锂离子电池低温快速加热方法研究进展

锂离子电池的性能直接影响电动汽车的续航、安全性和可靠性.低温环境下,锂离子电池功率特性变差、循环寿命衰减、可用容量降低,同时面临低温充电难、充电易析锂等问题,这些因素阻碍了电动汽车的发展.低温加热技术是电池热管理系统的核心技术之一,是缓解动力电池在低温环境下性能衰减的关键.本文综述了包括内部自加热法、MPH加热法、自加...     

低温环境下电池热管理研究进展

动力电池作为电动汽车（Electric vehicle, EV）的重要组件,在低温环境下存在能量密度和功率密度下降等问题。为提高低温条件下动力电池的性能,需要合适的电池热管理系统。本文介绍了动力电池在低温环境下的放电特性,整理归纳了现有的各种电池加热方式,并综述了低温环境下电池热管理研究进展,对电池低温下热管理的进一步研究具有指导意义。     

动力电池及充电基础设施技术发展对电动汽车能量补给方式的影响研究

电动汽车能量补给有两种典型模式—电池充电和电池更换,选择何种模式与动力电池的尺寸重量、能量密度、制造成本、电池管理系统及充电设施均有着密切的联系。对目前在国内外电动汽车上应用最广泛的磷酸铁锂和三元材料锂离子电池的发展水平进行了描述,同时分析了电动汽车充电和换电两种模式对电动汽车动力电池及充电基础设施等因素的要求,提出了电动汽车能量补给在何种条件下适合采用充电或换电模式的结论。     

锂离子电池低温复合加热策略及优化北大核心CSCD

电动汽车因为节能环保和能量转化效率高等特性在近年来发展迅速。在低温下,作为动力来源的锂离子电池的放电功率和容量等性能严重衰减,影响着电动汽车在北方极寒地区的发展和普及。因此,如何在低温下对锂离子电池进行可靠、高效、安全地低温加热显得尤为重要。以三元锂方块电池为研究对象,通过测试电池在不同工况下的低温特性,得出了电池电特性和热特性参数。建立单体电池低温电热耦合模型,通过神经网络方法拟合实验数据,得到电池低温加热仿真模型。通过电池不同工况下的温升实验,验证了仿真模型的精度。本文提出了电池多段恒流复合加热方法,建立了电池老化、加热时间、容量收益的多目标非线性优化模型,揭示了电池老化、加热时间和容量收益之间的关系,得到了评价加权权重矩阵。利用非支配排序遗传算法-Ⅱ(NSGA-Ⅱ)和优劣解距离法(TOPSIS),得到单体电池平衡加热策略,探究了电池不同初始状态对优化目标的影响规律。根据电池的不同初始状态以平衡加热策略为基础建立了单体电池加热电流数据库。电池初始温度为-20℃时,加热到10℃,所需加热时间为253 s,容量收益为4.72 Ah,电池老化为0.482‱,峰值功率收益为1104 W。     

Recent progress on thermal runaway propagation of lithium-ion battery

简述了电动汽车锂离子动力电池热失控蔓延机理、建模与抑制技术的最新研究进展。为了满足汽车高能量的要求,需要动力电池进行串并联成组来提供动力。电池组成组安全问题成为电动汽车大规模应用的重要技术问题。电池组中的某一个电池单体发生热失控后产生大量热,导致周围电池单体受热产生热失控。因而,电池组成组安全问题的重要关注点是电池组内的热失控蔓延问题。本文对锂离子电池热失控蔓延问题的国内外研究进展进行了综述,分析了对于不同种类锂离子动力电池影响其热失控蔓延特性的主要因素。总结了文献中的热失控蔓延建模方法,并指出了已有方法的不足。从电池系统热安全管理的角度,阐述并分析了热失控蔓延防控技术的研究成果与方向。最后对锂离子电池热失控蔓延研究进行了展望。     

