低温相变储能材料及其应用研究

利用相变储能材料（PCMs）潜热的热能存储（TES）是一种有效的热量利用方式。目前研究较多的储能材料包括无机体系（盐和水合盐）及有机化合物（石蜡、脂肪酸等）。本文对PCMs进行了归类并介绍了各类PCMs的基本特征;针对单纯的PCMs易泄漏的特点,介绍了多孔材料吸附PCMs形成复合PCMs及微胶囊封装技术;概括了PCMs在温度调控、热量储存等方面的应用;对目前PCMs的发展情况进行了总结,并对其未来的发展趋势进行了展望。     

静电纺丝用于制备有机相变储热纤维的研究进展

相变储热材料是指由于材料相转变吸热或放热过程而本身温度不变,从而实现储能的一类功能材料。有机相变材料如石蜡类、多元醇类及硬脂酸类因无腐蚀、无毒、无过冷等优点已成为重要的低温相变储热材料。这类材料通过固-液相变调节微环境温度,可用于服装、建筑及军事等方面,市场前景广阔。但相变过程易泄漏及热导率低等限制其了实际应用。静电纺丝是有效解决该问题的方法之一,高分子在高压静电作用下形成纤维,相变材料被高分子作为支撑材料所固定,很好地解决了泄漏问题。此外,通过加入高热导率材料可提高相变材料的吸放热速率,改善有机相变材料热导率低的问题。本文总结了近年来静电纺丝用于制备相变调温纤维的研究报道,分析了目前该类材料的研究现状,并讨论未来研究方向。为储热相变材料的进一步研究提供参考。     

金属有机框架及其衍生金属氧化物在锂和钠离子电池中的应用

高性能锂和钠离子电池是未来便携电子设备、电动汽车和大规模储能电站的重要组成部分,受到了各行业的广泛关注。目前商用的锂离子电池和研发中的钠离子电池都面临着一些技术瓶颈,主要表现为能量密度低、充放电慢等,导致无法满足市场的需求。具有独特结构、高比表面积的金属有机框架及其衍生金属氧化物可作为电化学储能器件新型电极材料,满足高性能锂和钠离子电池的要求。本文综述了近年来金属有机框架及其衍生金属氧化物作为锂和钠离子电池电极材料的研究进展,同时指出了金属有机框架及其衍生金属氧化物在实际应用中的不足及未来可能的一些改进措施。     

Conjugated carbonyl compounds as electrode materials for sodium-ion/potassium-ion batteries

钠（钾）离子电池资源丰富、成本低廉,是极具大规模应用潜力的新型电池体系。然而,受制于较大的钠（钾）离子半径,这两类电池电极材料的选择受到了极大的限制。以共轭羰基化合物为代表的有机电极材料具有柔性的骨架结构,对阳离子半径选择性小,且结构多样、理论比容量高、环境友好,基于有机共轭羰基化合物构建的钠（钾）离子电池是未来“绿色电池”发展的重要方向。本文介绍了共轭羰基化合物的分类、储钠/钾性能及机理,重点探讨了羰基化合物作为储钠（钾）材料存在的问题和改进方法。最后,总结了羰基化合物作为钠钾离子电池电极材料存在的基础科学问题、技术挑战以及竞争力,同时进一步展望了有机共轭羰基化合物的发展方向以及大规模储能领域的应用前景。     

超级电容器储能技术及其应用

超级电容器是近年发展起来的一种新型储能元件,具有功率密度高、寿命长、无需维护及充放电迅速等特性。叙述了超级电容器的分类、储能原理和性能特点,介绍了超级电容器目前的应用领域及应用中需要关注的问题。     

