208 research outputs found
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Carbons and electrolytes for advanced supercapacitors
Electrical energy storage (EES) is one of the most critical areas of technological research around the world. Storing and efficiently using electricity generated by intermittent sources and the transition of our transportation fleet to electric drive depend fundamentally on the development of EES systems with high energy and power densities. Supercapacitors are promising devices for highly efficient energy storage and power management, yet they still suffer from moderate energy densities compared to batteries. To establish a detailed understanding of the science and technology of carbon/carbon supercapacitors, this review discusses the basic principles of the electrical double-layer (EDL), especially regarding the correlation between ion size/ion solvation and the pore size of porous carbon electrodes. We summarize the key aspects of various carbon materials synthesized for use in supercapacitors. With the objective of improving the energy density, the last two sections are dedicated to strategies to increase the capacitance by either introducing pseudocapacitive materials or by using novel electrolytes that allow to increasing the cell voltage. In particular, advances in ionic liquids, but also in the field of organic electrolytes, are discussed and electrode mass balancing is expanded because of its importance to create higher performance asymmetric electrochemical capacitors
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Comment on "Synthesis, characterization and growth mechanism of flower-like vanadium carbide hierarchical nanocrystals"
This Letter is in response to a recent paper by Ma et al. (CrystEngComm, 2010, 12, 750-754) which arguably studied vanadium carbide nanostructures whereas all available evidence indicates the study of vanadium oxide. We feel that it is important to communicate to the community several inconsistencies so that the interesting material reported can be seen in the right light, especially with several groups nowadays having reported similar structures from vanadium oxide synthesis
Mixed Cu-Fe Sulfides Derived from Polydopamine-Coated Prussian Blue Analogue as a Lithium-Ion Battery Electrode
Batteries employing transition-metal sulfides enable high-charge storage capacities, but polysulfide shuttling and volume expansion cause structural disintegration and early capacity fading. The design of heterostructures combining metal sulfides and carbon with an optimized morphology can effectively address these issues. Our work introduces dopamine-coated copper Prussian blue (CuPB) analogue as a template to prepare nanostructured mixed copper-iron sulfide electrodes. The material was prepared by coprecipitation of CuPB with in situ dopamine polymerization, followed by thermal sulfidation. Dopamine controls the particle size and favors K-rich CuPB due to its polymerization mechanism. While the presence of the coating prevents particle agglomeration during thermal sulfidation, its thickness demonstrates a key effect on the electrochemical performance of the derived sulfides. After a two-step activation process during cycling, the C-coated KCuFeS2electrodes showed capacities up to 800 mAh/g at 10 mA/g with nearly 100% capacity recovery after rate handling and a capacity of 380 mAh/g at 250 mA/g after 500 cycles
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Comment on "Sponge-templated preparation of high surface area graphene with ultrahigh capacitive deionization performance"
[no abstract available
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Quinone-decorated onion-like carbon/carbon fiber hybrid electrodes for high-rate supercapacitor applications
The energy performance of carbon onions can be significantly enhanced by introducing pseudocapacitive materials, but this is commonly at the cost of power handling. In this study, a novel synergistic electrode preparation method was developed by using carbon-fiber substrates loaded with quinone-decorated carbon onions. The electrodes are free standing, binder free, extremely conductive, and the interfiber space filling overcomes the severely low apparent density commonly found for electrospun fibers. Electrochemical measurements were performed in organic and aqueous electrolytes. For both systems, a high electrochemical stability after 10â000 cycles was measured, as well as a long-term voltage floating test for the organic electrolyte. The capacitance in 1âM H2SO4 was 288â
Fâg^â1 for the highest loading of quinones, which is similar to literature values, but with a very high power handling, showing more than 100â
Fâg^â1 at a scan rate of 2â
Vs^â1
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Dual-Use of Seawater Batteries for Energy Storage and Water Desalination
