Author
Winny Dong
Other affiliations: University of California, Los Angeles, California Polytechnic State University
Bio: Winny Dong is an academic researcher from California State Polytechnic University, Pomona. The author has contributed to research in topics: Aerogel & Vanadium oxide. The author has an hindex of 8, co-authored 16 publications receiving 413 citations. Previous affiliations of Winny Dong include University of California, Los Angeles & California Polytechnic State University.
Topics: Aerogel, Vanadium oxide, Sol-gel, Thermoelectric effect, Alkoxide
Papers
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TL;DR: In this article, the effects of surface area and pore volume on the electrochemical behavior of high surface area V2O5 gels dried by either supercritical or ambient methods are explored.
Abstract: : This article explores the effects of surface area and pore volume on the electrochemical behavior of high surface area V2O5 gels dried by either supercritical or ambient methods. Traditional composite electrode structures have prevented truly quantitative analysis of surface area effects in nanoscale battery materials, as well as a study of their innate electrochemical behavior. These limitations can be overcome by using the sticky-carbon' electrode technique, which provides a direct electroanalysis of the active material without the use of a composite electrode structure. The resulting electrochemical measurements show pseudocapacitive behavior (1000 - 2000 F/g) that has not previously been seen for V2O5 aerogels. The relationship between capacitance and pore accessibility is investigated.
165 citations
TL;DR: In this article, an ambient pressure method for drying sol-gel materials has been used to synthesize highly porous vanadium oxide and molybdenum oxide materials with aerogel-like properties.
70 citations
TL;DR: In this paper, a mixture of sol-gel methods was used to synthesize molybdenum oxide aerogels and xerogels with densities between 1.5-2.0 g/cm3 and surface areas less than 10 m2/g.
Abstract: Monolithic molybdenum oxide aerogels and xerogels were synthesized by sol–gel methods using a variety of sol compositions from the system Mo(OC3H7)5/MoCl3(OC3H7)2/acetonitrile/nitric acid/H2O. The aerogels were found to be of density 0.1–0.2 g/cm3 with surface areas between 150–180 m2/g. The xerogels had densities between 1.5–2.0 g/cm3 and surface areas less than 10 m2/g. The as-prepared gels are amorphous materials with compositions corresponding to MoO3−x·1.0H2O·0.3CH3NH2. Crystallization to the orthorhombic phase occurs at 350°C. Electrochemical measurements demonstrate that lithium can be intercalated reversibly into the aerogel structure. An ambient pressure drying method based on the use of low surface tension solvents produced monolithic gels with high surface areas (250–270 m2/g) and densities between 0.7–0.9 g/cm3.
50 citations
TL;DR: In this article, a three-dimensional molybdenum oxide network is achieved by suppressing MoO bond formation through a ligand exchange process, and IR spectroscopy is used to characterize the bond formations during gelation, aging, and drying of the gels.
Abstract: Monolithic molybdenum trioxide aerogels and xerogels have been synthesized by the sol–gel method. A three-dimensional molybdenum oxide network is achieved by suppressing MoO bond formation through a ligand exchange process. IR spectroscopy is used to characterize the bond formations during gelation, aging, and drying of the gels. The as-prepared aerogels are low density (0.15–0.30 g cm–3) amorphous materials with surface areas of 150–180 m2 g–1 . Upon heating to 400 °C, the amorphous solids crystallize to orthorhombic MoO3 .
45 citations
TL;DR: In this paper, the authors exploit sol-gel synthesis to synthesize nanocomposite electrodes in which aerogels are in intimate contact with carbon nanotubes, which leads to extraordinary electrochemical properties, including an extremely high capacity for lithium and electrochemical responses that are both batterylike and capacitor-like.
Abstract: The electrochemical properties of high surface area transition metal oxide aerogels are extremely interesting because aerogels serve to amplify surface effects. As a result, the electrochemical properties are dominated by surfaces rather than by bulk behavior. In the case of vanadium oxide aerogels this leads to extraordinary electrochemical properties, including an extremely high capacity for lithium and electrochemical responses that are both battery-like and capacitor-like. By exploiting sol-gel synthesis, it is possible to synthesize nanocomposite electrodes in which aerogels are in intimate contact with carbon nanotubes. The resulting nanocomposites exhibit superior electrochemical properties, especially at high discharge.
