2D-2D nanohybrids of Ni–Cr-layered double hydroxide and graphene oxide nanosheets: Electrode for hybrid asymmetric supercapacitors

초록

Nanohybrids of 2D Ni–Cr-layered double hydroxide (Ni–Cr-LDH) and graphene oxide (GO) nanosheets (Ni–Cr-LDH–GO) are prepared by electrostatic self-assembly between cationic Ni–Cr-LDH nanosheets and anionic GO nanosheets. Anionic GO nanosheets provide charge-transporting conducting channels leading to remarkably improved electrochemical activity of Ni–Cr-LDH–GO nanohybrid. The unique Ni–Cr-LDH–GO nanohybrid electrodes enable stable electrochemical structure, abundant active electrochemical sites, and fast electron-transporting channels, which play a crucial role in improving the specific capacities, cycle stability, and rate capacity. As a result, Ni–Cr-LDH–GO nanohybrid electrodes demonstrate excellent electrochemical performance with a specific capacity of 815 C g–1 at 1 A g–1, superior to pristine Ni–Cr-LDH (354 C g–1). An aqueous hybrid supercapacitor (AHS) device displays outstanding electrochemical performance with improved energy density (ED) of 51.85 Wh kg–1 and power density (PD) of 1.34 kW kg–1. An all-solid-state hybrid supercapacitor (ASSHS) displays ED of 38.51 Wh kg–1 and PD of 1.33 kW kg–1. Furthermore, AHS and ASSHS show excellent cycling stability of 89% and 86% capacitance retention after 10,000 galvanostatic charge/discharge (GCD) cycles, respectively. The present exfoliation-restacking strategy provides a useful method for developing a 2D-2D Ni–Cr-LDH–GO structure for a highly active hybrid-type supercapacitor structure. © 2022

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