A synergistic electrochemical properties of 3D marigold-like Fe-Cu-Ag phosphate/MWCNTs nanocomposite towards hybrid solid-state supercapatteries

초록

Multi-metallic phosphates are promising electrode materials for supercapatteries owing to their abundant redox-active sites and high intrinsic conductivity. However, the direct loading of these materials onto substrates often results in poor performance. To overcome this challenge, we proposed a hybrid design in which a crystalline/amorphous marigold-like iron-copper-silver phosphate (FCAP) heterostructure is hydrothermally anchored onto multi-walled carbon nanotubes (MWCNTs). However, the MWCNTs were initially functionalized and deposited on nickel foam (NF) via a dip-and-dry approach. Interestingly, the incorporation of MWCNTs enabled the effective encapsulation of redox-active multi-metallic sites with diverse oxidation states, leading to a superior performance. Accordingly, the FCAP-5 nanocomposite delivered an outstanding specific capacity of 1140 C/g (1900 F/g) at 5.0 A/g and maintained a 96.2 % capacity after 10,000 cycles. This remarkable improvement was attributed to the synergistic effects of the trimetallic phosphate and the MWCNTs, which have high electronic conductivity, surface area, and structural stability. Notably, crystalline Cu/Ag compounds provided active sites and mechanical support, whereas the amorphous Fe phase facilitated ion mobility. To demonstrate practical applicability, a hybrid solid-state (HSS) supercapattery was fabricated using FCAP-5 (cathode) and reduced graphene oxide (anode) in a PVA-KOH gel electrolyte. The device achieved a high voltage output of + 1.7 V, with a specific capacity of 164 C/g (45.6 mAh/g), an energy density of 38.7 Wh/kg, and a power density of 1700 W/kg at 2.0 A/g. The device also exhibited an exceptional cycling stability (91.5 %) after 10,000 cycles. Likewise, the serially connected HSS supercapatteries illuminated different colored light-emitting diodes, suggesting that the proposed nanocomposite has significant potential for use in advanced energy storage applications. © 2025 Elsevier B.V.

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