2D-1D Nanohybrids of CoCr-Layered Double Hydroxides Coupled with Carbon Nanotubes for High Performance Hybrid Supercapacitor

Though there has been significant progress on the development of supercapacitors (SCs), the challenge of their low energy density remains the same. Moreover, the fabrication of SCs demands easy and cost-effective chemical synthesis processes. Herein, we have synthesized a self-assembled CoCr-LDH-CNT (CCNT) nanohybrid via an exfoliation-restacking method for HSC application. CNTs provide highly conductive hybridization matrix to LDH nanosheets that leads to mesoporous morphology with improved specific surface area and enhanced electrochemical performance of CoCr-LDH. The best-optimized CCNT nanohybrid based electrode shows excellent electrochemical performance with a high specific capacity value of 925 C g^-1 at a current density of 5 A g^-1 as compared to pristine CoCr-LDH (630 C g^-1 at 5 A g^-1). Moreover, an all-solid-state hybrid supercapacitor (HSC) was assembled by utilizing the CCNT nanohybrid as a cathode and activated carbon (AC) as an anode. The CCNT-2//AC HSC device exhibited a high specific capacitance (C_sp) of 97.5 F g^-1 at a current density of 2 A g^-1. Moreover, an HSC device exhibited high energy density of 36.7 Wh kg^-1 at power density of 1.6 kW kg^-1 with capacitance retention of 90.8% at up to 7000 cycles. This work demonstrates that the coupling of 1D CNTs with CoCr-LDH effectively enhances the electrochemical performance of the CoCr-LDH electrode material owing to their synergistic effects.