车用锂电池工作特性研究

随着电动汽车产业的迅猛发展,电池技术越来越受到重视,研究动力电池的工作特性对合理使用、优化电池具有重要意义,可以提高电池能量利用率、延长使用寿命。针对电动汽车用锂离子电池工作特性进行研究,结果表明电池的充放电截止电压和拐点电压随温度变化而变化,而不受放电电流的影响。     

服役工况下车用锂离子动力电池散热方法综述

随着电动汽车的广泛使用,锂离子动力电池俨然成为纯电动汽车首选的动力来源,然而其热安全性问题也日益突出.基于此,本文针对车用锂离子动力电池在服役工况下尤其高温时存在的安全性差、工作不可靠及循环寿命短等热问题,根据电池的动态散热特性着重介绍了车用锂离子动力电池常用的冷却方法,包括空冷散热、液冷散热、相变材料冷却、热管冷却和耦合散热,说明了集多种冷却方式耦合的热管理系统与单一散热方法相比不仅能提高散热效率,还可以改善电池的均温性.并结合上述散热方法的研究进展及关键技术,主要在空冷通道优化、液冷结构设计及冷却液介质分析、相变材料应用特性、热管的冷却特性及热特性等方面进行了具体综述.最后,针对目前常用的动力电池散热方法中存在的问题提出了合理化建议,展望了电池热管理系统与汽车乘员热舒适性、电动机舱热管理及车辆热环境相耦合,形成整车热管理系统的开发,以期为电池热管理系统设计开发等相关领域的研究提供一定参考.     

废旧锂离子动力电池的性能和梯次利用的可能性研究

近年来随着电动汽车产业的发展,大量锂离子动力电池达到使用寿命,进入报废退役阶段,报废动力电池的处置成为人们关注的热点。综述了废旧锂离子动力电池的性能和梯次利用方面的技术进展,指出做好筛选分类与重新组合的工作,以确保二次利用电池组内部电池单元性能的同质性将是梯次利用的关键。     

Research and characterization of pulse charging strategy for lithium-ion traction battery

动力电池充电策略对提高电动汽车性能和使用寿命起着至关重要的作用。针对一种三元材料体系18650圆柱形电池进行脉冲充电策略研究,将其与标准恒流恒压充电策略进行综合比对,全面客观地分析脉冲充电策略关键参数对动力电池电性能的影响,并系统地评估了脉冲充电策略对电池寿命的影响。在循环寿命研究方面,采用电化学交流阻抗欧谱（EIS）分析不同循环周数和SOC下的交流阻抗,采用X射线断层扫描（CT）无损分析技术对循环500周后电池结构进行表征分析,揭示了带负脉冲充电策略对电池循环性能和结构影响的关系。     

锂离子电池BMS设计理论取得新进展

<正>锂离子电池已广泛应用于电动汽车、储能工程等国家战略新兴产业,受到学术界和工业界的广泛关注。在"十三五"规划期间,我国继续将"新能源汽车"列为国家重点研发计划的重点专项课题,对新能源汽车专用动力电池提出更高的要求。低成本、高容量、长寿命和高安全性的锂离子电池设计与制造是新能源汽车对于下一代动力电池提出的基本目标。电池管理系统(BMS)是新能源汽车动力系统总成     

Forecasting the value of battery electric vehicles compared to internal combustion engine vehicles: The influence of driving range and battery technology

Battery electric vehicles (BEVs) are now clearly a promising candidate to address the environmental problems that are associated with conventional internal combustion engine vehicles (ICEVs). Accordingly, governments in many countries have promoted consumer adoption of BEVs by providing financial incentives and automobile manufacturers are accelerating their efforts to develop BEVs. However, BEVs, unlike ICEVs, have not yet achieved mass market entry; continuing technological change is one way this barrier could be surmounted. The aim of this study is to assess and forecast whether and when design changes and technological improvements related to major challenges in driving range and battery cost will make the user value of BEVs greater than that of ICEVs. Specifically, we estimate the relative user value of BEVs and ICEVs resulting after design modifications are implemented to achieve different driving ranges by considering engineering trade-offs based on vehicle simulations. Then, we analyze when the BEV relative user value is expected to exceed that of ICEVs as energy density and cost of batteries improve due to ongoing technological changes. Our analysis demonstrates that the relative value of BEVs is lower than that of ICEVs because BEVs have high battery cost and high cost of time spent recharging them, despite featuring high torque, high fuel efficiency, and low fuel cost. Moreover, we found that the relative value differences between BEVs and ICEVs are found to be lower for high-performance large cars than low-performance compact cars because BEVs can achieve high acceleration performance more easily than can ICEVs. In addition, this study predicts that in approximately the year 2050, high-performance large BEVs could have a higher relative value than high-performance large ICEVs because of technological improvements in batteries; however, low-performance compact BEVs are still very likely to have significantly lower user values than will comparable ICEVs until well beyond the year 2050.     