Seawater batteries are unique energy storage systems for sustainable renewable energy storage by directly utilizing seawater as a source for converting electrical energy and chemical energy. This technology is a sustainable and cost-effective alternative to lithium-ion batteries, benefitting from seawater-abundant sodium as the charge-transfer ions. Research has significantly improved and revised the performance of this type of battery over the last few years. However, fundamental limitations of the technology remain to be overcome in future studies to make this method even more viable. Disadvantages include degradation of the anode materials or limited membrane stability in aqueous saltwater resulting in low electrochemical performance and low Coulombic efficiency. The use of seawater batteries exceeds the application for energy storage. The electrochemical immobilization of ions intrinsic to the operation of seawater batteries is also an effective mechanism for direct seawater desalination. The high charge/discharge efficiency and energy recovery make seawater batteries an attractive water remediation technology. Here, the seawater battery components and the parameters used to evaluate their energy storage and water desalination performances are reviewed. Approaches to overcoming stability issues and low voltage efficiency are also introduced. Finally, an overview of potential applications, particularly in desalination technology, is provided
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Dual-Use of Seawater Batteries for Energy Storage and Water Desalination
Seawater batteries are unique energy storage systems for sustainable renewable energy storage by directly utilizing seawater as a source for converting electrical energy and chemical energy. This technology is a sustainable and cost-effective alternative to lithium-ion batteries, benefitting from seawater-abundant sodium as the charge-transfer ions. Research has significantly improved and revised the performance of this type of battery over the last few years. However, fundamental limitations of the technology remain to be overcome in future studies to make this method even more viable. Disadvantages include degradation of the anode materials or limited membrane stability in aqueous saltwater resulting in low electrochemical performance and low Coulombic efficiency. The use of seawater batteries exceeds the application for energy storage. The electrochemical immobilization of ions intrinsic to the operation of seawater batteries is also an effective mechanism for direct seawater desalination. The high charge/discharge efficiency and energy recovery make seawater batteries an attractive water remediation technology. Here, the seawater battery components and the parameters used to evaluate their energy storage and water desalination performances are reviewed. Approaches to overcoming stability issues and low voltage efficiency are also introduced. Finally, an overview of potential applications, particularly in desalination technology, is provided
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Growth of titania and tin oxide from Ti2SnC via rapid thermal oxidation in air for lithium-ion battery application
Herein, we report the synthesis of TiO2âSnO2âC/carbide hybrid electrode materials for Li-ion batteries (LIBs) via two different methods of controlled oxidation of layered Ti2SnC. The material was partially oxidized in an open-air furnace (OAF) or using a rapid thermal annealing (RTA) approach to obtain the desired TiO2âSnO2âC/carbide hybrid material; the carbide phase encompassed both residual Ti2SnC and TiC as a reaction product. We tested the oxidized materials as an anode in a half cell to investigate their electrochemical performance in LIBs. Analysis of the various oxidation conditions indicated the highest initial lithiation capacity of 838 mAh/g at 100 mA/g for the sample oxidized in the OAF at 700°C for 1 h. Still, the delithiation capacity dropped to 427 mAh/g and faded over cycling. Long-term cycling demonstrated that the RTA sample treated at 800°C for 30 s was the most efficient, as it demonstrated a reversible capacity of around 270 mAh/g after 150 cycles, as well as a specific capacity of about 150 mAh/g under high cycling rate (2000 mA/g). Given the materialsâ promising performance, this processing method could likely be applied to many other members of the MAX family, with a wide range of energy storage applications
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Mechanically Stable, BinderâFree, and FreeâStanding Vanadium Trioxide/Carbon Hybrid Fiber Electrodes for LithiumâIon Batteries
Binder is a crucial component in present-day battery electrodes but commonly contains fluorine and requires coating processing using organic (often
toxic) solvents. Preparing binder-free electrodes is an attractive strategy to
make battery electrode production and its end-of-use waste greener and safer.
Herein, electrospinning is employed to prepare binder-free and self-standing
electrodes. Such electrodes often suffer from low flexibility, and the correlation between performance and flexibility is usually overlooked. Processing
parameters affect the mechanical properties of the electrodes, and for the
first time it is reported that mechanical flexibility directly influences the
electrochemical performance of the electrode. The importance is highlighted
when processing parameters advantageous to powder materials, such as
a higher heat treatment temperature, harm self-standing electrodes due to
deterioration of fiber flexibility. Other strategies, such as conductive carbon
addition, can be employed to improve the cell performance, but their effect
on the mechanical properties of the electrodes must be considered. Rapid
heat treatment achieves self-standing V2O3 with a capacity of 250 mAh gâ1
at
250 mA gâ1
and 390 mAh gâ1
at 10 mA gâ
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