Active MgH2?Mg Systems for Reversible Chemical Energy Storage

An overview of the importance of and methods available for heat storage in the form of sensible and latent heat is followed by a discussion of the advantages and disadvantages of reversible thermochemical energy storage compared to conventional energy sources such as fuels, i.e. irreversible chemical energy carriers. Of the reversible metal-hydride–metal systems, the MgH₂? Mg system is particularly attractive as a hydrogen and a high-temperature heat storage material because of its high hydrogen content and the high energy content of the Mg–H bond. The advances made in this area over the past few years, namely in catalytic hydrogenation and the doping of magnesium powders, have led to the development of “active MgH₂? Mg systems” for energy storage. The first experimental results on high-temperature heat storage (also with cooling) by coupling a MgH₂? Mg storage system with a low-temperature metal hydride storage system are presented.     

Maximizing the Solar Energy Storage of the Norbornadiene-Quadricyclane System: Mono-Heteroatom Effect by DFT Calculations

An attempt was made to maximize the solar energy storage in a norbornadiene (1)/quadricyclane (2) system, through the angling of mono-heteroatoms at C₁, C₂, or C₇ atoms of 1 and 2 and calculating the corresponding energies at the B3LYP/6-311++G(3df,2p) level of theory. Free energy gaps between 1 _nX and 2 _nX, Δ G_{(1nx) ? (2nx)}, as well as solar energy storage was the most for 1 _1As (–24.20),1 _2N (–32.48), and 1 _7As (–29.77) in kcalmol^?1 from group V of the Periodic Table.     

Tuning of the properties of rhodopsin-based molecular switches

The modification of relevant chemical properties of rhodopsin-based molecular photoswitches is presented. We show how both the substituents present and the nitrogen atom quaternization are capable to change the wavelength of absorption and the thermal stability of the photoisomer. Adjusting these properties, the molecular switches could be turned into useful compounds for solar energy storage devices.     

Selective Water Sorbents for Multiple Applications, 10. Energy Storage Ability

The application of new selective water sorbents for storage of low temperature heat is analyzed. Values of energy storage ability E are measured by a DSC technique for more than fifteen samples of selective water sorbents based on silica gels, aluminas, carbon Sibunit and aerogels as host matrices and CaCl₂, LiBr, MgCl₂ as impregnated salts. E-values up to 8.4 kJ/g and 4.0 kJ/g are found for forced and naturally saturated sorbents, which are much higher than for common sorbents, like zeolites and unimpregnated silica gels. The temperature dependence of E gives an estimation of sensible and latent heat contributions as well as the average heat of water desorption and average specific heat of dry sorbents. A comparison between the SWSs and others materials proposed in literature is done.     

Preparation and Characterization of Microencapsulated Hexadecane Used for Thermal Energy Storage

Polyurea microcapsules about 2.5μm in diameter containing phase change material for thermal energy storage application were synthesized and characterized by interfacial polycondensation method with toluene-2,4-diisocyanate and ethylenediamine as monomers in an emulsion system. Hexadecane was used as a phase change material and OP, which is nonionic surfactant, and used as an emulsifier. The chemical structure and thermal behavior of the microcapsules were investigated by FTIR and thermal analysis respectively. The results show encapsulated hexadecane has a good potential as a solar energy storage material.     

High‐Capacity Anode Materials for Sodium‐Ion Batteries

Na‐ion batteries are an attractive alternative to Li‐ion batteries for large‐scale energy storage systems because of their low cost and the abundant Na resources. This Review provides a comprehensive overview of selected anode materials with high reversible capacities that can increase the energy density of Na‐ion batteries. Moreover, we discuss the reaction and failure mechanisms of those anode materials with a view to suggesting promising strategies for improving their electrochemical performance.     

相变储能材料的研究进展

综述了相变材料的研究进展状况 ,介绍了相变材料的分类以及各类相变材料的性能、储能机理和优缺点 ,并介绍了一些新型的相变材料 ,指出了该领域中有待解决的问题 ,展望了未来相变材料的发展前景。     

Conversion of Solar Energy to Fuels by Inorganic Heterogeneous Systems

Over the last several years,the need to find clean and renewable energy sources has increased rapidly because current fossil fuels will not only eventually be depleted,but their continuous combustion leads to a dramatic increase in the carbon dioxide amount in atmosphere.Utilisation of the Sun’s radiation can provide a solution to both problems.Hydrogen fuel can be generated by using solar energy to split water,and liquid fuels can be produced via direct CO2 photoreduction.This would create an essentially free carbon or at least carbon neutral energy cycle.In this tutorial review,the current progress in fuels’ generation directly driven by solar energy is summarised.Fundamental mechanisms are discussed with suggestions for future research.     