Modeling the CO2 emissions from battery electric vehicles given the power generation mixes of different countries

With the number of vehicles on the world’s roads expected to grow to 2.9 billion by 2050, steps must be taken to reduce the CO₂ emissions from transport. Battery electric vehicles (BEVs) can help achieve this. This study aimed to determine the CO₂ emissions stemming from BEV operation in different countries and to compare those CO₂ emissions to the emissions from similar vehicles based on internal combustion engines (ICEs). This study selected four ICE-based vehicles, and modeled BEVs based on the specifications of each of these vehicles. The modeled BEVs were run through a simulation to determine their energy consumption. Their energy consumption was combined with data on the CO₂ intensity of the power generation mix in different countries to reveal the emissions resulting from BEV operation. The CO₂ emissions from the BEVs were compared to the CO₂ emissions for their ICE-based counterparts. Amongst the results, it was shown that for China and India, and other countries with a similarly high CO₂ intensity, unless power generation becomes dramatically less CO₂ intensive, BEVs will not be able to deliver a meaningful decrease in CO₂ emissions and an increase in the penetration of BEVs could actually lead to higher CO₂ emissions.     

Environmental impacts of the infrastructure for district heating in urban neighbourhoods

District heating is a technology for distributing centrally produced heat for space heating and sanitary hot-water generation for residential and commercial uses. The objectives are to identify which subsystems and components of a district heating grid are the main contributors to the overall impact of the infrastructure; and provide environmentally oriented design strategies for the future eco-redesign of these kinds of infrastructures. This paper performs a life-cycle assessment (LCA) to determine the environmental impacts of a district heating infrastructure in an urban neighbourhood context. The analysis covers seven subsystems (power plant, main grid, auxiliary components of the main grid, trench works, service pipes, buildings and dwellings) and twelve standard components. The results for the subsystems show that the sources of impact are not particularly located in the main grid (less than 7.1% contribution in all impact categories), which is the focus of attention in the literature, but in the power plants and dwelling components. These two subsystems together contribute from 40% to 92% to the overall impact depending on the impact categories. Concerning the components, only a reduced number are responsible for the majority of the environmental impact. This facilitates identifying effective strategies for the redesign of the infrastructure.     

Primary energy efficiency of alternative powertrains in vehicles

This study considers the technical potential concerning the energy efficiency attainable for vehicles with alternative powertrains within 10–20 years. The potential for electric vehicles (BEVs), hybrid electric vehicles (HEVs) and fuel-cell electric vehicles (FCEVs) is assessed and compared with the potential improvement in conventional vehicles with internal combustion engines (ICEVs). Primary energy efficiency is the measure used in this study for comparison. The calculations of primary energy efficiency are based on three different resources: fossil fuels, biomass, and primary electricity from wind, solar or hydropower. This study shows that there is potential for doubling the primary energy efficiency using alternative powertrains in vehicles such as BEVs, HEVs and FCEVs, compared with existing ICEVs. All vehicles with an alternative powertrain have a higher potential for primary energy efficiency than vehicles with an improved conventional powertrain. No “winner” amongst the alternative powertrains could be identified from a primary energy efficiency point of view.     

