Synthesis of dot-sheet oxalates via metal-organic framework derivatives for high-performance supercapacitors

Metal-organic frameworks (MOFs) are known to suffer from relatively low conductivity and insufficient stability, which hampers their practical applications in supercapacitors. Here, we report an outstanding dot-decorated sheet ternary transition metal oxalates (TMOXs) using bimetallic MOFs as precursors to overcome these problems. The optimized dot-decorated sheet nickel-cobalt-copper oxalates (NiCoCu-OA) exhibits an excellent specific capacitance of 3003 F g −1 at 1 A g −1 , which are beyond the theoretical capacitance value. Moreover, this electrode exhibited a high energy density of 46.5 Wh kg −1 and power density of 900 W kg −1 in a prepared NiCoCu-OA//AC asymmetric supercapacitor. In addition, the device maintained 87 % capacitance after 10,000 cycles. The outstanding performance of the NiCoCu-OA electrode is attributed not only to the increased fine nanosheets and nanoparticles on its surface, which leads to the participation of more surface electroactive substances in the redox reaction and shortens the diffusion path for rapid charge transfer, but also to the significant synergistic effects between the ternary transition metal ions, which eventually leads to the good electrochemical properties and good stability.