Application of Calix[4]quinone in secondary batteries

随着社会对大型储能设备的环保、充放电性能以及可持续发展的要求越来越高,基于金属氧化物的传统锂/钠离子电极材料受限于比容量,已难以满足未来储能系统的要求。有机材料、锂-硫/氧、液态流体等电池的研发与应用已成为未来能源系统研究的重要内容。其中,有机正极材料中的羰基类化合物Calix[4]quinone（C4Q）是一种很有前途的正极材料。该分子的空间位阻小,8个羰基结构都能发生可逆电极反应,其理论比容量高达446 mA·h/g,远超传统无机电极材料。C4Q不仅可以作为储锂材料,也可作为钠、锌、镁等二次电池的电极材料。本文分别介绍了C4Q在锂、钠二次电池和锌水系电池中的应用成果,并对C4Q今后进一步的开发利用做了展望。     

数据驱动的机器学习在电化学储能材料研究中的应用北大核心CSCD

储能电池的关键是材料。继实验观测、理论研究和计算模拟之后,数据驱动的机器学习具有快速捕捉材料成分-结构-工艺-性能间复杂构效关系的优势,有望为电化学储能材料的研发提供新的范式。本文从结构化和非结构化数据驱动两方面,系统评述了机器学习在电化学储能材料研究中的最新进展。全面概括了可用于电化学储能材料机器学习的国内外材料数据库,分析了其数据的收集、共享和质量检测存在的问题;重点阐述了电化学储能材料中机器学习的工作流程和应用,包括结构化数据驱动下数据收集、特征工程和机器学习建模以及图形、表征图像和文献文本这类非结构化数据驱动下的模型构建和应用。进一步,厘清电化学储能材料领域机器学习面临的三大矛盾且给出对策,即高维度与小样本数据的矛盾与协调、模型复杂性与易用性的矛盾与统一、模型学习结果与专家经验的矛盾与融合,并提出构建“领域知识嵌入的机器学习方法”有望调和这些矛盾。本文将为机器学习在电化学储能材料设计和性能优化中的应用提供参考。     

十水硫酸钠相变储能材料研究进展

十水硫酸钠(sodium sulfate decahydrate,SSD)具有适宜的相变温度(2.4℃)、较高的相变潜热值(大于200 J/g)、价格低廉、来源广和安全无毒等优点,是一种广受关注的无机水合盐相变材料.然而,在应用过程中存在过冷度大、相分离严重及泄漏等问题.本文综述了近年来解决上述问题的研究进展、共晶盐相变材料的制备及相关应用,并对后续的研究方向做了如下展望:在降低过冷度方面,采用硼砂、制备共晶盐或添加外场扰动的方式来改善过冷;在抑制相分离方面,采用高导热的多孔材料吸附相变材料,利用真空浸渍法制备定型相变材料的方法来改善或消除相分离现象;在共晶盐材料方面,可以绘制二元相图,寻找新型共晶相变材料进行研究,尤其是目前结合较少的有机相变材料;在应用方面,注重结合十水硫酸钠相变储能装置和系统进行研究并拓宽其应用范围.     

金属有机骨架及其衍生结构在锂硫电池中的应用

Li-S电池由于其高放电比容量(1 675 mAh/g)已被视为理想的储能系统之一.锂硫电池的巨大挑战是硫的利用率和锂金属枝晶等问题.金属有机骨架(MOFs)由于其具有可控的结构、高比表面积在锂硫电池中备受关注.主要论述了近几年国内外MOFs及其衍生结构材料在锂硫电池正极和隔膜中应用的研究进展,对合成方法、结构以及电化学性能等方面进行了相应的总结,并对目前存在的问题以及下一步的工作方向做出分析与展望.     

Progress of inorganic solid electrolyte for lithium ion batteries

目前,商品化的锂离子电池电解液主要以碳酸乙烯酯、碳酸二甲酯和碳酸甲乙酯等有机溶剂为溶剂,在电池使用过程中,存在电解液分解、锂枝晶生成和漏液等问题,从而影响电池的稳定性和安全性。无机固态锂电池电解质具有热稳定性高、电化学性能稳定、与高电压正极材料相容性好、安全性高及环境友好等优点,是目前储能领域研究的一个热点。研究和开发具有高离子电导率的无机固态电解质是促进其在电池中应用的关键和难点,本文综述了几类目前研究较多的LiPON型、钙钛矿型、石榴石型、LISICON型电解质,重点关注了其在离子电导率方面的研究及应用进展。     

