Carbon nanotubes for flexible energy storage devices--A review

碳纳米管具有本征sp²共价结构所带来的优异导电,导热及力学性能,并在锂电池,超级电容器等储能体系中具有广泛的应用前景.本文回顾了碳纳米管柔性储能的背景,介绍了碳纳米管优异的性能,独特的结构.这种一维的管状结构既可以作为柔性电极中的支撑骨架,也可以构建优越的长程导电网络,提供能源存储活性位点,进而提高柔性器件的性能.本文详细评述近年来碳纳米管在柔性超级电容器,锂离子电池,锂硫电池等能源存储元件应用中的一些最新进展和研究热点,其中柔性超级电容器,锂离子电池方面研究比较成熟,而锂硫电池尚在起步阶段,预期会取得快速进步.文章介绍了电极构建途径及性能评估方法,展示了碳纳米管基柔性储能器件的进展,并展望了其未来发展方向.     

Recent progress about graphene for chemical energy storage applications

石墨烯独特的二维空间结构使其具有优异的导电性能,力学性能以及超大的比表面积,被认为是颇具潜力的新型储能材料,是目前储能研究的热点之一.本文综述了石墨烯在储氢,超级电容器,锂离子电池,锂硫电池以及锂-空气电池等化学储能领域中的应用,探讨了不同制备方法对其性能的影响.石墨烯以其特殊的空间结构而成为极具前景的储氢材料,同时与其它材料复合后形成三维导电网络结构而提高电极材料的电化学性能,还可以缓冲电极材料在循环过程中的体积变化,有效提升储能材料的循环寿命.通过优化复合材料的微观结构,将进一步提高其电化学性能.本文最后就石墨烯在储能应用中的关键问题进行了简要分析.     

Application analysis and prospect of electrochemical energy storage in power grid

为促进能源产业的优化升级,可再生能源的开发利用力度不断加大,电网的规划运行和调度管理将面临重大变革,亟需先进的大规模储能技术来改善可再生能源发电特性。本文从电化学储能技术在电网系统应用进行探讨,从各种电化学储能安全性、成本、技术特点等进行深入解析,归纳各种类型电化学储能的优势与不足,并对未来电化学储能在电网系统的应用前景做出展望。     

Introducing the energy efficiency map of lithium‐ion batteries

The charge, discharge, and total energy efficiencies of lithium‐ion batteries (LIBs) are formulated based on the irreversible heat generated in LIBs, and the basics of the energy efficiency map of these batteries are established. This map consists of several constant energy efficiency curves in a graph, where the x‐axis is the battery capacity and the y‐axis is the battery charge/discharge rate (C‐rate). In order to introduce the energy efficiency map, the efficiency maps of typical LIB families with graphite/LiCoO₂, graphite/LiFePO₄, and graphite/LiMn₂O₄ anode/cathode are generated and illustrated in this paper. The methods of usage and applications of the developed efficiency map are also described. To show the application of the efficiency map, the effects of fast charging, nominal capacity, and chemistry of typical LIB families on their energy efficiency are studied using the generated maps. It is shown how energy saving can be achieved via energy efficiency maps. Overall, the energy efficiency map is introduced as a useful tool for engineers and researchers to choose LIBs with higher energy efficiency for any targeted applications. The developed map can be also used by energy systems designers to obtain accurate efficiency of LIBs when they incorporate these batteries into their energy systems.     

Graphene‐based ternary composites for supercapacitors

The research on electrode materials for supercapacitor application continues to evolve as the request of high‐energy storage system has increased globally due to the demand for energy consumption. Over the past decades, various types of carbon‐based materials have been employed as electrode materials for high‐performance supercapacitor application. Among them, graphene is 1 of the most widely used carbon‐based materials due to its excellent properties including high surface area and excellent conductivity. To exploit more of its interesting properties, graphene is tailored to produce graphene oxide and reduced graphene oxide to improve the dispersibility in water and easy to be incorporated with other materials to form binary composites or even ternary composites. Nowadays, ternary composites have attracted enormous interest as 2 materials (binary composites) cannot satisfy the requirement of the high‐performance supercapacitor. Thus, many approaches have been employed to fabricate ternary composites by combining 3 different types of electroactive materials for high‐performance supercapacitor application. This review focuses on the supercapacitive performance of graphene‐based ternary composites with different types of active materials, ie, conducting polymers, metal oxide, and other carbon‐based materials.     

