Yida Deng

Bio: Yida Deng is an academic researcher from Tianjin University. The author has contributed to research in topics: Nickel & Oxide. The author has an hindex of 9, co-authored 21 publications receiving 2404 citations. Previous affiliations of Yida Deng include Shanghai Jiao Tong University.

A review of electrolyte materials and compositions for electrochemical supercapacitors

Abstract: Electrolytes have been identified as some of the most influential components in the performance of electrochemical supercapacitors (ESs), which include: electrical double-layer capacitors, pseudocapacitors and hybrid supercapacitors. This paper reviews recent progress in the research and development of ES electrolytes. The electrolytes are classified into several categories, including: aqueous, organic, ionic liquids, solid-state or quasi-solid-state, as well as redox-active electrolytes. Effects of electrolyte properties on ES performance are discussed in detail. The principles and methods of designing and optimizing electrolytes for ES performance and application are highlighted through a comprehensive analysis of the literature. Interaction among the electrolytes, electro-active materials and inactive components (current collectors, binders, and separators) is discussed. The challenges in producing high-performing electrolytes are analyzed. Several possible research directions to overcome these challenges are proposed for future efforts, with the main aim of improving ESs' energy density without sacrificing existing advantages (e.g., a high power density and a long cycle-life) (507 references).

Sub-3 nm Co3O4 nanofilms with enhanced supercapacitor properties.

Abstract: Two-dimensional materials often show a range of intriguing electronic, catalytic, and optical properties that differ greatly from conventional nanoparticles. Herein, we demonstrate the large-scale preparation of sub-3 nm atomic layers Co3O4 nanofilms with a nonsurfactant and substrate-free hydrothermal method. This successful preparation of ultrathin nanofilms highlighted the reconstruction of cobalt-ammonia complexes and synergistic effect of free ammonia and nitrate on film growth control. Subsequent performance tests uncovered that these sub-3 nm atomic layer Co3O4 nanofilms exhibited an ultrahigh specific capacitance of 1400 F/g in the first galvanostatic charge/discharge test. The specific capacitance of Co3O4 nanofilms only slightly decayed less than 3% after 1500 cycling tests. With some parameter adjustments, similar Co(OH)2 nanofilms with a thickness of 3.70 ± 0.10 nm were also prepared. The Co(OH)2 nanofilms possessed maximum specific capacitance of 1076 F/g and peak performance attenuation of about 2% after a cycle stability test.

A Review of Electrolyte Materials and Compositions for Electrochemical Supercapacitors

Abstract: Electrolytes have been identified as some of the most influential components in the performance of electrochemical supercapacitors (ESs), which include: electrical double-layer capacitors, pseudocapacitors and hybrid supercapacitors. This paper reviews recent progress in the research and development of ES electrolytes. The electrolytes are classified into several categories, including: aqueous, organic, ionic liquids, solid-state or quasi-solid-state, as well as redox-active electrolytes. Effects of electrolyte properties on ES performance are discussed in detail. The principles and methods of designing and optimizing electrolytes for ES performance and application are highlighted through a comprehensive analysis of the literature. Interaction among the electrolytes, electro-active materials and inactive components (current collectors, binders, and separators) is discussed. The challenges in producing high-performing electrolytes are analyzed. Several possible research directions to overcome these challenges are proposed for future efforts, with the main aim of improving ESs' energy density without sacrificing existing advantages (e.g., a high power density and a long cycle-life) (507 references).

Shape-Controlled Synthesis of Palladium Single-Crystalline Nanoparticles: The Effect of HCl Oxidative Etching and Facet-Dependent Catalytic Properties

Abstract: This paper reports a convenient and facile preparation of single-crystalline palladium with controllable shape based on the reduction of kinetic control via hydrochloric acid oxidative etching. The concentration of HCl added to the reaction solution was found to be crucial for the shape evolution of palladium nanocrystals from nanocubes bounded by {100} facets to octahedrons by {111} facets. Palladium nanocubes can be readily obtained at a fast reduction rate without the involvement of additional HCl. With the introduction of a certain amount of HCl to the precursor solution, truncated nanocubes with {111} facets were formed, and the increase of HCl led to the slower reduction rate and the formation of palladium cuboctahedrons enclosed by six {100} facets and eight {111} facets at the expense of gradual shrinkage of {100} facets. The probable mechanism of morphological transformation was proposed upon a batch of experiments. The shape-dependent catalytic performances of as-obtained palladium nanocrystals ...