The micro‐/nano‐PCMs for thermal energy storage systems: A state of art review

With advancement in technology—nanotechnology, various thermal energy storage (TES) materials have been invented and modified with promising thermal transport properties. Solid‐liquid phase change materials (PCMs) have been extensively used as TES materials for various energy applications due to their highly favourable thermal properties. The class of PCMs, organic phase change materials (OPCMs), has more potential and advantages over inorganic phase change materials (IPCMs), having high phase change enthalpy. However, OPCMs possess low thermal conductivity as well as density and suffer leakage during the melting phase. The encapsulation technologies (ie, micro and nano) of PCMs, with organic and inorganic materials, have a tendency to enhance the thermal conductivity, effective heat transfer, and leakage issues as TES materials. The encapsulation of PCMs involves several technologies to develop at both micro and nano levels, called micro‐encapsulated PCMs (micro‐PCM) and nano‐encapsulated PCMs (nano‐PCM), respectively. This study covers a wide range of preparation methods, thermal and morphological characteristics, stability, applications, and future perspective of micro‐/nano‐PCMs as TES materials. The potential applications, such as solar‐to‐thermal and electrical‐to‐thermal conversions, thermal management, building, textile, foam, medical industry of micro‐ and nano‐PCMs, are reviewed critically. Finally, this review paper highlights the emerging future research paths of micro‐/nano‐PCMs for thermal energy storage.     

Conduction paths of backbones for thermal enhancement of nanocomposite phase change materials

Thermal energy storage (TES) based on phase change materials (PCMs) has become a research hot spot due to its high energy storage density and maintained operating temperature during the phase change. However, as PCM has a poor thermal conductivity that can be as low as 0.2~0.5 W/m· K, the charging/discharging processes of PCM modules are significantly restrained, which severely affects the application of the TES technology in industrial sectors. This study concerns the improvement of the effective thermal conductivity of composite PCM formed by adding nanoparticles with high thermal conductivity into different PCMs. A theoretical model is established to reveal the intrinsic mechanism for the promotion of thermal conductivity of composite PCM consisting of nanoparticles. The results show that aggregation and interfacial thermal resistance are the main reasons for the change of the thermal conductivity. By forming effective conduction paths composed of backbones in the composite PCM, the average thermal conductivity can be improved significantly, which can be as high as 10~50 W/m· K with a wide range of volume fraction of the additives.     

Emerging applications of phase change materials: A concise review of recent advances

Phase change materials (PCMs) are used as latent heat thermal energy storage materials. The fields of application for PCMs are broad and diverse. Among these areas are thermal control of electronic components and thermal building regulations. These areas are used as heat and cold storage materials. The low thermal conductivity of PCMs is one of the significant and severe technological problems of PCMs. This paper presents a review of the latest works using PCMs in the thermal management of electronic components, buildings, and heat exchangers. Besides, it provides concise pieces of information on the classification of PCMs, their advantages, disadvantages, and thermal storage systems.     

Research progress on heat transfer enhancement technology of phase change energy storage

相变储能是通过相变材料吸/放热过程来实现能量储存的技术,它能够解决热量供需时间、空间和强度上的不匹配,并以其高储能密度成为储能领域的研究热点,但由于相变材料的热导率较低,使其应用受到限制。针对相变储能材料熔化/凝固过程中热导率低引起的传热速率慢的问题,从优化储能设备结构、添加剂提高相变材料热导率以及联合强化传热技术三方面综述国内外相变材料储能强化传热技术的最新进展。通过比较各种强化传热方式的优劣,实验和模拟均显示复合强化传热即可解决相变材料热导率低,又增大传热面积,从而提高相变材料的传热性能;多孔金属作为导热添加剂增强导热效果更好;并提出了相变储能强化传热技术未来需要解决的相关技术难题。     

