Metal-organic frameworks for lithium-sulfur batteries Zheng, Yan; Zheng, Shasha; Xue, Huaiguo ...
Journal of materials chemistry. A, Materials for energy and sustainability,
2019, Letnik:
7, Številka:
8
Journal Article
Recenzirano
Lithium-sulfur (Li-S) batteries have gained popularity over recent decades due to their theoretically superior performance, which renders them a promising new energy storage technology. To cater to ...the increasing demand for energy, suitable and effective materials are desired to constitute Li-S batteries, especially as host materials, separators and interlayers. Metal-organic frameworks (MOFs), novel porous materials, have attracted public attention because of their controllable porous structure and ultrahigh porosity. Moreover, MOF composites and MOF derivatives exhibit even better performance and reduce the shortcomings of pure MOFs. These MOF-based materials are confirmed to be perfect candidates for several important parts in Li-S batteries. In this review, we aim to provide a comprehensive introduction to the excellent performance of pristine MOFs, MOF composites and MOF derivatives in Li-S batteries as host materials, separators or interlayers, including their working mechanism as different constituents. An outlook of possible research directions in the near future and difficulties in development is also given.
The applications of metal-organic frameworks and their composites and derivatives in lithium-sulfur batteries are comprehensively summarized and outlooks of them are given in this review.
Abstract
Most metal–organic frameworks (MOFs) hardly maintain their physical and chemical properties after exposure to alkaline aqueous solutions, thus precluding their use as potential electrode ...materials for electrochemical energy storage devices. Here, we present the design and synthesis of a highly alkaline-stable metal oxide@MOF composite, Co3O4 nanocube@Co-MOF (Co3O4@Co-MOF), via a controllable and facile one-pot hydrothermal method under highly alkaline conditions. The obtained composite possesses exceptional alkaline stability, retaining its original structure in 3.0 M KOH for at least 15 days. Benefitting from the exceptional alkaline stability, unique structure, and larger surface area, the Co3O4@Co-MOF composite shows a specific capacitance as high as 1020 F g−1 at 0.5 A g−1 and a high cycling stability with only 3.3% decay after 5000 cycles at 5 A g−1. The as-constructed solid-state flexible device exhibits a maximum energy density of 21.6 mWh cm−3.
Graphitic carbon nitride (g-C
3
N
4
), with a unique structure analogous to graphite, has attracted ever-increasing attention for electrochemical energy storage due to its high surface area, ...metal-free characteristic, low cost and facile synthesis. Nevertheless, pristine g-C
3
N
4
demonstrates poor electrical conductivity along with serious irreversible capacity loss. Therefore, different categories of g-C
3
N
4
-based materials with enhanced performance have been widely explored. This review mainly introduces g-C
3
N
4
-based materials for application in energy storage devices, including batteries and supercapacitors. The relationship between structures and electrochemical properties is elaborately discussed. Furthermore, historical development, future challenges and prospects in this field are also included.
Graphitic carbon nitride (g-C
3
N
4
), with a unique structure analogous to graphite, has attracted ever-increasing attention for electrochemical energy storage due to its high surface area, metal-free characteristic, low cost and facile synthesis.
Metal-organic frameworks have received increasing attention as promising electrode materials in supercapacitors. In this study, we have successfully synthesized a novel accordion-like Ni-MOF ...superstructure (Ni3(OH)2(C8H4O4)2(H2O)4.2H2O), for the first time, and used it as an electrode material for supercapacitors. The supercapacitors with the novel electrode exhibited excellent electrochemical performance. For example, the accordion-like Ni-MOF electrode showed specific capacitances of 988 and 823 F g-1 at current densities of 1.4 and 7.0 A g-1, respectively, while maintaining outstanding cycling stability (capacitance retention of 96.5% after 5000 cycles at a current density of 1.4 A g-1). More importantly, the accordion-like Ni-MOF and activated carbons were assembled into a high-performance flexible solid-state asymmetric supercapacitor with a specific capacitance of 230 mF cm-2 at a current density of 1.0 mA cm-2. The cycle test showed that the device can offer 92.8% capacity of the initial capacitance at 5.0 mA cm-2 after 5000 cycles with little decay. The maximum energy density of the device can achieve 4.18 mW h cm-3 and the maximum power density can also achieve 231.2 mW cm-3.
Ultrathin 2D Co-MOF nanosheets are successfully synthesized through a facile surfactant-assisted one-pot hydrothermal method. The materials exhibit high specific capacitance as well as excellent ...stability as electrode for high-performance supercapacitors.
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•Ultrathin 2D Co-MOF nanosheets combine the advantages of both 2D nanomaterials and MOFs.•The excellent performance of ultrathin 2D Co-MOF nanosheets for supercapacitors is explained.•Controllable and simple method has been explored.•The mechanism and requirement of the electrodes of high-performance supercapacitors are given.
Ultrathin two-dimensional (2D) cobalt-organic framework (Co-MOF) nanosheets (NS) Co2(OH)2BDC, BDC = 1,4-benzenedicarboxylate are prepared by a facile surfactant-assisted one-pot hydrothermal synthesis. The obtained ultrathin 2D Co-MOF NS are extremely thin, which contributes to their excellent electrical properties and optical transparency. These unique nanostructures make them good candidates as electrode materials for high-performance supercapacitors in terms of enhanced capacitance and stability. In a three-electrode system, ultrathin 2D Co-MOF NS have a maximum specific capacitance of 1159 F g−1 at a current density of 0.5 A g−1. More importantly, the as-prepared electrode exhibits very little capacitance decay after 6000 cycles with 96.7% retention of its original specific capacitance. Meanwhile, the ultrathin 2D Co-MOF NS electrode also offers superior performance in aqueous devices, is better than that of many other metal oxide-based electrodes. We believe that this material sheds light on exploring inexpensive and effective electrodes for high-performance supercapacitors.
