The Plate-Like Hexagonal Ni-Fe-Sr Layered Double Hydroxides as Advanced Electrodes for Electrochemical Energy Storage

Abstract

Some kinds of the plate-like hexagonal layered double complex hydroxides (named Ni-Fe-Sr-LDHs) materials were prepared for energy storage electrodes in this work. It showed good properties with energy densities and cycle life through the electrochemical tests. At 1 A g−1 current density, the specific capacitance of the electrode reached 311.02 F g−1 when the electrolyte was 6 M LiOH. In the long cycle test, the capacitance retention of the electrode maintained at 73.16% after 2000 cycles (current density: 1 A g−1). The morphologies of Ni-Fe-Sr-LDHs were characterized via the scanning electron microscope, transmission electron microscopy and x-ray powder diffraction. The prepared layered double hydroxides were further optimized by doping carbon nanotubes (CNTs). The optimal weight ratio of Ni-Fe-Sr-LDHs to CNTs was 3:1. The specific capacitance in the measurement of galvanostatic charge–discharge increased to 438.74 F g−1, and the stability of long-term cycling was raised to 77.45%. These results indicated that Ni-Fe-Sr-LDHs combined with CNTs would be an ideal electrode material for practical energy storage.