Review of thermal energy storage for air conditioning systems

Thermal energy storage is very important to eradicate the discrepancy between energy supply and energy demand and to improve the energy efficiency of solar energy systems. Latent heat thermal energy storage (LHTES) is more useful than sensible energy storage due to the high storage capacity per unit volume/mass at nearly constant temperatures. This review presents the previous works on thermal energy storage used for air conditioning systems and the application of phase change materials (PCMs) in different parts of the air conditioning networks, air distribution network, chilled water network, microencapsulated slurries, thermal power and heat rejection of the absorption cooling. Recently, researchers studied the heat transfer enhancement of the thermal energy storage with PCMs because most phase change materials have low thermal conductivity, which causes a long time for charging and discharging process. It is expected that the design of latent heat thermal energy storage will reduce the cost and the volume of air conditioning systems and networks.     

Review of latent thermal energy storage systems for solar air-conditioning systems

Solar air conditioning is an important approach to satisfy the high demand for cooling given the global energy situation. The application of phase-change materials (PCMs) in a thermal storage system is a way to address temporary power problems of solar air-conditioning systems. This paper reviews the selection, strengthening, and application of PCMs and containers in latent thermal storage system for solar air-conditioning systems. The optimization of PCM container geometry is summarized and analyzed. The hybrid enhancement methods for PCMs and containers and the cost assessment of latent thermal storage system are discussed. The more effective heat transfer enhancement using PCMs was found to mainly involve micro-nano additives. Combinations of fins and nanoadditives, nanoparticles, and metal foam are the main hybrid strengthening method. However, the thermal storage effect of hybrid strengthening is not necessarily better than single strengthening. At the same time, the latent thermal storage unit has less application in the field of solar air-conditioning systems, especially regarding heat recovery, because of its cost and thermal storage time. The integration of latent thermal storage units and solar air-conditioning components, economic analysis of improvement technology, and quantitative studies on hybrid improvement are potential research directions in the future.     

金属基相变材料的研究进展及应用

金属基相变材料由于具有储能密度高、热稳定性好、热导率高等优点,在潜热热能储存系统中具有极大的优势。本文回顾了金属基相变材料的发展历程,归纳了金属基相变材料的性能参数,总结了各种热物性的测量方法,探讨了金属基相变材料与容器材料的相容性问题,分析了金属基相变材料在太阳能热发电、工业余热回收和电力削峰填谷中的应用前景。金属基相变材料的高温腐蚀性是目前限制其在热控制中应用的主要因素。为了实现金属基相变材料的广泛应用,需要重点解决金属基相变材料的封装问题。     

Development of the inorganic composite phase change materials for passive thermal management of Li-ion batteries: material characterization

The battery thermal management system based on phase change materials (PCMs) has proven to be a safe, inexpensive, and high-performance technology, which is currently gaining popularity over the other battery thermal management systems. PCMs are able to absorb heat generated by batteries, prolong battery life, and improve their performance. Organic compounds, such as paraffin, are widely used as phase change materials for the battery thermal management systems; however, there are no published data on the application of inorganic PCMs. Therefore, the main objective of this work is developing of two composite inorganic PCMs based on magnesium chloride hexahydrate and characterizing their properties for passive thermal control of lithium-ion battery packs. Moreover, to have a valid baseline and compare the behavior of two inorganic PCMs with currently commercialized and well investigated organic PCM, paraffin wax was used as reference material for both mixtures. All three PCMs were impregnated into the expanded graphite matrix to enhance their thermal conductivity. The material characterization studies, including thermal properties investigation, density and viscosity measurements, soaking and compression testing, evaluation of thermal expansion, thermal conductivity, and micro X-ray fluorescence analysis, were conducted for all PCMs. The results indicate that both inorganic mixtures are appropriate for thermal management of Li-ion battery packs. Future work with the developed and characterized composite inorganic PCMs will include electrical cycling studies and nail penetration tests to reveal their effectiveness for passive thermal management of Li-ion battery packs.     

固液相变蓄热技术的研究进展

综述了相变蓄热材料、相变传热问题求解方法、典型相变传热过程以及相变潜热蓄热系统(LHTES)优化设计及强化传热等诸多固液相变蓄热技术相关问题的研究进展情况