Capacitors began their journey in 1745, and to date have advanced in the form of supercapacitors. Supercapacitors are one of the advanced forms of capacitors with higher energy density, bridging capacitors and batteries. The energy storage through the formation of an electrical double layer is pivotal for supercapacitor technology. Accordingly, to further improve the energy density, surface faradaic (pseudocapacitive) processes are employed, and henceforth, the journey of chemical supercapacitors commenced. Herein, the materials, mechanisms and fabrication of chemical supercapacitors based on metallic compounds and conducting polymers are discussed in detail. The inherent limitations of these materials are addressed, and the feasible mitigation measures are identified. Poor conductivity, slow diffusion kinetics and rapid structural disintegration over cycling are the common constraints of metallic compounds, which can be overcome by preparing conductive nanocomposites. Thus, versatile conductive nanocomposites of metal oxides, hydroxides, carbides, nitrides, phosphides, phosphates, phosphites, and chalcogenides are elaborated. A lack of structural integrity is the prime obstacle for the realization of conducting polymer-based supercapacitors, which may be solved by forming composites with robust support from carbonaceous materials or metallic compounds. Consequently, the composites of polyaniline, polypyrrole, polythiophene and polythiophene-derivatives are discussed. The historical accounts of early stages of works are emphasised in order to review the developmental pathways of chemical supercapacitors. The construction of full cells and their performance data are presented herein, which synchronize the behaviour of practical scaled-up devices. To the best of our knowledge, this review is the first holistic description of chemical supercapacitors based on metallic compounds and conducting polymers from the first reports to recent advancements.

Chemical supercapacitors: a review focusing on metallic compounds and conducting polymers

The synthesis of layered double hydroxide (LDH) as electroactive material has been well reported; however, fabricating an LDH electrode with excellent electrochemical performance at high current density remains a challenge. In this paper, we report a 3D hierarchical porous flower-like NiAl-LDH grown on nickel foam (NF) through a liquid-phase deposition method as a high-performance binder-free electrode for energy storage. With large ion-accessible surface area as well as efficient electron and ion transport pathways, the prepared LDH-NF electrode achieves high specific capacity (1250 C g−1 at 2 A g−1 and 401 C g−1 at 50 A g−1) after 5000 cycles of activation at 20 A g−1 and high cycling stability (76.7% retention after another 5000 cycles at 50 A g−1), which is higher than those of most previously reported NiAl-LDH-based materials. Moreover, a hybrid supercapacitor with LDH-NF as the positive electrode and porous graphene nanosheet coated on NF (GNS-NF) as the negative electrode, delivers high energy density (30.2 Wh kg−1 at a power density of 800 W kg−1) and long cycle life, which outperforms the other devices reported in the literature. This study shows that the prepared LDH-NF electrode offers great potential in energy storage device applications.

High-Performance Hybrid Supercapacitor with 3D Hierarchical Porous Flower-like Layered Double Hydroxide Grown on Nickel Foam As Binder-Free Electrode

Supercapacitors (SCs) are energy storage devices with unique characteristics, and together with batteries have generated a significant research effort, with various types of electrode materials been developed over the last...

Advances in Pseudocapacitive and Battery-like Electrode Materials for High Performance Supercapacitors

A review on the current research on microwave processing techniques applied to graphene-based supercapacitor electrodes: An emerging approach beyond conventional heating

Facile construction of MgCo2O4@CoFe layered double hydroxide core-shell nanocomposites on nickel foam for high-performance asymmetric supercapacitors

High-performance supercapacitor based on graphene oxide through in-situ polymerization and co-precipitation method

Structure and properties of composite Ni–Co–Mn coatings on metal interconnects by electrodeposition

Ternary ZnO/Co3O4/NiO inherited layered core-shell structure from a double template for high performanced supercapacitor

In this study, a flower–like BiVO4/MIL–101–NH2 composite is synthesized by a facile and surfactant–free process. The –COO−–Bi3+ ionic bond construction was conductive to enhance the interface affinity between BiVO4 and MIL–101–NH2. Due to the highly efficient light capture and sufficient electron traps induced by oxygen vacancies and the formation of a heterostructure, the improved separation and transportation rates of charge carriers are realized. In addition, the MIL–101–NH2/BiVO4 composite is favorable for Cr(VI) photocatalytic removal (91.2%). Moreover, FNBV–3 (Fe/Bi = 0.25) also exhibited an excellent reusability after five cycles.

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BiVO4–Deposited MIL–101–NH2 for Efficient Photocatalytic Elimination of Cr(VI)

The invention belongs to the technical field of composite material preparation, and relates to a preparation method of a graphene oxide composite zinc-cobalt-nickel multi-metal hydroxide ternary composite material. The preparation method comprises the steps of firstly, synthesizing a composite template GO/ZIF-8 by utilizing an aging process; adding the GO/ZIF-8 into ethyl alcohol containing cobaltnitrate hexahydrate and nickel nitrate hexahydrate, uniformly stirring, etching away the ZIF-8 template, and generating the GO/Zn-Co-Ni LDHs ternary composite material of a cotton yarn-shaped fluffystructure under the action of a precipitator. The preparation method is simple and low in cost. Due to the synergistic effect of the multi-metal oxidation-reduction reaction and the GO double-electric-layer effect and the fluffy porous staggered structure of the material, more tracks are provided for transmission of electrons and ions, a higher diffusion rate is given, and finally formation of excellent electrochemical performance can be promoted. Electrochemical tests show that the prepared material has excellent electrochemical properties, such as capacitance property, rate capability and cycling stability, and can be used as an electrode material of a supercapacitor.

Tiantian Zhou

Papers

High-performance supercapacitor based on graphene oxide through in-situ polymerization and co-precipitation method

Structure and properties of composite Ni–Co–Mn coatings on metal interconnects by electrodeposition

Ternary ZnO/Co3O4/NiO inherited layered core-shell structure from a double template for high performanced supercapacitor

BiVO4–Deposited MIL–101–NH2 for Efficient Photocatalytic Elimination of Cr(VI)

Preparation method and application of graphene oxide composite zinc-cobalt-nickel multi-metal hydroxide ternary composite material