基于计算机仿真的低温地板辐射采暖系统的节能性分析

介绍了基于空间热网模型的采暖系统的计算机仿真程序，并运用该程序对低温地板辐射采暖和对流采暖两种系统进行计算机仿真，通过对一个采暖日内两种采暖方式下房间的采暖负荷、室内平均空气温度和维护结构内表面温度的动态分析和比较，证明了在维持房间相同热舒适度的情况下，低温地板辐射采暖系统的采暖负荷比对流采暖系统的采暖负荷小，具有节能性。     

Life cycle cost of conventional,battery electric,and fuel cell electric vehicles considering traffic and environmental policies in China

Electric vehicles (EVs) are considered a promising alternative to conventional vehicles (CVs) to alleviate the oil crisis and reduce urban air pollution and carbon emissions. Consumers usually focus on the tangible cost when choosing an EV or CV but overlook the time cost for restricting purchase or driving and the environmental cost from gas emissions, falling to have a comprehensive understanding of the economic competitiveness of CVs and EVs. In this study, a life cycle cost model for vehicles is conducted to express traffic and environmental policies in monetary terms, which are called intangible cost and external cost, respectively. Battery electric vehicles (BEVs), fuel cell electric vehicles (FCEVs), and CVs are compared in four first-tier, four new first-tier, and 4 s-tier and below cities in China. The comparison shows that BEVs and FCEVs in most cities are incomparable with CVs in terms of tangible cost. However, the prominent traffic and environmental policies in first-tier cities, especially in Beijing and Shanghai, greatly increase the intangible and external costs of CVs, making consumers more inclined to purchase BEVs and FCEVs. The main policy benefits of BEVs and FCEVs come from three aspects: government subsidies, purchase and driving restrictions, and environmental taxes. With the predictable reduction in government subsidies, traffic and environmental policies present important factors influencing the competitiveness of BEVs and FCEVs. In first-tier cities, BEVs and FCEVs already have a competitive foundation for large-scale promotion. In new first-tier and second-tier and below cities, stricter traffic and environmental policies need to be formulated to offset the negative impact of the reduction in government subsidies on the competitiveness of BEVs and FCEVs. Additionally, a sensitivity analysis reveals that increasing the mileage and reducing fuel prices can significantly improve the competitiveness of BEVs and FCEVs, respectively.     

Low-temperature geothermal utilization in Iceland – Decades of experience

Geothermal energy plays a key role in the economy of Iceland and it supplies about 89% of the space heating requirements. A large fraction of the country's district heating services (hitaveitas) use energy from low-temperature geothermal systems, which are mostly located outside the volcanic zone. Many of the geothermal district heating services have been in operation for several decades and much can be learned from their operation, in particular regarding long-term management of low-temperature geothermal resources. In most cases down-hole pumps are used, but there are examples of large-scale artesian flow still being maintained. The Reykjavík geothermal district heating service is the world's largest such service. It started operation on a small scale in 1930, and today it serves Reykjavík and surrounding communities, about 58% of the total population of Iceland. The Reykjavík district heating service utilizes three low-temperature systems. The production and response (pressure, chemistry, and temperature) histories of these systems and six other low-temperature geothermal systems are discussed. Four of the systems are very productive and reach equilibrium at constant production. Two are much less productive and do not attain equilibrium, while three are of intermediate productivity. Groundwater inflow has caused temperature decline and chemical changes in two of the systems. Several problems have faced the Icelandic low-temperature operations, such as excessive pressure drawdown caused by overexploitation, colder water inflow, and sea water incursion. None of the district heating systems has ceased operation and solutions have been found to these problems. The solutions include improving the energy efficiency of the associated heating systems, deeper and more focussed drilling (e.g., directional drilling), finding new drilling targets (even new drilling areas), and injection, as well as technical solutions on the surface. The long utilization case histories provide important information pertaining to sustainable management of geothermal resources.     