Combining experimental and computational methods to unravel the dynamical structure of photoelectrosynthetic interfaces

At photoelectrosynthetic interfaces, an electrochemical reaction is driven by excited charge carriers from a semiconducting photoabsorber. The structure and composition of this interface determine both the electronic and electrochemical performance of devices, yet this structure is often highly dynamic both in the time-domain and upon applied potentials. We discuss the arising challenges from this dynamical nature and review recent approaches to gain an atomistic understanding of the involved processes, which increasingly involves a combination of experimental and computational methods. Bearing a similarity to solid-electrolyte interphase formation in batteries, their apprehension could help to develop functional passivation layers for high-performance photoelectrosynthetic devices.     

Towards Solar Energy Storage in the Photochromic Dihydroazulene–Vinylheptafulvene System

One key challenge in the field of exploitation of solar energy is to store the energy and make it available on demand. One possibility is to use photochromic molecules that undergo light‐induced isomerization to metastable isomers. Here we present efforts to develop solar thermal energy storage systems based on the dihydroazulene (DHA)/vinylheptafulvene (VHF) photo/thermoswitch. New DHA derivatives with one electron‐withdrawing cyano group at position 1 and one or two phenyl substituents in the five‐membered ring were prepared by using different synthetic routes. In particular, a diastereoselective reductive removal of one cyano group from DHAs incorporating two cyano groups at position 1 turned out to be most effective. Quantum chemical calculations reveal that the structural modifications provide two benefits relative to DHAs with two cyano groups at position 1: 1) The DHA–VHF energy difference is increased (i.e., higher energy capacity of metastable VHF isomer); 2) the Gibbs free energy of activation is increased for the energy‐releasing VHF to DHA back‐reaction. In fact, experimentally, these new derivatives were so reluctant to undergo the back‐reaction at room temperature that they practically behaved as DHA to VHF one‐way switches. Although lifetimes of years are at first attractive, which offers the ultimate control of energy release, for a real device it must of course be possible to trigger the back‐reaction, which calls for further iterations in the future.     

Holographic Methods for the Investigation of Photochemical and Photophysical Properties of Molecules

Holography is most frequently thought of as a method of photography that results in three-dimensional images of the object being photographed. It is certainly true that this is the most visually spectacular aspect. But holography can also be used as a powerful tool for the investigation of a variety of photochemical and photophysical processes. These experimental techniques rely on the fact that small spatial modulations of a material's optical properties (index of refraction and absorption coefficient) can deflect an incident light beam into another direction. By following the growth or decay in intensity of this deflected beam, one can follow the underlying photochemical and photophysical processes producing the changes in optical properties. If a CW laser is used to produce the hologram one can use the technique to investigate solid state photochemistry. If a pulsed laser is used one can investigate a broad range of time dependent processes; energy transfer, diffusion, rotational relaxation, charge transport etc. Compared to conventional spectroscopic techniques the holographic method shows various advantages. So for example it is a highly sensitive zero-background technique and permits free choice of detection wavelength and detection beam intensity. As a result of information obtained using the holographic technique as a scientific tool, one can also find new classes of materials for the recording of holograms. This is the way in which two-photon four-level systems for hologram recording process gated on and off with an auxiliary source, and can be read with the infrared recording laser with no erasing of the hologram.     

硅烷接枝聚乙烯储存稳定性的研究

利用熔体流动速率测定仪进行了硅烷接枝聚乙烯的水解缩合交联反应的加速试验,发现该反应对水分浓度为一级反应,反应的表现活化能４２ｋＪ／ｍｏｌ,由此可推算Ａ组份的保存期。当催化剂存在时,水解缩合反应明显加快,这时的表观活化能降到２０ｋＪ／ｍｏｌ。     

Microencapsulation of n-Eicosane as Energy Storage Material

For heat energy storage application, polynrea microcapsules containing phase change material, n-eicosane, were synthesized by using interfacial polymerization method with toluene-2,4-diisocyanate (TDI) and diethylenetriamine(DETA) as monomers in an emulsion system. Poly(ethylene glycol)octyl-phenyl ether (OP), a nonionic surfactant,was the emulsifier for the system. The experimental result indicates that TDI was reacted with DETA in a mass ratio of 3 to 1. FF-IR spectra confirm the formation of wall material, polyurea, from the two monomers, TDI and DETA.Encapsulation efficiency of n-eicosane is about 75%. Microcapsule of n-eicosane melts at a temperature close to that of n-eicosane, while its stored heat energy varies with core material n-eicosane when wall material fixed.Thermo-gravimetric analysis shows that core material n-eicosane, micro-n-eicosane and wall material polyurea can withstand temperatures up to 130, 170 and 250℃, respectively.     

