In situ coupled nickel-based layered double hydroxides with MXene to enhance supercapacitor performance

Abstract

The vivacious surface chemistry and impressive electrical conductivity of MXene make it an alternative two-dimensional material for the storage of electrochemical energy. Herein, Ni-based layered double hydroxides (LDHs) were hydrothermal and grown in situ on Ti₃C₂ to form “sandwich-like” Ti₃C₂@LDHs. The synthesis of sandwich-like Ti₃C₂@LDHs enhanced the electrochemical reactivity and energy storage of Ti₃C₂, but also increased the electrical conductivity and cyclic stability of NiV-LDHs and NiCo-LDHs. The electrochemical properties of Ti₃C₂@NiV-LDHs and Ti₃C₂@NiCo-LDHs composite electrodes were greater than those of NiCo-LDHs, NiV-LDHs and Ti₃C₂, respectively. The optimal mass-specific capacitance of Ti₃C₂@NiV-LDHs was up to 1346.14 F g⁻¹ (1 A g⁻¹), and that of Ti₃C₂@NiCo-LDHs was 1120.07 F g⁻¹ (1 A g⁻¹), which is 1.6- and 1.5-times that of NiV-LDHs and NiCo-LDHs, respectively. A Ti₃C₂@NiV-LDHs//activated carbon (AC) asymmetric supercapacitor cell (ASC) manifested an energy density of 46.34 W h kg⁻¹ (at 1530.61 W kg⁻¹), and the specific capacitance could be maintained at 78.57% after 5000 charge–discharge cycles (10 A g⁻¹). Ti₃C₂@NiCo-LDHs//AC ASC exhibited an energy density of 50.29 W h kg⁻¹ (at 1522.65 W kg⁻¹) with 81.82% specific capacitance retention after 5000 charge–discharge cycles (10 A g⁻¹). Our results provide a procedure for improving the conductivity and stability of Ni-based LDHs using 2D MXenes in an aqueous asymmetric supercapacitor.