Deep eutectic solvents (DESs) are a large family of solvents that show many similarities with ionic liquids. They are distinguished by the presence of a large amount of molecular components ...(typically hydrogen bond donors). They are more industrially promising than ionic liquids due to their low cost and tolerance to humidity (hydrolysis or hygroscopicity). As an emerging research field, DESs have already received significant research attention from chemistry scientists. The exploration of DESs used for functional materials in energy and environmental applications is still in its early stage. This review briefly introduces the basics of DESs and how they could be promising as solvents for material scientists. We summarized the application of DESs for the synthesis of materials used for energy and environmental applications. In this review, DESs have been described in view of the three main roles they play in the solution process of functional materials. Besides DESs being widely known as inert media or reactive reagents for the synthesis of materials, they can also be directly adopted as functional materials such as electrolytes for energy storage devices or as CO
2
adsorbents. The present review focused on several categories of functional materials including noble metals, porous carbonaceous materials, transition metal compounds, and DESs themselves, which are synthesized or derived from DESs for potential applications in the energy and environmental fields. DESs have been demonstrated to be effective in guiding the formation of functional materials with unique structures and properties. In particular, we introduced our work on exploring a DES-thermal synthesis strategy, in which the DES is used as a solvent as well as a reagent. Recent theoretical and experimental work for understanding the structural basis of DESs has also been summarized. This review article aims to inspire scientists to use DESs as a powerful tool to push the frontiers in the field of materials, energy, and environmental science.
This review aims to inspire more researchers to explore potential energy and environmental applications of DESs and their derivatives.
The high performance of a pseudocapacitor electrode relies largely on a scrupulous design of nanoarchitectures and smart hybridization of bespoke active materials. We present a powerful two-step ...solution-based method for the fabrication of transition metal oxide core/shell nanostructure arrays on various conductive substrates. Demonstrated examples include Co3O4 or ZnO nanowire core and NiO nanoflake shells with a hierarchical and porous morphology. The “oriented attachment” and “self-assembly” crystal growth mechanisms are proposed to explain the formation of the NiO nanoflake shell. Supercapacitor electrodes based on the Co3O4/NiO nanowire arrays on 3D macroporous nickel foam are thoroughly characterized. The electrodes exhibit a high specific capacitance of 853 F/g at 2 A/g after 6000 cycles and an excellent cycling stability, owing to the unique porous core/shell nanowire array architecture, and a rational combination of two electrochemically active materials. Our growth approach offers a new technique for the design and synthesis of transition metal oxide or hydroxide hierarchical nanoarrays that are promising for electrochemical energy storage, catalysis, and gas sensing applications.
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IJS, KILJ, NUK, PNG, UL, UM
We report a procedure to fabricate nanostructured Ni films via programmed electrochemical deposition from a choline-chloride-based ionic liquid at a high temperature of 90 °C. Three electrodeposition ...modes using constant voltage, pulse voltage, and reverse pulse voltage produce a variety of nanostructured Ni films with micro/nanobinary surface architectures, such as nanosheets, aligned nanostrips, and hierarchical flowers. The nanostructured Ni films possess face-centered cubic crystal structure. Amazingly, it is found that the electrodeposited Ni films deliver the superhydrophobic surfaces without any further modifications by low surface-energy materials, which might be attributed to the vigorous micro/nanobinary architectures and the surface chemical composition. The electrochemical measurements reveal that the superhydrophobic Ni film exhibit an obvious passivation phenomenon, which could provide enhanced corrosion resistance for the substrate in the aqueous solutions.
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Hierarchical NiCo2O4@NiCo2O4 core/shell nanoflake arrays on nickel foam for high-performance supercapacitors are fabricated by a two-step solution-based method which involves in hydrothermal process ...and chemical bath deposition. Compared with the bare NiCo2O4 nanoflake arrays, the core/shell electrode displays better pseudocapacitive behaviors in 2 M KOH, which exhibits high areal specific capacitances of 1.55 F cm–2 at 2 mA cm–2 and 1.16 F cm–2 at 40 mA cm–2 before activation as well as excellent cycling stability. The specific capacitance can achieve a maximum of 2.20 F cm–2 at a current density of 5 mA cm–2, which can still retain 2.17 F cm–2 (98.6% retention) after 4000 cycles. The enhanced pseudocapacitive performances are mainly attributed to its unique core/shell structure, which provides fast ion and electron transfer, a large number of active sites, and good strain accommodation.
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Silicon (Si) is promising for high capacity anodes in lithium‐ion batteries due to its high theoretical capacity, low working potential, and natural abundance. However, there are two main drawbacks ...that impede its further practical applications. One is the huge volume expansion generating during lithiation and delithiation progresses, which leads to severe structural pulverization and subsequently rapid capacity fading of the electrode. The other is the relatively low intrinsic electronic conductivity, therefore, seriously impacting the rate performance. In the past decades, numerous efforts have been devoted for improving the cycling stability and rate capability by rational designs of different nanostructures of Si materials and incorporations with some conductive agents. In this review, the authors summarize the exciting recent research works and focus on not only the synthesis techniques, but also the composition strategies of silicon nanostructures. The advantages and disadvantages of the nanostructures as well as the perspective of this research field are also discussed. We aim to give some reference for engineering application on Si anodes in lithium ion batteries.