Integrated Devices to Realize Energy Conversion and Storage Simultaneously

Other forms of energy are generally converted to electric energy and then transported to electrochemical devices, where the energy is stored, by external electric wires. To further improve total energy conversion and storage efficiency, interest in simultaneously realize the energy conversion and storage in a single device has increased. This Concept describes recent progress in developing such novel integrated energy devices. Both planar and wire architectures are carefully illustrated with an emphasis on the “energy wire” which has been the focus of past developments due to its unique and promising applications, such as being woven into clothes or other complex structures by conventional textile technology. The current challenges and future directions of the integrated devices, particularly in the wire architecture, are summarized.     

可规模储能的沉积型单液流电池研究进展

与全钒等双液流电池相比,沉积型单液流电池不使用离子交换膜等昂贵材料,结构简化,比能量提高,适合于不同规模的储能场合,研究渐多.本文介绍了沉积型单液流电池的原理与特点及其结构组成,以笔者实验室工作为主,综述了各沉积型单液流电池新体系的研究进展及存在的问题,并指出目前单液流电池待解决的问题是高比容量、高稳定性电极材料和电堆...     

Confined‐Volume Effect on the Thermal Properties of Encapsulated Phase Change Materials for Thermal Energy Storage

We have encapsulated the heat exchange material, n‐docosane, into polyurethane capsules of different sizes. Decreasing the size of the capsules leads to changes of the crystallinity of phase‐change material as well as melting/crystallization temperature. The novelty of the paper includes 1) protection of the nanostructured energy‐enriched materials against environment during storage and controlled release of the encapsulated energy on demand and 2) study of the structure and surface‐to‐volume properties of the energy‐enriched materials dispersed in capsules of different sizes. The stability of energy nanomaterials, influence of capsule diameter on their energy capacity, homogeneity and operation lifetime are investigated.     

A General Strategy Towards Encapsulation of Nanoparticles in Sandwiched Graphene Sheets and the Synergic Effect on Energy Storage

A novel and universal approach towards the unique encapsulation of nanoparticles in the sandwiched graphene sheets is presented here. In the method, a low‐cost, sustainable and environmentally friendly carbon source, glucose, is firstly applied to yield the high‐quality, uniform and coupled graphene sheets in a large scale, and the pre‐fabricated hydrated nanosheets act as the sacrificial templates to generate the enveloped metallic nanoparticles. After controllable oxidation or removal of the encapsulated nanoparticles, sandwiched nanocomposite with oxidizes nanoparticles encapsulated in graphene sheets or pure phase of sandwich‐like and coupled graphene sheets would be achieved. Moreover, the synergic effect on energy storage via Li‐ion batteries is solidly verified in the Co₃O₄@graphene nanocomposite. More importantly, the unique structure of the nanoparticles‐encapsulated sandwiched graphene sheets will definitely result in additional applications, such as biosensors, supercapacitors and specific catalyses. These results have enriched the family of graphene‐based materials and recognized some new graphene derivatives, which will be considerably meaningful in chemistry and materials sciences.     

Aromaticity‐Controlled Energy Storage Capacity of the Dihydroazulene‐Vinylheptafulvene Photochromic System

Photochemical conversion of molecules into high‐energy isomers that, after a stimulus, return to the original isomer presents a closed‐cycle of light‐harvesting, energy storage, and release. One challenge is to achieve a sufficiently high energy storage capacity. Here, we present efforts to tune the dihydroazulene/vinylheptafulvene (DHA/VHF) couple through loss/gain of aromaticity. Two derivatives were prepared, one with aromatic stabilization of DHA and the second of VHF. The consequences for the switching properties were elucidated. For the first type, sigmatropic rearrangements of DHA occurred upon irradiation. Formation of a VHF complex could be induced by a Lewis acid, but addition of H₂O resulted in immediate regeneration of DHA. For the second type, the VHF was too stable to convert into DHA. Calculations support the results and provide new targets. We predict that by removing one of the two CN groups at C‐1 of the aromatic DHA, the heat storage capacity will be further increased, as will the life‐time of the VHF. Calculations also reveal that a CN group at the fulvene ring retards the back‐reaction, and we show synthetically that it can be introduced regioselectively.     

钙钛矿型稀土氧化物的合成及其能源转化储存应用研究进展

钙钛矿型稀土氧化物价格低廉、结构可控、性质多样,在催化领域有着广阔的应用前景。本文从钙钛矿型稀土氧化物的结构类型、合成方法及电化学催化反应出发,总结了传统高温合成方法、火焰喷雾法、静电纺丝法和脉冲激光沉积法等几种最常用的合成方法,以及提升其氧析出反应(OER),氢析出反应(HER)和氧还原反应(ORR)催化能力的典型有效方法,概述了近年来钙钛矿型稀土氧化物在电解水、金属空气电池和固体氧化物燃料电池等能源转化储存装置的主要研究进展,进而对钙钛矿型稀土氧化物在能源转化储存领域的应用进行了展望。