Nickel chromium-LDH/CNT composite for supercapacitors: Synergistic conductive network for superior energy storage

Transition metal-based layered double hydroxides have emerged as promising anode materials for energy storage devices due to their anion exchange capacity, adjustable interlayer spacing, structural versatility, high stability, and cost-effectiveness; however, their limited electrical conductivity poses a challenge to achieving optimal performance. In this line, we have devised a facile and cost-effective method for synthesizing carbon nanotube-loaded nickel chromium-LDH composite, and explored the effect of the incorporation of CNT on the electrochemical properties for supercapacitor application. The synthesized NiCr-LDH/CNT composites are characterized by uniformly distributed carbon nanotubes over hexagonal-shaped NiCr-LDH nanoflakes. The electrode fabricated from the composite exhibited impressive pseudocapacitance behavior, achieving a specific capacitance of 1536 Fg⁻¹ at 1 A g⁻¹, surpassing the 1156 F g⁻¹ capacitance of pristine NiCr-LDH. Asymmetric supercapacitor coin cells were assembled using the as-prepared electrode as the cathode, activated carbon as the anode, Whatman filter paper as the porous separator, and 6 M KOH aqueous solution as the electrolyte, all enclosed within a CR2032 coin cell casing. With a specific capacitance of 384 F g⁻¹ at 1 A g⁻¹ and nearly 87 % capacitance retention after 5000 cycles, these ASCs demonstrated remarkable electrochemical performance and excellent long-term durability. Moreover, the ASCs achieved a high energy density of 77 Wh kg⁻¹ at a power density of 728 W kg⁻¹ and retained 13 Wh kg⁻¹ even at an elevated power density of 9740 W kg⁻¹. Multi-walled carbon nanotubes (MWCNTs) and NiCr-LDH work synergistically to form conductive networks that improve the electrochemical characteristics of NiCr-LDH/CNT composites, making them ideal for energy storage devices.