对我国发展纯电动汽车的质疑与思考

近年来国家对纯电动汽车的扶持力度正在不断加大。然而纯电动汽车、混合动力汽车等以电力作燃料,并非真正意义上的新能源汽车。纯电动汽车所消耗的电力需要由发电厂提供,相当于以煤代油,其外部负效应表现在燃煤电厂的负效应上。燃油汽车和纯电动汽车每辆车每年的能耗折算成标煤分别为1.53t和1.6t,基本上相等,但燃油排放的二氧化碳比燃煤少,所以纯电动汽车并不是低碳汽车。用纯电动汽车替代燃油汽车,很可能是减少了石油进口,但却要增加煤炭进口,并不能从根本上提高我国能源的安全性。发展纯电动汽车需要大量投资,再加上环境污染,经济性很差。鉴于此,建议我国应重新定义新能源汽车,要真正利用新能源作为汽车的动力,寻找适合我国能源资源条件的真正的新能源汽车或替代能源汽车;中国在相当长的时间里节能减排还是主要依靠传统燃油汽车,在重视研发新能源汽车、研究替代燃油汽车的同时,应重视传统燃油汽车的节能降耗;控制汽车消费是最有效的节油措施;节能减排必须要从一次能源算起,我国电源结构以煤电为主,并不适宜发展纯电动汽车。中国要等到第一次和第二次能源大转换完成之后,当天然气、水电、核电在电源结构中占据主体地位时,纯电动汽车才会有广阔的发展前景。     

A feasibility study on solar-wall systems for domestic heating – An affordable solution for fuel poverty

A Solar Wall Heating (SWH) system was developed to provide low cost space heating in traditional solid stone-walled tenement buildings in Scotland. The SWH system uses the internal solid walls to store the solar heat collected during the day and heat the bedrooms during the night.A physical laboratory model with attached solar hot water system and a computational model of it were developed to investigate the dynamic performance of the system in use and test the cost benefits of iterations of its modes of use. The temperatures throughout the wall structure were measured under the variant solar input of a 24-h cycle. An unsteady state CFD model was developed and validated using the measured data and setup to test a number of key variables of the solar wall heating system in use. These included optimisation control strategies and maximisation strategies for the collection and storage of solar heat under various conditions. This paper presents the modelled results of the solar thermal storage and optimisation system and strategies for internal solid stone walls in a typical Scottish tenement flat in the Scottish climate.In addition the study analysed the solar availability, heating demand and domestic water supply of two typical dwellings based on two reliable methods: (a) a purpose built dynamic thermal model and (b) data collected in previous studies.The study demonstrated that the solar collection of current solar hot water systems can be improved upon so that, even in Scotland, more solar power can be harvested to contribute not only to domestic hot water, but also domestic space heating, particularly in buildings occupied over 24 h with heavy thermal mass. The cost analysis of the system in use suggested a 16 year payback period for such a system for a tenement flat.     

On the robustness, effectiveness and reliability of chemical and mechanical heat pumps for low-temperature heat source district heating: A comparative simulation-based analysis and evaluation

Our physical environment is endowed with unlimited amount of natural and artificial sources of energy at various low exergetic levels which leaves them almost impossible to be thermally utilized at such source states. The thermal upgrading of these low exergetic energy sources could render them amenable to various practical thermal usages. This paper provides a comparative study through simulations, of the effectiveness, robustness and reliability of the often two most promising heat upgrading technologies (the chemical and mechanical heat pumps) systems for the sustainable heat upgrading of low-temperature heat sources for district heating. The simulation results reveal that for a low to medium energy demand, low-temperature heat source upgrading using the chemical heat pumps seems more promising than the mechanical heat pumps, while the mechanical heat pump is best suited for high energy demand space heating. In the simulation, use was made of an artificial low-temperature heat source (a nearby pharmaceutical industry waste heat) with source temperature state of between 25 and 35 °C as the feed to the upgrading units. The high energy demand (assumed to be able to serve the space heating energy requirements of a given locality) was estimated to be 923 TJ/annum at a consumer-side temperature level of about 95 °C.

The selected most robust system (the mechanical heat pump-based process) for upgrading the low-temperature heat source at such given high energy demand has been conceptually designed.