The relationship of the ac impedance spectra and the cycling behaviors was discussed. It is found that the decrease of capacity results from the larger Li+ charge-transfer impedance and the lower lithium-diffusion processes on cycling, which is in very good agreement with the electrochemical behaviors of Co3O4 electrode.