Synthesis of Capsule-like Porous Hollow Nanonickel Cobalt Sulfides via Cation Exchange Based on the Kirkendall Effect for High-Performance Supercapacitors
Abstract:To construct a suitable three-dimensional structure for ionic transport on the surface of the active materials for a supercapacitor, porous hollow nickel cobalt sulfides are successfully synthesized via a facile and efficient cation-exchange reaction in a hydrothermal process involving the Kirkendall effect with γ-MnS nanorods as a sacrificial template. The formation mechanism of the hollow nickel cobalt sulfides is carefully illustrated via the tuning reaction time and reaction temperature during the cation-e… Show more
“…This indicates that after 2000 charge–discharge cycles, the C sp value of the NiCo 2 S 4 electrode exceeds the C sp value of the NiS electrode, although at the initial stage, the C sp value of the NiS electrode is approximately 1.5 times larger than that of the NiCo 2 S 4 electrode. The superior electrochemical properties such as the electrical conductivity, specific capacitance and cycle stability of bimetallic sulfides to those of the corresponding single metal sulfides have also been reported previously [26,30,31]. Overall, the simple fabrication and synergetic improvements of the nanostructured NiCo 2 S 4 electrodes demonstrated in this study can be applied to manufacturing efficient metal sulfide electrodes for supercapacitors.…”
Section: Resultssupporting
confidence: 77%
“…In contrast, the NiS-coated p-TiO 2 electrode showed the lowest C areal retention of 53.1%. The improved voltammetric response of the NiCo 2 S 4 electrode is probably due to the higher electrical conductivity of bimetallic sulfides compared to corresponding single metal sulfides [26]. Figure 3.CV curves measured at various scan rates for the ( a ) NiS, ( b ) Co 3 S 4 and ( c ) NiCo 2 S 4 electrodes.…”
Nanostructured nickel cobalt sulfide (NiCo2S4) electrodes are successfully fabricated using a simple alternate-dip-coating method. The process involves dipping a TiO2 nanoparticles-covered substrate in a nickel/cobalt precursor solution and sulfur precursor solution alternately at room temperature. The fabricated bimetallic sulfide electrode exhibits a synergetic improvement compensating for the disadvantages of the two single metal sulfide electrodes, i.e. the poor cycle stability of the nickel sulfide electrode and the low specific capacitance (Csp) of the cobalt sulfide electrode. The two capacitive properties are optimized by adjusting the ratio of nickel and cobalt concentrations in the metal precursor solution, reaching a Csp of 516 F g−1 at a current density of 1 mA cm−2, with its retention being 99.9% even after 2000 galvanostatic charge–discharge cycles.
“…This indicates that after 2000 charge–discharge cycles, the C sp value of the NiCo 2 S 4 electrode exceeds the C sp value of the NiS electrode, although at the initial stage, the C sp value of the NiS electrode is approximately 1.5 times larger than that of the NiCo 2 S 4 electrode. The superior electrochemical properties such as the electrical conductivity, specific capacitance and cycle stability of bimetallic sulfides to those of the corresponding single metal sulfides have also been reported previously [26,30,31]. Overall, the simple fabrication and synergetic improvements of the nanostructured NiCo 2 S 4 electrodes demonstrated in this study can be applied to manufacturing efficient metal sulfide electrodes for supercapacitors.…”
Section: Resultssupporting
confidence: 77%
“…In contrast, the NiS-coated p-TiO 2 electrode showed the lowest C areal retention of 53.1%. The improved voltammetric response of the NiCo 2 S 4 electrode is probably due to the higher electrical conductivity of bimetallic sulfides compared to corresponding single metal sulfides [26]. Figure 3.CV curves measured at various scan rates for the ( a ) NiS, ( b ) Co 3 S 4 and ( c ) NiCo 2 S 4 electrodes.…”
Nanostructured nickel cobalt sulfide (NiCo2S4) electrodes are successfully fabricated using a simple alternate-dip-coating method. The process involves dipping a TiO2 nanoparticles-covered substrate in a nickel/cobalt precursor solution and sulfur precursor solution alternately at room temperature. The fabricated bimetallic sulfide electrode exhibits a synergetic improvement compensating for the disadvantages of the two single metal sulfide electrodes, i.e. the poor cycle stability of the nickel sulfide electrode and the low specific capacitance (Csp) of the cobalt sulfide electrode. The two capacitive properties are optimized by adjusting the ratio of nickel and cobalt concentrations in the metal precursor solution, reaching a Csp of 516 F g−1 at a current density of 1 mA cm−2, with its retention being 99.9% even after 2000 galvanostatic charge–discharge cycles.
