Role of pore hierarchy and Mn incorporation on the electrochemical performance of bimetallic NiMn-LDHs on graphite foil for supercapattery application

Abstract

In this work, nickel-manganese layered double hydroxides (NiMn-LDHs) are synthesized using hexamethylenetetramine (HMTA) and urea as precipitating agents via hydrothermal synthesis route. The materials have different flower like microstructure and porosity. The effect of microstructures, porosity and mass loading of the LDHs on the overall electrochemical performance is thoroughly studied in this work. It is observed that HMTA assisted NiMn-LDH having open flower like microstructure delivers a high specific capacity of 719 C g−1 at 1 A g–1 and excellent capacity retention of 82.6% and 86% for 10,000 CV and 5000 GCD cycles, respectively. Furthermore, a supercapattery device assembled using NiMn-LDH@HMTA as cathode and activated carbon as anode exhibit high-capacity retention of 80.1% after 5000 GCD cycles along with an energy density of 50 and 34 Wh kg–1 at power densities of 800 and 4000 W kg–1, respectively.