A novel metal-amino acid assembly is successfully prepared using the simplest amino acid structure - glycine - and nickel nitrate hexahydrate. Two-dimensional porous Ni-Glycine coordination complex [Ni(NH2CH2COO)2](H2O) (CQU-Chen-Gly-Ni-2-1) sheets with 3D nanoflake array structures have been prepared by a facile and cost-effective method. As electrode materials for supercapacitors, the Ni-Glycine coordination complexes display a high specific capacitance of 2.34 F·cm-2 at 1.08 mA·cm-2 (2171.71F·g-1 at a current density of 1 A·g-1), outstanding rate performance (80.77% capacity retention from 1.08 to 10.8 mA·cm-2) and superior cycling performance (2.4% loss after 5000 cycles at 10.8 mA·cm-2). In addition, the optimized asymmetric supercapacitor could be cycled reversibly in the high-voltage region of 0-1.8 V. Furthermore, excellent asymmetric supercapacitors of Ni-Glycine//activated carbon were also fabricated, and exhibited high energy densities of 35.05 and 16.75 Wh·kg-1 at power densities of 900 and 9000 W·kg-1, respectively. These fascinating performances can be attributed to the high capacitances and positive synergistic effects of the two electrodes. The impressive results presented here may pave the way for promising applications in high energy density storage systems.
Keywords: 2D porous materials; Asymmetric supercapacitor; Electrochemical energy storage; Hydrothermal synthesis; Ni-Glycine coordination complexes.
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