Integrated novel carbon materials/layered double metal hydroxides component and function towards enhanced electrochemical performance of supercapacitor

Abstract

Layered double hydroxides (LDH) are promising as electrode materials for supercapacitors. However, their poor stability and electrical conductivities limit the further improvement of their electrochemical properties. Herein, Co−Ni LDH are well built on a conductive substrate of MXene-Ti3C2Tx and multiwalled carbon nanotubes (MWCNTs) using a one-step hydrothermal method to form vertically oriented two-domensional nanoarrays. The combination of MXene-Ti3C2Tx and MWCNTs not only serves as a substrate for the growth of Co−Ni LDH nanoarrays but also effectively maintains the overall layered structure, endowing the whole MXene-Ti3C2Tx/MWCNTs/Co−Ni LDH (MX-CNT-LDH) composite with abundant conductive channels and a stable multilayer structure to achieve excellent electrical conductivity and good cycle stability. The MX-CNT-LDH electrode possesses a surprisingly high specific capacity of 1382.2 ± 2 C g − 1 at a current of 1 A g − 1 and a good rate capability of 70.1% capacitance retention at 20 A g − 1. In addition, asymmetric supercapacitors constructed using MX-CNT-LDH exhibit a high-energy density of 78.7 ± 0.8 W kg−1 at a power density of 800 kW kg−1 and superior capacitance retention (96.7%) and Coulombic efficiency (97.2%) at 6 A g − 1 for 6000 cycles.