Photoinduced Cu^(+)/Cu^(2+)interconversion for enhancing energy conversion and storage performances of CuO based Li-ion battery

Pursuing appropriate photo-active Li-ion storage materials and understanding their basic energy storage/conversion principle are pretty crucial for the rapidly developing photoassisted Li-ion batteries(PA-LIBs).Copper oxide(CuO)is one of the most popular candidates in both LIBs and photocatalysis.While CuO based PA-LIBs have never been reported yet.Herein,one-dimensional(1D)CuO nanowire arrays in situ grown on a three-dimensional(3D)copper foam support were employed as dualfunctional photoanode for both‘solar-to-electricity’and‘electricity-to-chemical’energy conversion in the PA-LIBs.It is found that light energy can be indeed stored and converted into electrical energy through the assembled CuO based PA-LIBs.Without external power source,the photo conversion efficiency of CuO based photocell reaches about 0.34%.Impressively,at a high current density of 4000 m A g^(-1),photoassisted discharge and charge specific capacity of CuO based PA-LIBs respectively receive 64.01%and 60.35%enhancement compared with the net electric charging and discharging process.Mechanism investigation reveals that photogenerated charges from CuO promote the interconversion between Cu^(2+)and Cu^(+)during the discharging/charging process,thus forcing the lithium storage reaction more completely and increasing the specific capacity of the PA-LIBs.This work can provide a general principle for the development of other high-efficient semiconductor-based PA-LIBs.

Two-dimensional MOF-based materials:Preparations and applications as electrodes in Li-ion batteries

Two-dimensional(2D)metal-organic frameworks(MOFs)are rapidly emerging as a unique class of mushrooming family of 2D materials offering distinctive features,such as hierarchical porosity,extensive surface area,easily available active sites,and versatile,adaptable structures.These promising characteristics have positioned them as highly appealing alternatives for a wide range of applications in energy storage technologies,including lithium batteries.Nevertheless,the poor conductivity and limited stability of 2D MOFs have limited their real applications in electrochemical energy storage.These limitations have therefore warranted ongoing research to enhance the performance of 2D MOFs.Given the significance of 2D MOF-based materials as an emerging class of advanced materials,a multitude of strategy has been devised to address these challenges such as synthesizing 2D conductive MOFs and derivatives along with 2D MOF hybridization.One promising approach involves the use of 2D MOF derivatives,including transition metal oxides,which due to their abundant unsatu rated active metal sites and shorter diffusion paths,offer superior electrochemical performance.Additionally,by combining pristine 2D MOFs with other materials,hybrid 2D MOF materials can be created.These hybrids,with their enhanced stability and conductivity,can be directly utilized as active materials in lithium batteries.In the present review,we categorize 2D MOF-based materials into three distinct groups:pristine 2D MOFs,2D MOFderived materials,and 2D MOF hybrid materials.The synthesis methods for each group,along with their specific applications as electrode materials in lithium-ion batteries,are discussed in detail.This comprehensive review provides insights into the potential of 2D MOFs while highlighting the opportunities and challenges that are present in this evolving field.

Two-dimensional MnN utilized as high-capacity anode for Li-ion batteries

When developing high performance lithium-ion batteries,high capacity is one of the key indicators.In the last decade,the progress of two-dimensional(2 D) materials has provided new opportunities for boosting the storage capacity.Here,based on first-principles calculation method,we predict that MnN monolayer,a recently proposed 2 D nodal-loop halfmetal containing the metallic element Mn,can be used as a super high-capacity lithium-ion batteries anode.Its theoretical capacity is above 1554 mA-h/g,more than four times that of graphite.Meanwhile,it also satisfies other requirements for a good anode material.Specifically,we demonstrate that MnN is mechanically,dynamically,and thermodynamically stable.The configurations before and after lithium adsorption exhibit good electrical conductivity.The study of Li diffusion on its surface reveals a very low diffusion barrier(~ 0.12 eV),indicating excellent rate performance.The calculated average open-circuit voltage of the corresponding half-cell at full charge is also very low(~0.22 V),which facilitates higher operating voltage.In addition,the lattice changes of the material during lithium intercalation are very small(~ 1.2%-~4.8%),which implies good cycling performance.These results suggest that 2 D MnN can be a very promising anode material for lithium-ion batteries.

