Enhanced Electrochemical Performance of NiFe-LDH@CNT Nanocomposite for High-Energy Supercapacitors

The excellent electrochemical stability, high specific capacitance, cost-effectiveness, and compatibility with other conductive materials make nickel iron-layered double hydroxide (NiFe-LDH) a promising electrode material. However, low electrical conductivity, restricted ion mobility, difficult synthesis, and scaling issues limit its application in supercapacitors. The electrochemical characteristics of NiFe-LDH are significantly improved when combined with carbonaceous materials, such as carbon nanotubes (CNT), leading to increased stability, improved rate performance, and enhanced charge storage capacity. With this motivation, a cost-effective, facile, and scalable synthesis protocol has been devised to prepare bare NiFe-LDH and MWCNT-loaded NiFe-LDH composites employing the hydrothermal method at 180 °C. Thereafter, electrodes were fabricated using as-synthesized materials employing a screen-printing process. The electrochemical findings revealed that the inclusion of CNTs into NiFe-LDH has significantly improved the stability and charge storage capacity, as the NiFe-LDH@CNT electrode demonstrated an enhanced specific capacitance (Cs) of 1243 F g–1 (522 C g–1 or 138 mAh g–1) and capacitance retention (CR) of 87% after 6000 number of cycles (N), compared to the bare NiFe-LDH electrode (Cs = 834 F g–1 CR ∼ 73% and N = 6000). The remarkable improvement in the electrochemical characteristics is endorsed by the effective integration of NiFe-LDH and CNTs, forming a distinctive composite with superior properties for supercapacitor applications. An asymmetric supercapacitor with a power density of 1136 W kg–1 and energy density of 57.6 Wh kg–1 was fabricated using NiFe-LDH@CNT as the cathode and activated carbon (AC) as the anode. The performance of the fabricated asymmetric supercapacitors (ASCs) was evaluated by powering digital thermometers for prolonged periods, demonstrating their versatility for specific applications.