Advanced Asymmetric Supercapacitors Based on Ni(OH)₂/Graphene and Porous Graphene Electrodes with High Energy Density

TLDR

Ni(OH)₂/graphene and porous graphene possess unique structures that confer excellent electrochemical performance. The study aims to achieve high energy and power densities by fabricating a high‑voltage asymmetric supercapacitor using Ni(OH)₂/graphene and porous graphene electrodes. Hierarchical flower‑shaped Ni(OH)₂ on graphene was synthesized via a microwave‑assisted method, and the resulting material was used as the positive electrode in a high‑voltage asymmetric supercapacitor paired with porous graphene as the negative electrode. The optimized device delivers a reversible 0–1.6 V window with a maximum specific capacitance of 218.4 F g⁻¹ and an energy density of 77.8 Wh kg⁻¹, retains 94.3 % capacitance after 3000 cycles, and its performance is attributed to the high capacitance and synergistic effects of the two electrodes, indicating promise for high‑energy‑density storage.

Abstract

Abstract Hierarchical flowerlike nickel hydroxide decorated on graphene sheets has been prepared by a facile and cost‐effective microwave‐assisted method. In order to achieve high energy and power densities, a high‐voltage asymmetric supercapacitor is successfully fabricated using Ni(OH) 2 /graphene and porous graphene as the positive and negative electrodes, respectively. Because of their unique structure, both of these materials exhibit excellent electrochemical performances. The optimized asymmetric supercapacitor could be cycled reversibly in the high‐voltage region of 0–1.6 V and displays intriguing performances with a maximum specific capacitance of 218.4 F g −1 and high energy density of 77.8 Wh kg −1 . Furthermore, the Ni(OH) 2 /graphene//porous graphene supercapacitor device exhibits an excellent long cycle life along with 94.3% specific capacitance retained after 3000 cycles. These fascinating performances can be attributed to the high capacitance and the positive synergistic effects of the two electrodes. The impressive results presented here may pave the way for promising applications in high energy density storage systems.