Al-based metal organic framework derived self-assembled carbon nanosheets as innovative anodes for Li- and Na-ion batteries

Functional modification and structural design of carbon electrode materials are considered as a cost-effective method to improve their electrochemical performance. In this study, a solvothermal method is applied to realize self-assembly of the metal-organic framework. After simple carbonization and acid treatment, carbon nanosheets with 2D adjustable defective sub-units are successfully prepared for the first time. It is found that carbonization temperature has a significant effect on the carbon skeleton structure. The optimal nanostructures with large specific surface area and appropriate pore size distribution make self-assembled carbon nanosheets having excellent Li/Na-ion storage properties. In addition, the adjustable carbon skeleton structure can effectively avoid irreversible damage when charge-discharge cycles. For Li-ion batteries, a specific capacity of 825 mAh g(-1) is achieved after 100 cycles at 100 mA g(-1), while for Na-ion batteries a specific capacity of 193 mAh g(-1) is observed after 100 cycles at 100 mA g(-1). Moreover, for Na-ion batteries, even at a high rate of 1000 mA g(-1) the material delivers a specific capacity of 109.5 mAh g(-1) after 3500 cycles.