Graphene‐wrapped poly(2,5‐dihydroxy‐1,4‐benzoquinone‐3,6‐methylene) nanoflowers as low‐cost and high‐performance cathode materials for sodium‐ion batteries

Graphene‐wrapped poly 2,5‐dihydroxy‐1,4‐benzoquinone‐3,6‐methylene (PDBM) nanocomposites with three‐dimensional nanoflower structures have been successfully prepared through the ultrasonic exfoliation and reassembly process in methanol. Compact distribution of graphene into the nanocomposite has established a three‐dimensional conductive network, which contributes to improved properties on discharge capacity and cycle performance. Composite with 20 wt% graphene was proved the best ratio when used in sodium‐ion batteries. Its initial discharge capacity can achieve 210 at 30 mA g^?1. After 100 cycles, the capacity is stable at 121 mAh g^?1. The composite featuring highly conductive channels and multidimensional electron transport pathway is synthesized by an easy ultrasonic way, which may be applied in large scales for sodium‐ion batteries.     

Compact energy storage: Opportunities and challenges of graphene for supercapacitors

碳纳米储能材料发展迅速,质量容量性能不断刷新。但通常碳纳米材料的密度较低,导致其体积比容量有限,在很多时候很难将材料水平上的优异性能反映到最终的器件上。发展高体积能量密度储能材料,在器件水平上实现致密储能,对推动储能材料和器件的实用化至关重要。作为其它sp2碳质材料的基本结构单元和一种柔性二维材料,石墨烯通过组装可以实现纳米结构致密化,在致密储能方面具有先天优势。本文以石墨烯在超级电容器中的应用为主,分别从材料、电极、器件3个层次讨论了实用化储能器件的设计原则,梳理了高体积能量密度碳基储能材料的研究进展,重点介绍了高体积容量碳电极材料的致密化设计理念,强调了从器件角度考虑储能材料设计的重要性,并对致密储能面临的机遇和挑战作了分析。     

Design and investigation on portable energy storage device based on sodium-ion batteries

报道了一种新型移动式钠离子电池储能系统,其核心储能器件为钠离子电池,采用自制的NaNi_1/3Fe_1/3Mn_1/3O₂为正极材料,负极材料为硬碳。采用XRD、DSC等对正极材料的结构和热稳定性进行分析表征。设计制作了1 A·h软包型钠离子电池,对其电化学性能与安全性进行测试。在此基础上设计了钠离子电池包以及基于钠离子电池的0.1 kW·h新型移动式储能系统。该系统在家用储能、军事电源、低速电动车上有良好的应用前景。     

A graphical model for evaluating the status of series‐connected lithium‐ion battery pack

State evaluation of battery pack is essential for battery management but laborious when dealing with massive information of cells within the pack. A graphical model for evaluating the status of series‐connected Li‐ion battery pack is established to release the burden. The model is founded by a 2D diagram, with the electric quantity “E” and the capacity “Q” as its axes, therefore called by the “E‐Q diagram.” The new graphical diagram presents the dynamics of cell variations in a linear way, thereby benefiting the design and management of battery pack, including (1) quantifying the cell variations by region, (2) illustrating the evolution of cell variations during aging, (3) guiding the estimation of pack states considering algorithm error in cell states, and (4) solving the balancing problem. The experimental results conform to the theoretical analysis, indicating that the E‐Q diagram will be pervasively applied in the design and management of series‐connected battery pack. Moreover, the E‐Q diagram is suitable for education on the basics of a battery pack, because it is a graphical model.     