“…Hollow porous nanostructures have been widely used in many fields such as catalysis, gas sensing, drug delivery, and energy storage and conversion due to their low volume density, hollow interior. Correspondingly, many synthesis methods have been developed including traditional template method and novel approaches such as Kirkendall effect, galvanic replacement, chemical etching, and selfcurling . However, these methods are limited because of their complicated preparation technology and not suitable for large‐scale production.…”
Section: Performance Optimization Of Mof‐derived Nanostructure Metal mentioning
Summary
Metal‐organic frameworks (MOFs), as new class of porous materials, are constructed by inorganic metal centers and bridging organic links. Recently, MOFs have been proved to be effective templates for preparing metal oxides with large surface areas and controlled shape by directly annealing in air. There are lots of reports about metal‐organic framework‐derived metal oxides as electrode materials for supercapacitors. Metal‐organic framework‐derived metal oxides can offer higher capacitances compared with that prepared by other synthetic methods, likely attribute to high surface areas and optimal pore sizes. However, at present, the specific capacitances of MOF‐derived metal oxides received are far lower than theoretical values, and the cycle numbers could not meet practical demands. Accordingly, much effort has been made to improve the performance by further modifying MOFs. Thus, this paper focused on the advances in performance optimization of MOF‐derived metal oxide as electrode materials for supercapacitors as follows:
Dual metal MOF‐derived binary metal oxides. Metal oxides with 2 metal cations possess better electrical conductivity and richer redox active sites than single metal oxides.
Metal‐organic framework‐derived carbon/metal oxide composites (MO@C) or graphene/MOF‐derived graphene/metal oxide composites. Doping carbon not only facilitate transportation of electrodes but also contribution to extra double‐layer capacitance.
Hybrid MOF‐derived metal oxide composites (MO@MO). Metal oxide composites can produce some synergistic effects that the individuals cannot provide.
Metal‐organic framework‐derived metal oxides with a hollow structure. The Hollow structure could shorten ion diffusion distance and adapt to volume expansion generated during the ion intercalated/extracted process.
“…Binary metal compounds exhibit excellent electrochemical properties in supercapacitor due to the more rapid charge transportation than the single‐metal compounds . Among of these compounds, the Nickle cobalt sulfides with the capsule‐like structure or dendrite/quasi‐spherical morphology offer a high surface area for electrochemical reaction and suitable paths for ionic transport and exhibit high electrochemical performance . Wan et al synthesized NiCo 2 S 4 porous nanotubes by using a sacrificial template method at a specific capacitance of 1093 F g −1 and current density of 0.2 A g −1 .…”
A simple hydrothermal treatment process was used to prepare urchin‐like NiS@NiCo2S4 composites on Ni foam, which were then employed as binder‐free and conductive‐agent‐free electrodes for pseudocapacitors. The as‐synthesized composites have significant capacitive performance because of the novel porous structure. A specific capacitance up to 14.32 F cm−2 was obtained at a current density of 5 mA cm−2, which was far higher than that of pristine NiCo2S4 nanotube arrays (about 8.4 F cm−2). More importantly, Ni@NiS@NiCo2S4 and activated carbon (AC) were assembled as the positive and negative electrode, respectively, in an asymmetric supercapacitor, which possesses prominent performance. In addition to 78.7 % capacitance retention when cycling at 50 mA cm−2 for 5000 cycles, the as‐fabricated Ni@NiS@NiCo2S4//AC device exhibits a high energy density of 38.96 Wh kg−1 and power density of 339.62 W kg−1 at a current density of 10 mA cm−2.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