Ruthenium based materials and their composite nanomaterials comprehensively summarized and evaluations are given in this review.
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•Ruthenium based materials for supercapacitors have ...been aroused the great interest.•This review provides a comprehensive introduction.•Focusing on synthetic methods and their electrochemical performances.
Ruthenium based materials with rapid reversible redox process, a variety of valence options and flexible environmental adaptability have been aroused researcher’s great interest in the development of supercapacitors. This review provides a comprehensive introduction to the application of ruthenium based materials and their composites in supercapacitors, focusing on their synthetic methods, the selection of raw materials, the control of conditions such as temperature, electrolyte, and pH, as well as their electrochemical performances.
Abstract
Most metal-organic frameworks (MOFs) hardly maintain their physical and chemical properties after exposure to acidic, neutral, or alkaline aqueous solutions, resulting in insufficient ...stability, therefore limiting their applications. Thus, the design and synthesis of stable size/morphology-controlled MOF nanocrystals is critical but challenging. In this study, dual-ligand and hard-soft-acid-base strategies were used to fabricate a variety of 3D pillared-layer Ni(thiophene-2,5-dicarboxylate)(4,4′-bipyridine)n MOF nanocrystals (1D nanofibers, 2D nanosheets and 3D aggregates) with controllable morphology by varying the concentration of 4,4′-bipyridine and thus controlling the crystal growth direction. Owing to the shorter ion diffusion length, enhanced electron/ion transfer and strong interactions between thiophene-2,5-dicarboxylate and 4,4′-bipyridine, the 2D nanosheets showed much larger specific capacitance than 1D nanofibers and 3D aggregates. A single device with an output voltage as high as 3.0 V and exceptional cycling performance (95% of retention after 5000 cycles at 3 mA cm–2) was realized by configuring two aqueous asymmetric supercapacitive devices in series. The excellent cycling property and charge–discharge mechanism are consistent with the hard-soft-acid-base theory.
A unique method combines dual-ligand with hard-soft-acid-base strategies to achieve the morphology-controlled formation of the 3D pillared-layer MOF nanocrystals, which can effectively promote the electrochemical cyclic stability.
In situ
growth of Co
3
O
4
nanocubes on the surface of Co-MOF is an effective way to adjust the surface electron structure of electrocatalysts and increase extra active sites for the OER, the HER and ...overall water splitting. A facile one-pot hydrothermal method can be extended to the preparation of other metal oxide/hydroxide@MOF composites.
The metal oxide/hydroxide@MOF composites have been regarded as a very promising electrocatalyst due to their facile one-step hydrothermal synthesis strategy, high electrocatalytic activity, and excellent cycling stability.
Currently, metal molybdates compounds can be prepared by several methods and are considered as prospective electrode materials in many fields because the metal ions possess the ability to exist in ...several oxidation states. These multiple oxidation states contribute to prolonging the discharge time, improving the energy density, and increasing the cycling stability. The high electrochemical performance of metal molybdates as electrochemical energy storage devices are discussed in this review. According to recent publications and research progress on relevant materials, the investigation of metal molybdate compounds are discussed via three main aspects: synthetic methods, material properties and measured electrochemical performance of these compounds as electrode materials. The recent progress in general metal molybdate nanomaterials for LIBs and supercapacitors are carefully presented here.
Metal molybdate frameworks represent one promising kind of power materials for electrochemical energy storage. Synthesis strategies, tailored materials properties and different electrochemical performances are prominent features for lithium‐ion batteries and supercapacitors. Metal molybdates frameworks and their derivative nanomaterials are comprehensively summarized and evaluations are given in this review.
Taking advantage of the self‐assembling function of amino acids, cobalt–alanine complexes are synthesized by straightforward process of chemical precipitation. Through a controllable calcination of ...the cobalt–alanine complexes, N‐doped Co3O4 nanostructures (N‐Co3O4) and N‐doped CoO composites with amorphous carbon (N‐CoO/C) are obtained. These N‐doped cobalt oxide materials with novel porous nanostructures and minimal oxygen vacancies show a high and stable activity for the oxygen evolution reaction. Moreover, the influence of calcination temperature, electrolyte concentration, and electrode substrate to the reaction are compared and analyzed. The results of experiments and density functional theory calculations demonstrate that N‐doping promotes the catalytic activity through improving electronic conductivity, increasing OH− adsorption strength, and accelerating reaction kinetics. Using a simple synthetic strategy, N‐Co3O4 reserves the structural advantages of micro/nanostructured complexes, showing exciting potential as a catalyst for the oxygen evolution reaction with good stability.
Taking advantage of the self‐assembling property of amino acids, N‐doped Co3O4 nanostructures and N‐doped CoO composited with amorphous carbon are synthesized. Both materials show high, fine‐tunable surface areas and uniform pore structures. The N‐doping, oxygen vacancies, and unique nanostructure features lead to a competitive oxygen evolution reaction performance as well as good stability.
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