Issue 38, 2021

Constructing a hierarchically structured KNi0.67Co0.33PO4·H2O-graphene hydrogel/Ni foam electrode for superior all-solid-state supercapacitor

Abstract

A monolithic supercapacitor electrode of a KNi0.67Co0.33PO4·H2O-graphene composite hydrogel supported on Ni foam (KNCP-GH/NF) is first prepared by a one-step hydrothermal method, which achieves notable improvements in the electrode surface area and mass-loading of active materials. The KNCP-GH/NF electrode enjoys a hierarchical open-porous structure, where the KNCP-GH composite hydrogel fills in the voids in NF and the porous graphene hydrogel (GH) simultaneously provides a large support surface for growing active KNCP nanoflowers. Accordingly, the KNCP-GH/NF electrode exhibits a strikingly high capacity of 3240 mC cm−2 (876 C g−1) at 2 mA cm−2 and a satisfactory rate performance with 78.3% retention at 100 mA cm−2. Further, an all-solid-state asymmetric supercapacitor, constituted by using KNCP-GH/NF and Fe2P/GH/NF as the cathode and anode, respectively, and PVA-KOH as the solid-state gel electrolyte, delivers a high energy density of 69.2 W h kg−1 (3.9 mW h cm−3) and a power density of 13 229 W kg−1 (720 mW h cm−3) as well as notable cyclability with 81.2% capacity retention after 10 000 charge/discharge cycles. These attractive performances suggest a promising potential for a hierarchically structured KNCP-GH/NF electrode for the high-performance energy storage application.

Graphical abstract: Constructing a hierarchically structured KNi0.67Co0.33PO4·H2O-graphene hydrogel/Ni foam electrode for superior all-solid-state supercapacitor

Supplementary files

Article information

Article type
Paper
Submitted
28 May 2021
Accepted
13 Aug 2021
First published
18 Aug 2021

Dalton Trans., 2021,50, 13276-13285

Constructing a hierarchically structured KNi0.67Co0.33PO4·H2O-graphene hydrogel/Ni foam electrode for superior all-solid-state supercapacitor

X. Ma, H. Feng, T. Yan, L. Zhang, X. Liu and S. Cao, Dalton Trans., 2021, 50, 13276 DOI: 10.1039/D1DT01744F

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