The authors summarize the strategies that developed lately for improving the electrochemical performance of Si materials. Special focus in this review is the recent progresses in the rational fabrication of Si nanostructures with multiple morphologies, including nanoparticles, nanowires, thin films, and porous structures. Moreover, further improvement tactics, such as collaborating with carbonaceous materials, conductive polymers, and alloy materials are also discussed.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Dendrite-like ZnO@Ag heterostructure nanocrystals are designed and fabricated by a facial two-step chemical method in a large scale. The heterostructure nanocrystals are composed of single crystal Ag ...nanowires as trunks and highly dense (0001) oriented ZnO nanorods as branches. ZnO nanorods with diameters of about 50−400 nm are vertically grown on the six lateral surfaces of the Ag nanowires. Ultrathin ZnO nanowires or nanotubes with a diameter of less than 30 nm are decorated on the ZnO nanorods. The photocatalysis test shows that the ZnO@Ag heterostructures exhibit a higher photocatalytic activity than the pure ZnO nanorods, thereby implying that the Ag/ZnO interfaces promote the separation of photogenerated electron−hole pairs and enhance the photocatalytic activity.
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Electrochromism refers to the persistent and reversible change of optical properties by an applied voltage pulse.Electrochromic（EC）devices have been extensively studied because of their commercial ...applications in smart windows of green buildings,display devices and thermal control of equipments.In this review,a basic EC device design is presented based on useful oxides and solid-state electrolytes.We focus on the state-of-the-art research activities related to the structures of tungsten oxide（WO3）and nickel oxide（NiO）,summarizing the strategies to improve their EC performances and further applications of devices.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
An elastic and safe electrolyte is demanded for flexible batteries. Herein, a stretchable solid electrolyte comprised of crosslinked elastic polymer matrix, poly(vinylidene ...fluoride‐hexafluoropropylene) (PVDF‐HFP), and flameproof triethyl phosphate (TEP) is fabricated, which exhibits ultrahigh elongation of 450%, nonflammability and ionic conductivity above 1 mS cm−1. In addition, in order to improve the interface compatibility between the electrolyte and Li anode and stabilize the solid‐electrolyte interphase (SEI), a protecting layer containing poly(ethylene oxide) (PEO) is designed to effectively prevent the anode from reacting with TEP and optimize the chemical composition in SEI, leading to a tougher and more stable SEI on the anode. The LiFePO4/Li cells employing this double‐layer electrolyte exhibit an 85.0% capacity retention after 300 cycles at 1 C. Moreover, a flexible battery based on this solid electrolyte is fabricated, which can work in stretched, folded, and twisted conditions. This design of a stretchable double‐layer solid electrolyte provides a new concept for safe and flexible solid‐state batteries.
A stretchable polymer electrolyte is fabricated based on resilient copolymer and poly(vinylidene fluoride‐hexafluoropropylene) (PVDF‐HFP) with ultrahigh elasticity, nonflammability, and good ionic conductivity. A protective layer containing poly(ethylene oxide) (PEO) is designed to protect the electrolyte against the anode and stabilize the solid‐electrolyte interphase (SEI) during cycling. A flexible solid‐state battery is prepared using this double‐layer electrolyte, which can light a light emitting diode (LED) bulb under different deformed conditions.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Polyethylene oxide (PEO)-based solid electrolytes, which exhibit ideal extensibility and wide electrochemical window, are considered as one of the most promising candidates for all solid-state sodium ...batteries (ASSSBs). However, the low mechanical strength and low ionic conductivity hinder their application. Herein, electrospun MgAl
2
O
4
nanofibers are complexed with PEO/NaClO
4
to enhance the mechanical and thermal stability. Determined by
23
Na solid-state nuclear magnetic resonance spectroscopy combined with first-principle calculations, the adsorption energy of ClO
4
−
on the MgAl
2
O
4
surface is far higher than that on PEO, which facilitates the dissociation of Na
+
and ClO
4
−
, thereby enabling a fast transport of Na
+
by the introduction of MgAl
2
O
4
in the polymer electrolyte. The ionic conductivity is enhanced to 1.89 × 10
−4
S cm
−1
from 8.46 × 10
−5
S cm
−1
at 55 °C, and the Na
+
transfer number is improved to 0.55 from 0.26 in the composite electrolyte. The Na//(PEO/MgAl
2
O
4
/NaClO
4
)//Na symmetric cell can cycle for over 400 h at a current density of 0.05 mA cm
−2
and a cut-off capacity of 0.05 mAh cm
−2
while the ASSSBs incorporating the polymer composite electrolyte also exhibit notable rate and cycle performances.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Lithium ion batteries （LIBs） represent one of the most promising solutions for environmentally friendly transportation such as electric vehicles. The demand for high energy density, low cost and ...environmentally friendly batteries makes high-capacity cathode materials very attractive for future LIBs. Layered LiNixCoyMn2O2 （x＋y＋z=1）, Li-rich oxides and Li-V-O compounds have attracted much attention due to their high capacities in recent years. In this review, we focus on the state-of-the-art research activities related to LiNixCoyMn2O2, Li-rich oxides and Li-V-O compounds, including their structures, reaction mechanisms during cycling, challenges and strategies that have been studied to improve their electrochemical performances.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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