https://espace.library.uq.edu.au/view/UQ:113b151/UQ113b151_OA.pdf

Boosting the cycling stability of transition metal compounds-based supercapacitors

In this contribution, we report a facile preparation method of nickel cobalt oxide–reduced graphite oxide (NiCo2O4–rGO) composite material. A fast Faradic process has been realized by sodium dodecyl sulfate (SDS)-induced ultrasmall NiCo2O4 nanocrystals on rGO. As a result, this composite material gives a high specific capacitance of 1222 F g−1 at 0.5 A g−1 and 768 F g−1 at 40 A g−1, showing an outstanding rate capability. An asymmetric supercapacitor device with high energy and power densities has been successfully assembled based on NiCo2O4–rGO composite material and activated carbon. The optimized device shows a high energy density of 23.32 Wh kg−1 at a power density of 324.9 W kg−1. In addition, this asymmetric device shows good stability towards multistage current charge–discharge cycles.

Dodecyl Sulfate Induced Fast Faradic Process in Nickel Cobalt Oxide/Reduced Graphite Oxide Composite Material and Its Application for Asymmetric Supercapacitor Device

The urgent demand for clean energies and rapid development of modern electronic technologies have led to enthusiastic research on novel energy storage technologies, especially for supercapacitors. The most important part is designing electrode materials with excellent capacitive performance. Layered double hydroxides (LDHs) have sparked intense interest among researchers in the past decade due to the facile tunability of their composition, structure and morphology. Various and fruitful accomplishments have been achieved toward developing LDH-based materials for supercapacitor electrodes. This review outlines the recent advances in the designing of LDH-based electrode materials for supercapacitors. Feasible and practical strategies for improving the capacitive performance of LDH-based materials have been discussed and highlighted in terms of tuning the composition of LDHs, designing the electrode structure and assembling applicable supercapacitor devices. Through the ceaseless efforts of scientists, the capacitive performance and practicability of LDH-based materials have been greatly ameliorated, making them more competitive for modern energy storage applications.

Layered double hydroxides toward high-performance supercapacitors

Carbon-containing NiCo2S4 hollow-nanoflake structures were fabricated by a one-step solvothermal method using CS2 as a single source for sulfidation and carbonization. The reaction mechanism for the hollow structure with carbon residues was explored based on the formation of a bis(dithiocarbamate)–metal complex and the Kirkendall effect during solvothermal synthesis. The NiCo2S4 nanoflake electrode exhibited a high specific capacitance of 1722 F g−1 (specific capacity 688.8 C g−1) at a current density of 1 A g−1 and an excellent cycling stability (capacity retention of 98.8% after 10 000 cycles). The as-fabricated asymmetric supercapacitor based on NiCo2S4 nanoflakes and activated carbon electrodes revealed a high energy density of 38.3 W h kg−1 and a high power density of 8.0 kW kg−1 with a capacitance retention of 91.5% and a coulombic efficiency of 95.6% after 5000 cycles, highlighting its great potential for practical supercapacitor applications.

One-step synthesis of hollow C-NiCo2S4 nanostructures for high-performance supercapacitor electrodes.

Sulfur-doped cobalt phosphide nanotube arrays for highly stable hybrid supercapacitor

The emergence of atomically thick nanolayer materials, which feature a short ion diffusion channel and provide more exposed atoms in the electrochemical reactions, offers a promising occasion to optimize the performance of supercapacitors on the atomic level. In this work, a novel monolayer Ni–Co hydroxyl carbonate with an average thickness of 1.07 nm is synthesized via an ordinary one-pot hydrothermal route for the first time. This unique monolayer structure can efficiently rise up the exposed electroactive sites and facilitate the surface dependent electrochemical reaction processes, and thus results in outstanding specific capacitance of 2266 F g–1. Based on this material, an all-solid-state asymmetric supercapacitor is developed adopting alkaline PVA (poly(vinyl alcohol)) gel (PVA/KOH) as electrolyte, which performs remarkable cycling stability (no capacitance fade after 19 000 cycles) together with promising energy density of 50 Wh kg–1 (202 μWh cm–2) and high power density of 8.69 kW kg–1 (35.1 mW c...

Monolayer Nickel Cobalt Hydroxyl Carbonate for High Performance All-Solid-State Asymmetric Supercapacitors

Interface-rich core-shell ammonium nickel cobalt phosphate for high-performance aqueous hybrid energy storage device without a depressed power density

Aqueous hybrid capacitors (HCs) suffer from sacrificed power density and long cycle life due to the insufficient electric conductivity and poor chemical stability of the battery-type electrode material. Herein, we report a novel NH4-Co-Ni phosphate with a stable hierarchical structure combining ultrathin nanopieces and single crystal microplatelets in one system, which allows for a synergistic integration of two microstructures with different length scales and different energy storage mechanisms. The microplatelets with a stable single crystal structure store charge through the intercalation of hydroxyl ions, while the ultrathin nanopieces store charge through surface redox reaction providing enhanced specific capacitance. Furthermore, the large single crystal can bridge the small nanopieces forming continuous electronic conduction paths as well as ionic conduction channels, and facilitate both electron and ion transportation in the hierarchical structure. The HC cell based on the as prepared material and a 3D hierarchical porous carbon delivers a high energy density of 29.6 Wh kg(-1) at a high power density of 11 kW kg(-1). Particularly, an ultralong cycle life along with 93.5% capacitance retention after 10,000 charge-discharge cycles is achieved, which is outstanding among the state-of-the-art aqueous HC cells.

Construction of a novel hierarchical structured NH4-Co-Ni phosphate toward an ultrastable aqueous hybrid capacitor

Morphology Controlled Synthesis of Nickel Cobalt Oxide for Supercapacitor Application with Enhanced Cycling Stability

A multihierarchical structure with (NH4)(Ni, Co)PO4·067H2O microplatelets and (Ni, Co)3(PO4)2·8H2O ultrathin nanopieces anchored on reduced graphene oxide (NCNP/RGO) is synthesized via a mild hydrothermal approach This unique interface-rich structure is suitable for a high power energy storage device by providing efficient pathways for both electronic conduction and ionic transportation, which are effective ways to improve the electrochemical performance Specifically, a specific capacity of 993 F g–1 is obtained in the three-electrode measurement, with ultrahigh capacity retention of 812% (807 F g–1) from 05 to 32 A g–1 The hybrid device constructed with the as-prepared NCNP/RGO as anode and a hierarchical porous carbon (HPC) as cathode offers a very superior energy density of 421 Wh kg–1 at a power density of 73 W kg–1, which remains 32 Wh kg–1 at 14 kW kg–1 Meanwhile, the as-prepared hybrid capacitor exhibits a remarkable cycling stability (965% capacitance retention after 10 000 cycles) The c

Xuejiao Zhang

Papers

Monolayer Nickel Cobalt Hydroxyl Carbonate for High Performance All-Solid-State Asymmetric Supercapacitors

Interface-rich core-shell ammonium nickel cobalt phosphate for high-performance aqueous hybrid energy storage device without a depressed power density

Construction of a novel hierarchical structured NH4-Co-Ni phosphate toward an ultrastable aqueous hybrid capacitor

Morphology Controlled Synthesis of Nickel Cobalt Oxide for Supercapacitor Application with Enhanced Cycling Stability

Multihierarchical Structure of Hybridized Phosphates Anchored on Reduced Graphene Oxide for High Power Hybrid Energy Storage Devices