Design strategies of high-performance lead-free electroceramics for energy storage applications

A greater number of compact and reliable electrostatic capacitors are in demand due to the Internet of Things boom and rapidly growing complex and integrated electronic systems,continuously promoting the development of high-energy-density ceramic-based capacitors.Although significant successes have been achieved in obtaining high energy densities in lead-based ferroelectric ceramics,the utilization of lead-containing ceramies has been restricted due to environmental and health hazards of lead.Le...     

Polyphosphate based electrochemical capacitors

Environmentally friendly electrochemical capacitors (ECs) were assembled using hybrid materials formed by a polyphosphate gel matrix in which carbon-based materials were inserted and polyaniline were formed in a single-step synthesis. The hybrid materials were deposited on FTO glasses and symmetric ECs were assembled using a cellulose membrane soaked with an aqueous NaH₂PO₄ solution as a separator. The capacitance values were calculated from impedance spectroscopy and galvanostatic charge/discharge measurements. The devices showed capacitances ranging from 4.0 to 27.0 F cm^?3, which are comparable to some commercial devices. Better results were achieved in samples with polyaniline, which were ascribed to the pseudocapacitance impaired to the samples by the conducting polymer.     

RuOx/polypyrrole nanocomposite electrode for electrochemical capacitors

In this study, ruthenium oxide-polypyrrole (RuOx-PPy) composite nanostructures were prepared as electrode materials for electrochemical capacitors. Pyrrole was electrochemically polymerized in the pores of an anodized aluminum oxide (AAO) template. RuOx was further deposited on the surface of the PPy nanorod array by an electrochemical method. The morphology and composition of the RuOx-PPy nanocomposites were observed by SEM and EDX. The capacitive performance of the RuOx-PPy nanocomposites was investigated by the galvanostatic charge/discharge test as a function of the amount of RuOx. The maximum specific capacitance of the RuOx-PPy nanocomposite electrode was 419 mF cm^?2/681 F g^?1.     

Editorial for advanced energy storage and conversion materials and technologies

正With the rising demand for fast-charging technology in electric vehicles and portable devices,significant efforts have been devoted to the development of energy storage and conversion technologies.Nowadays,remarkable progress has been made in the field of various energy storage and conversion devices,i.e.,lithium-ion batteries (LIBs),lithium-metal batteries (LMBs),lithium-sulfur batteries(LSBs),sodium-ion batteries (SIBs),sodium-metal batteries (SMBs),magnesium-ion batteries (MIBs),zinc-ion batteries (ZIBs),electrochemical capacitors (ECs),the corresponding electrode materials have always been the focus and difficulty to further improve the electrochemical performance of the devices.     

Editorial for advanced energy storage and conversion materials and technologies

<正>Energy storage and conversion technologies have attracted increasing attention from academic and industrial communities due to the large demands from wide-ranging applications.Designing and developing high-performance electrode materials are cruciual to improve the performance of energy storage and conversion devices.At present,various energy storage and conversion devices,i.e.,potassium-ion batteries (PIBs),sodium-ion batteries     

碳纳米管-导电聚合物复合材料与电化学储能

介绍了本研究组近年在电化学合成碳纳米管-导电聚合物多孔复合材料薄膜及其电化学电容性能和材料结构方面的主要研究结果.酸氧化制备表面带羟、羧基团的碳纳米管中性或弱酸性悬浊液,在其中溶入导电聚合物单体后,视情况决定是否添加电解质电解,在阳极上共沉积出复合材料薄膜,其电化学电容超过3 F·cm-2(vs.电极表观面积).考察各种实验结果,提出5种纳米管-聚合物相互作用机理及其对改善材料电化学电容性能的贡献.     

Enhancing electrochemical performances of small quinone toward lithium and sodium energy storage

Further application of organic quinone cathodes is restricted because they are inherent in poor conductivity and tend to dissolve in aprotic electrolytes.Salinization can work on the strong solubility of quinones.Herein,the ortho-disodium salt of tetrahydroxyquinone(o-Na₂THBQ)was selected to promote the electrochemical properties of tetrahydroxyquinone(THBQ).Reduced dissolution of o-Na₂THBQ in electrolyte after salinization(replacement of two H with two Na)contributed to enhanced electrochemical performance.In sodium-ion batteries(SIBs)in ester-based electrolyte,o-Na2THBQ cathodes at 50 mA·g^-1exhibited a reversible discharge capacity of 107 mAh·g^-1after 200 cycles.Ulteriorly,in ether-based electrolyte,reversible discharge capacities of 200.4,102.2,99.5 and 88 mAh·g^-1were obtained at 800,1600,3200 and 4800 mA·g^-1after 1000,2000,5000 and 8000 cycles,respectively.The ultraviolet absorption spectra and ex situ dissolution experiments of THBQ and o-Na₂THBQ showed that o-Na₂THBQ hardly dissolved in ether-based electrolyte.In lithium-ion batteries(LIBs),graphene was selected to further enhance the conductivity of o-Na2THBQ.At 50 mA·g^-1,o-Na₂THBQ and o-Na₂THBQ/Gr cathodes exhibited reversible discharge capacities of 124 and 131.5 mAh·g^-1after 200 cycles in ester-based electrolyte,respectively.At 50 mA·g^-1,PTPAn/o-Na₂THBQ electrodes in an all-organic Na/Li-ion battery showed reversible charge/discharge capacities of 51/50.3 and 33.8/33.1 mAh·g^-1after 200 cycles.     

