Fe incorporated ternary layered double hydroxides with remarkably improved electrochemical performance towards asymmetric supercapacitors

A nanocomposite composed of ternary NiCo2Fex layered double hydroxide (LDH) anchored to g-C3N4 was prepared for high-performance supercapacitor. In this novel material, Fe played an important part in enhancing the energy storage performance of the NiCo2Fex-LDH. Density functional theory calculations on this material showed that Fe improved the Fermi level of NiCo2Fex-LDH, moreover, the stability of the N–Ni bonds were formed after combining NiCo2Fex-LDH with g-C3N4. The electrochemical test results for this material showed that the NiCo2Fe1.0-LDH@g-C3N4 electrode yielded an extremely high specific capacitance of 1550 F g−1 at a current density of 1 A g−1, which was far superior to that of the NiCo2-LDH@g-C3N4 electrode. An assembled NiCo2Fe1.0-LDH@g-C3N4//AC asymmetric supercapacitor device delivered an impressive specific capacitance of 129.64 F g−1, in addition, the device yielded the energy density of up to 35 Wh kg−1 at the corresponding power density of 701 W kg−1 with superior cycling performance (92.7% capacitance retention after 5000 cycles). The NiCo2Fe1.0-LDH@g-C3N4//AC asymmetric supercapacitors easily powered a blue LED. The results of this work provide a promising research path for constructing high-performance of NiCo2-LDH-based nanostructured electrodes materials, which can be employed in new energy storage devices.