Fabrication of continuous conductive network for Li4Ti5O12 anode by Cu-doping and graphene wrapping to boost lithium storage

Abstract

Cu-doped Li4Ti5O12/graphene composite (Cu-LTO@FG) was successfully prepared using a facile hydrothermal process coupled with a freeze-drying process. The Cu-doping can produce a large number of structure defects including oxygen vacancies and stacking faults in Li4Ti5O12 nanosheets, greatly improving the intrinsic electrical conductivity. Meanwhile, the graphene network ensures high-efficiency electron conduction and Li+ diffusion not only around the Li4Ti5O12 nanosheets but also through the overall electrode. Thus the as-fabricated composite possesses a continuous conductive path to accelerate the motion of electron and Li+ inside and outside the Li4Ti5O12 nanosheets. The Cu-LTO@FG exhibits superb specific capacity of 177.3 mA h g−1 after 100 cycles at 1 C (1 C = 175 mA h g−1), excellent rate capability up to 20 C with a specific capacity of 160.6 mA h g−1, and outstanding cycling stability as anode material for lithium-ion battery. The extraordinary electrochemical performance is related to the improved electronic conductivity and pseudocapacitive effect, which lead to faster surface charge-transfer and excess lithium-ion storage. In addition, benefiting from the synergistic effect of structure defects and graphene network, the Cu-LTO@FG stores more lithium-ion and alleviates agglomeration of the Li4Ti5O12 nanosheets. Thus, the combined strategy with the Cu-doping and graphene network shows its great potential in improving the performance of anode material for high-rate LIBs.