Nickel oxide/carbon nanotubes nanocomposite for electrochemical capacitance

We have fabricated supercapacitor electrodes with nickel oxide (NiO)/carbon nanotubes (CNTs) nanocomposite formed by a simple chemical precipitation method. The presence of CNT network in the NiO significantly improved (i) the electrical conductivity of the host NiO by the formation of conducting network of CNTs and (ii) the active sites for the redox reaction of the metal oxide by increasing its specific surface area. This increased the specific capacitance by 34% at a percolation limit of 10 wt.% of CNTs. In addition, we also found that the power density and cycle life were improved. We will further show that the specific surface area of the composite is closely related to the specific capacitance.     

Increasing the energy output of high-voltage pulse capacitors for downhole devices

Problems of increasing the specific energy output of high-voltage pulse capacitors for downhole electrical hydropulse devices are reviewed.     

Lithium-ion batteries for stationary energy storage

The use of Li-ion batteries for stationary energy storage systems to complement the renewable energy sources such as solar and wind power has recently attracted great interest. Currently available Li-ion battery electrode materials suitable for such stationary applications have been discussed, along with optimum cathode and anode combinations, limitations, and future research directions.     

V2CTx MXene and its derivatives:synthesis and recent progress in electrochemical energy storage applications

With the continuous development of two-di-mensional(2D)transition metal carbides and nitrides(collectively referred to as MXene).Nowadays,more than 70 MXene mat...     

Directions and materials challenges in high-performance photovoltaics

More efficient and higher performance photovoltaic solar cells continue to be developed for spacecraft power and are beginning to be developed for terrestrial concentrators. The need for high-efficiency and low-cost solar cells drives research into new materials and new materials applications. An overview of active areas of research into high-performance solar cells is presented in this article.     

Kinetically stabilized hydrogen storage materials

Kinetically stabilized hydrides are characterized by a low reaction enthalpy and a decomposition reaction that is thermodynamically favorable under ambient conditions. The rapid, low temperature hydrogen evolution rates offer much promise for mobile proton exchange membrane fuel cell applications. However, a critical challenge exists to develop new methods to regenerate or recycle the hydride directly from the reactants and hydrogen gas.     

A modified tool design for the drilling of high-performance aerospace materials

High-performance Ni- and Ti-based materials are generally difficult to machine. Drilling in particular is highly demanding for the applied tools due to challenging thermal stress. This paper describes a novel modification for twist drills which significantly improves the cooling and lubrication of the main and secondary cutting edges and leads to an enhancement in process productivity. Within the scope of this work, the achievable improvements with regard to wear progress, cutting edge temperature and cutting fluid flow when machining Inconel 718 are analysed. The solution developed could also prove its efficiency in the machining of titanium-based alloy Ti6Al4V.     

Decomposition kinetics of lithium amide for hydrogen storage materials

The kinetic behavior of LiNH₂ decomposition by ammonia release was quantified using thermogravimetric analysis (TGA). While not itself a hydrogen storage material, LiNH₂ is a primary component of the hydrided state in Li–N–H storage materials based on Li₃N or Li₂NH. Its decomposition by ammonia release, and consequent degradation of the hydrogen storage capacity, has important implications for the durability of Li–N–H storage systems. LiNH₂ from two commercial lots and one batch prepared at GM R&D were ball milled for 10 or 20 min to obtain fine LiNH₂ powders. Kinetic parameters were extracted from sets of TGA weight loss curves taken at different heating rates. The activation energy for the decomposition reaction was determined to be about 128 kJ/mole, virtually independent of the source and purity of the LiNH₂, its stoichiometry, ball milling time, and TGA sample size. The reaction rate was found to depend on the sample size as a consequence of the very low NH₃–LiNH₂ equilibrium vapor pressure at temperatures below 300 °C. Larger samples produce a local concentration of NH₃ high enough to inhibit further reaction. Direct isothermal measurements of the initial reaction rates at temperatures between 200 and 300 °C agree well with the values calculated from the heating rate-derived kinetic parameters. The durability of Li–N–H for hydrogen storage was estimated from the measured kinetic parameters by calculating the time required to decompose 20% of the initial LiNH₂, as a function of the operating temperature. The predicted lifetime falls below 10⁵ min for operating temperatures in excess of 160 °C.     

New composite thermoelectric materials for energy harvesting applications

The concept of using nanostructured composite materials to enhance the dimensionless thermoelectric figure of merit ZT relative to that for their counterpart homogeneous alloyed bulk crystalline materials of similar chemical composition is presented in general terms. Specific applications are made to the Si-Ge and Bi_2-−xSb_xTe₃ systems for use in high-temperature power generation and cooling applications. The scientific advantages of the nanocomposite approach for the simultaneous increase in the power factor and decrease in the thermal conductivity are emphasized insofar as their simultaneous occurrence is enabled by the independent control of these physical properties through the special properties of their nanostructures. Also emphasized are the practical advantages of using such bulk samples both for thermoelectric property measurements and for providing a straightforward path to scaling up the materials synthesis and integration of such nanostructured materials into practical thermoelectric powergeneration and cooling modules and devices.