43 citations
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TL;DR: A brief historical review of the development of lithium-based rechargeable batteries is presented, ongoing research strategies are highlighted, and the challenges that remain regarding the synthesis, characterization, electrochemical performance and safety of these systems are discussed.
Abstract: Technological improvements in rechargeable solid-state batteries are being driven by an ever-increasing demand for portable electronic devices. Lithium-ion batteries are the systems of choice, offering high energy density, flexible and lightweight design, and longer lifespan than comparable battery technologies. We present a brief historical review of the development of lithium-based rechargeable batteries, highlight ongoing research strategies, and discuss the challenges that remain regarding the synthesis, characterization, electrochemical performance and safety of these systems.
17,496 citations
TL;DR: This review describes some recent developments in the discovery of nanoelectrolytes and nanoeLECTrodes for lithium batteries, fuel cells and supercapacitors and the advantages and disadvantages of the nanoscale in materials design for such devices.
Abstract: New materials hold the key to fundamental advances in energy conversion and storage, both of which are vital in order to meet the challenge of global warming and the finite nature of fossil fuels. Nanomaterials in particular offer unique properties or combinations of properties as electrodes and electrolytes in a range of energy devices. This review describes some recent developments in the discovery of nanoelectrolytes and nanoelectrodes for lithium batteries, fuel cells and supercapacitors. The advantages and disadvantages of the nanoscale in materials design for such devices are highlighted.
8,157 citations
TL;DR: Two important future research directions are indicated and summarized, based on results published in the literature: the development of composite and nanostructured ES materials to overcome the major challenge posed by the low energy density.
Abstract: In this critical review, metal oxides-based materials for electrochemical supercapacitor (ES) electrodes are reviewed in detail together with a brief review of carbon materials and conducting polymers. Their advantages, disadvantages, and performance in ES electrodes are discussed through extensive analysis of the literature, and new trends in material development are also reviewed. Two important future research directions are indicated and summarized, based on results published in the literature: the development of composite and nanostructured ES materials to overcome the major challenge posed by the low energy density of ES (476 references).
7,642 citations
TL;DR: In this article, the pseudocapacitance properties of transition metal oxides have been investigated and a review of the most relevant pseudo-capacitive materials in aqueous and non-aqueous electrolytes is presented.
Abstract: Electrochemical energy storage technology is based on devices capable of exhibiting high energy density (batteries) or high power density (electrochemical capacitors). There is a growing need, for current and near-future applications, where both high energy and high power densities are required in the same material. Pseudocapacitance, a faradaic process involving surface or near surface redox reactions, offers a means of achieving high energy density at high charge–discharge rates. Here, we focus on the pseudocapacitive properties of transition metal oxides. First, we introduce pseudocapacitance and describe its electrochemical features. Then, we review the most relevant pseudocapacitive materials in aqueous and non-aqueous electrolytes. The major challenges for pseudocapacitive materials along with a future outlook are detailed at the end.
3,930 citations
TL;DR: The development of novel materials is a fundamental focal point of chemical research; and this interest is mandated by advancements in all areas of industry and technology.
Abstract: The development of novel materials is a fundamental focal point of chemical research; and this interest is mandated by advancements in all areas of industry and technology. A good example of the synergism between scientific discovery and technological development is the electronics industry, where discoveries of new semiconducting materials resulted in the evolution from vacuum tubes to diodes and transistors, and eventually to miniature chips. The progression of this technology led to the development * To whom correspondence should be addressed. B.L.C.: (504) 2801385 (phone); (504) 280-3185 (fax); bcushing@uno.edu (e-mail). C.J.O.: (504)280-6846(phone);(504)280-3185(fax);coconnor@uno.edu (e-mail). 3893 Chem. Rev. 2004, 104, 3893−3946
2,621 citations