Microwave characterization of submicrometer-sized nickel hollow sphere composites

Abstract: In this work, we report on the microwave properties of the nickel hollow spheres (NHSs) synthesized by a facile autocatalytic reduction method. The resonance characterization of the NHS-polyvinyl butyral composite, due to the skin effect, is observed in the microwave frequency. It is shown that the resonant and the matching frequencies of the composite largely depend on the particle size of the spheres.

Electrochemical capacitors: mechanism, materials, systems, characterization and applications

Abstract: Electrochemical capacitors (i.e. supercapacitors) include electrochemical double-layer capacitors that depend on the charge storage of ion adsorption and pseudo-capacitors that are based on charge storage involving fast surface redox reactions. The energy storage capacities of supercapacitors are several orders of magnitude higher than those of conventional dielectric capacitors, but are much lower than those of secondary batteries. They typically have high power density, long cyclic stability and high safety, and thus can be considered as an alternative or complement to rechargeable batteries in applications that require high power delivery or fast energy harvesting. This article reviews the latest progress in supercapacitors in charge storage mechanisms, electrode materials, electrolyte materials, systems, characterization methods, and applications. In particular, the newly developed charge storage mechanism for intercalative pseudocapacitive behaviour, which bridges the gap between battery behaviour and conventional pseudocapacitive behaviour, is also clarified for comparison. Finally, the prospects and challenges associated with supercapacitors in practical applications are also discussed.

A review of electrolyte materials and compositions for electrochemical supercapacitors

Abstract: Electrolytes have been identified as some of the most influential components in the performance of electrochemical supercapacitors (ESs), which include: electrical double-layer capacitors, pseudocapacitors and hybrid supercapacitors. This paper reviews recent progress in the research and development of ES electrolytes. The electrolytes are classified into several categories, including: aqueous, organic, ionic liquids, solid-state or quasi-solid-state, as well as redox-active electrolytes. Effects of electrolyte properties on ES performance are discussed in detail. The principles and methods of designing and optimizing electrolytes for ES performance and application are highlighted through a comprehensive analysis of the literature. Interaction among the electrolytes, electro-active materials and inactive components (current collectors, binders, and separators) is discussed. The challenges in producing high-performing electrolytes are analyzed. Several possible research directions to overcome these challenges are proposed for future efforts, with the main aim of improving ESs' energy density without sacrificing existing advantages (e.g., a high power density and a long cycle-life) (507 references).

Ultracapacitors: Why, How, and Where is the Technology

Abstract: The science and technology of ultracapacitors are reviewed for a number of electrode materials, including carbon, mixed metal oxides, and conducting polymers. More work has been done using microporous carbons than with the other materials and most of the commercially available devices use carbon electrodes and an organic electrolytes. The energy density of these devices is 3¯5 Wh/kg with a power density of 300¯500 W/kg for high efficiency (90¯95%) charge/discharges. Projections of future developments using carbon indicate that energy densities of 10 Wh/kg or higher are likely with power densities of 1¯2 kW/kg. A key problem in the fabrication of these advanced devices is the bonding of the thin electrodes to a current collector such the contact resistance is less than 0.1 cm2. Special attention is given in the paper to comparing the power density characteristics of ultracapacitors and batteries. The comparisons should be made at the same charge/discharge efficiency.

Design and Mechanisms of Asymmetric Supercapacitors.

Abstract: Ongoing technological advances in diverse fields including portable electronics, transportation, and green energy are often hindered by the insufficient capability of energy-storage devices By taking advantage of two different electrode materials, asymmetric supercapacitors can extend their operating voltage window beyond the thermodynamic decomposition voltage of electrolytes while enabling a solution to the energy storage limitations of symmetric supercapacitors This review provides comprehensive knowledge to this field We first look at the essential energy-storage mechanisms and performance evaluation criteria for asymmetric supercapacitors to understand the wide-ranging research conducted in this area Then we move to the recent progress made for the design and fabrication of electrode materials and the overall structure of asymmetric supercapacitors in different categories We also highlight several key scientific challenges and present our perspectives on enhancing the electrochemical performance of future asymmetric supercapacitors