A review of large‐scale electrical energy storage

This paper gives a broad overview of a plethora of energy storage technologies available on the large‐scale complimented with their capabilities conducted by a thorough literature survey. According to the capability graphs generated, thermal energy storage, flow batteries, lithium ion, sodium sulphur, compressed air energy storage, and pumped hydro storage are suitable for large‐scale storage in the order of 10's to 100's of MWh; metal air batteries have a high theoretical energy density equivalent to that of gasoline along with being cost efficient; compressed air energy storage has the lowest capital energy cost in comparison to other energy storage technologies; flywheels, super conducting magnetic storage, super capacitors, capacitors, and pumped hydro storage have very low energy density; compressed air energy storage, cryogenic energy storage, thermal energy storage, and batteries have relatively high energy density; high efficiencyin tandem with high energy density results in a cost efficient storage system; and power density pitted against energy density provides a clear demarcation between power and energy applications. This paper also provides a mathematical model for thermal energy storage as a battery. Furthermore, a comprehensive techno‐economic evaluation of the various energy storage technologies would assist in the development of an energy storage technology roadmap. Copyright © 2015 John Wiley & Sons, Ltd.     

储能与液流电池技术

大规模高效储能技术是解决可再生能源发电不连续、不稳定、不可控特性的重要途径,也是构建坚强智能电网的核心技术。本文对各种储能技术进行了综合分析,并对适用于大规模储能的抽水储能、压缩空气储能、钠硫电池、锂离子电池、铅酸电池和液流电池的技术特点、优劣势、发展前景进行了深入阐述;最后,对储能技术的发展思路进行了探讨,认为坚持技术开发与应用示范并重,进一步降低储能设备成本,提高其可靠性和稳定性并辅以一定的鼓励政策,是推进储能技术的产业化和实用化的重要途径。     

Characterization of metals and salts‐based thermal energy storage materials using energy balance method

Thermal energy storage technologies minimize the imbalance between energy production and demand. In this context, latent heat storage materials are of great importance as they have a higher density of energy storage as compared with the sensible heat storage materials. The present study involves the characterization of energy storage materials using an energy balance cooling curve analysis method. The method estimates the convective heat transfer coefficient in the solidification range to characterize the phase change materials for applications in energy storage. The method is more beneficial than the Computer Aided Cooling Curve analysis methods as it eliminates baseline calculations and the associated fitting errors. Metals (Sn) and salts (KNO₃ and NaNO ₃) were used in the present work. Phase change characteristics like the rate of cooling, liquidus and solidus temperatures, time for solidification, and enthalpy of phase change were estimated for both metals and salts. It was observed that the energy balance cooling curve analysis method worked very well for metals but not well suited for low conductivity salts. Salts could not be characterized since the thermal gradient existing within the salt sample was not considered in this method.     

Analysis for the applications of lithium titanate battery in the MW-class energy storage systems

相对于传统型的锂离子电池,钛酸锂电池具有充放电响应速度快、倍率特性好、寿命长等优点,但钛酸锂电池单位容量的成本较高。本文从储能系统应用需求层面分析典型功率型储能系统对电池倍率和容量的要求,结合钛酸锂电池的特点,得出高倍率的钛酸锂电池应用于功率型储能系统相对于能量型锂电池,可以大幅度减少电池配置数量的结论,因此可发挥钛酸锂电池的竞争优势。     

Grid to wheel energy efficiency analysis of battery‐ and fuel cell–powered vehicles

Sustainable energy consumption is an important part of the renewable energy economy as renewable energy generation and storage. Almost one‐third of the global energy consumption can be credited to the transportation of goods and people around the globe. To move towards a renewable energy–based economy, we must adopt to a more sustainable energy consumption pattern worldwide especially in the transportation sector. In this article, a comparison is being made between the energy efficiency of a fuel cell vehicle and a battery electric vehicle. A very simple yet logical approach has been followed to determine the overall energy required by each vehicle. Other factors that hinder the progress of fuel cell vehicle in market are also discussed. Additionally, the prospects of a hydrogen economy are also discussed in detail. The arguments raised in this article are based on physics, economic analyses, and laws of thermodynamics. It clearly shows that an “electric economy” makes far greater sense than a “hydrogen economy.” The main objective of this analysis is to determine the energy efficacy of battery‐powered vehicles as compared to fuel cell–powered vehicles.     

