Growth of NiMn LDH nanosheet arrays on KCu7S4 microwires for hybrid supercapacitors with enhanced electrochemical performance†
The rational design and synthesis of hierarchical three-dimensional nanostructures with diversified compositions and fascinating morphologies can provide abundant choices and enhanced probability for applications in the energy storage field. Herein, we report an effective, metal catalyst- or surfactant-free approach for the controlled growth of hierarchical one-dimensional (1D)/two-dimensional (2D) nanostructures. The quasi-paralleled and interlaced nanosheet arrays of NiMn layered double hydroxides are grown on KCu7S4 microwires with a quasi-one-dimensional channel. The supersaturation of the system and screw dislocation-driven growth pattern of 2D materials could be key factors in determining the structure of the nanosheets arrays of NiMn LDHs. The electrochemical investigation shows that the KCu7S4@NiMn LDHs have a significantly enhanced specific capacitance (879 F g−1 at 1 mV s−1, 733.8 F g−1 at 1 A g−1) and rate capability (76.9% retention at 30 A g−1) that far exceed those of the reported individual KCu7S4 electrodes. A hybrid supercapacitor based on KCu7S4@NiMn LDH//activated graphene electrode also presents good cycle stability (an 84.8% capacitance retention after 16 000 cycles). The outstanding supercapacitor performance forebode the enormous potential of KCu7S4@NiMn LDH composites in electrochemical properties.