Constructing a hierarchically structured KNi0.67Co0.33PO4·H2O-graphene hydrogel/Ni foam electrode for superior all-solid-state supercapacitor. Issue 38 (1st September 2021)

• Record Type: Journal Article
• Authors: Ma, Xueying; Feng, Hanfang; Yan, Tianxiang; Zhang, Li; Liu, Xuying; Cao, Shaokui
• Is Part Of: Dalton transactions. Volume 50:Issue 38(2021)
• Page Start: 13276
• Page End: 13285
• Publication Date: 2021-09-01
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d1dt01744f
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : A supercapacitor electrode of a KNi0.67 Co0.33 PO4 ·H2 O-graphene composite hydrogel supported on Ni foam is prepared by one-step hydrothermal method, which achieves great improvement in the electrode surface area and mass-loading of active material. Abstract : A monolithic supercapacitor electrode of a KNi0.67 Co0.33 PO4 ·H2 O-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 Fe2 P/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.