A hybrid lithium‐ion battery model for system‐level analyses

We describe an advanced lithium‐ion battery model for system‐level analyses such as electric vehicle fleet simulation or distributed energy storage applications. The model combines an empirical multi‐parameter model and an artificial neural network with particular emphasis on thermal effects such as battery internal heating. The model is fast and can accurately describe constant current charging and discharging of a battery cell at a variety of ambient temperatures. Comparison to a commonly used linear kilowatt‐hour counter battery model indicates that a linear model overestimates the usable capacity of a battery at low temperatures. We highlight the importance of including internal heating in a battery model at low temperatures, as more capacity is available when internal heating is taken into account. Copyright © 2016 John Wiley & Sons, Ltd.     

Research progress on cathode materials for high energy density lithium ion batteries

便携式电子设备的微型化、轻量化与电动汽车、电网储能设备的飞速发展,对高能量密度的锂离子电池的研发和性能表现提出了越来越高的要求。锂离子电池正极材料是锂离子电池的核心,其提供锂离子并参与电化学反应,因此改善正极材料性能是提高锂离子电池能量密度的关键。人们需要进一步研究开发成本较低、安全性更好的高能量密度新型锂离子电池正极材料。本文主要从提升正极材料的比容量和工作电压两方面介绍三元、富锂锰基材料和高电位镍锰酸锂等高比能量正极材料的介尺度结构设计、制备与性能调控研发进展。     

Progress in carbon fibers based flexible electrodes for supercapacitors

目前，环境友好的清洁能源的开发和设计是能源领域的研究重点。超级电容器是一种新型的储能器件，具有快速充放电的特点，在储能领域有很好的应用潜力。但是能量密度的不足，在一定程度上限制超级电容器的发展。另一方面，柔性电子器件的兴起要求储能器件必须也具备柔性的特质。因此，如何开发一个高能量密度，又同时保有高功率密度、长循环寿命特性的柔性超级电容器是研究人员致力解决的问题。目前常用的方法是将具有高理论比电容的赝电容材料和碳纤维柔性基底结合。本文结合本课题组在碳纤维基柔性超级电容器方面的探索，简单介绍超级电容器的存储机理和系统分类，综述了碳纤维基柔性超级电容器的研究情况和相应的柔性电极的制备方法。最后，讨论了碳纤维基柔性超级电容器在实际应用中的相关前景和挑战。     

Load‐frequency control of an interconnected hydro‐thermal power system with new area control error considering battery energy storage facility

This paper deals with load‐frequency control of an interconnected hydro‐thermal system considering battery energy storage (BES) system. A new area control error (ACEN) based on tie‐power deviation, frequency deviation, time error and inadvertent interchange (unscheduled energy transfer) is used for the control of the BES system. Time domain simulations are used to study the performance of the power system and the BES system. Results reveal that BES meets sudden requirements of real power load and is very effective in reducing the peak deviations of frequencies, tie‐power, time errors and inadvertent interchange accumulations. Copyright © 2000 John Wiley & Sons, Ltd.     

The patents analysis on supercapacitor energy storage

本文以超级电容器储能技术国际专利为研究对象,运用专利文献计量学方法,使用TDA和Innography专利检索与分析平台,对德温特专利数据库（DII）中收录的超级电容器储能技术相关专利的时序分布、来源国家和地区、技术主题、重点申请人等方面进行了分析,对超级电容器储能技术的国际发展现状、态势进行了梳理。     

Model‐based unscented Kalman filter observer design for lithium‐ion battery state of charge estimation

Accurate battery state‐of‐charge is essential for both driver notification and battery management units reliability in electric vehicle/hybrid electric vehicle. It is necessary to develop a robust state of charge (SOC) estimation approach to cope with nonlinear dynamic battery systems. This paper proposed an estimation method to identify the SOC online based on equivalent circuit battery model and unscented Kalman filter technique. Firstly, the parameters of dynamic battery model are identified offline and validated through typical electric vehicle road operation to guarantee its precision. Then the performance with respect to converge time, observer accuracy, robustness against system modeling errors, and mismatched initial SOC guess values is investigated. The accuracy of proposed estimation algorithm is validated under improved hybrid power pulse characterization test and New European Driving Cycle. Experiment and numerical simulation results clearly demonstrate that the proposed method is highly reliable with good robustness to different operating conditions and battery aging.