An Air‑Rechargeable Zn Battery Enabled by Organic–Inorganic Hybrid Cathode

Self-charging power systems collecting energy harvesting technology and batteries are attracting extensive attention.To solve the disadvantages of the traditional integrated system,such as highly dependent on energy supply and complex structure,an airrechargeable Zn battery based on MoS_(2)/PANI cathode is reported.Benefited from the excellent conductivity desolvation shield of PANI,the MoS_(2)/PANI cathode exhibits ultra-high capacity(304.98 mAh g^(−1) in N_(2) and 351.25 mAh g^(−1) in air).In particular,this battery has the ability to collect,convert and store energy simultaneously by an airrechargeable process of the spontaneous redox reaction between the discharged cathode and O2 from air.The air-rechargeable Zn batteries display a high open-circuit voltage(1.15 V),an unforgettable discharge capacity(316.09 mAh g^(−1) and the air-rechargeable depth is 89.99%)and good air-recharging stability(291.22 mAh g^(−1) after 50 air recharging/galvanostatic current discharge cycle).Most importantly,both our quasi-solid zinc ion batteries and batteries modules have excellent performance and practicability.This work will provide a promising research direction for the material design and device assembly of the next-generation self-powered system.

基于调频信号自适应分解的电池储能辅助二次调频控制策略

以清洁能源发电为代表的零碳机组大规模并入电网,其间歇性和不确定性带来的频率波动愈发凸显。针对电池储能辅助火电机组调频灵活性不足、荷电状态维持效果不理想的问题,提出一种基于调频信号自适应分解的储能辅助二次调频控制策略。首先,综合灵敏度、储能荷电状态、频率偏差状态3个因素,给出区域调节需求信号和区域控制误差信号的切换时机判据;计及火电机组爬坡率限制和储能荷电状态限制,提出自适应调频信号分解策略,构建回报增益与荷电状态之间的规律并将其作为调节参考值,利用频率偏差对参考值进行修正,最后通过状态一致性检测模块判断回报增益的输出,以实现2种调频资源的优势互补。通过单区域系统频率响应模型仿真,验证了本文策略的有效性。结果表明:本文策略能够提高系统的灵活性,使各调频资源形成互补关系。

混合储能聚合商参与能量-调频市场控制策略

提出了一种混合储能聚合商(hybrid energy storage aggregator,HESA)参与能量-调频市场的控制策略。首先,对于独立系统运营商(ISO)发出的调频指令信号进行VMDWVD时频域分析,重构固有模态分量(IMF)生成高频信号与低频信号,分别作为HESA中功率型储能和能量型储能的输入信号。其次,构建了计及多市场价格不确定性的HESA投标与运行策略min-max-min模型,基于列和约束生成算法(C&CG)和强对偶理论对主子问题进行迭代交替求解。最后,基于实际PJM市场的价格、调频信号等数据进行了仿真,验证了HESA主体投标运营策略的有效性。

储能调频控制参数自适应优化与退出机制设计

为解决储能控制参数设置不当引起的频率稳定性问题以及储能调频效果和循环使用寿命难以平衡的问题,提出一种储能调频控制参数自适应优化与退出机制设计方法。首先分析储能下垂、虚拟正(负)惯量系数对系统频率动态性能及稳定性的影响,得到参数稳定变化的范围;然后,根据控制参数稳定变化区间,设计含虚拟负惯量的模糊自适应控制方法,实现控制方式之间的平滑切换和优势互补,加快频率恢复;再则,利用Logistic函数设计考虑储能荷电状态(SOC)的自适应反馈控制策略,同时引入储能退出机制,反馈调节优化储能出力,以期解决储能调频效果和循环使用寿命难以平衡的问题。最后,在Matlab/Simulink仿真平台上进行仿真验证,验证所提策略的有效性及对频率的改善作用。

典型调峰/调频工况下储能电池组荷电状态估计

针对储能电池组在电网典型储能工况下荷电状态(state of charge,SOC)估算精度较低的问题,提出一种基于核主成分分析(kernel principal component analysis,KPCA)-鹈鹕优化(pelican optimization algorithm,POA)-双向门控循环单元(bidirectional gated recurrent unit,Bi GRU)的SOC估计模型。通过设计调峰/调频工况下电池组充放电实验,从数据中提取表征SOC变化的融合特征作为模型输入;分别构建不同工况下Bi GRU网络,并利用POA对其超参数进行优化,提高模型性能;进一步在混合工况下验证模型的有效性。结果表明,所建模型有着更好的SOC估计效果和更强的鲁棒性,能够提高复杂储能工况下储能电池组SOC估计精度。

电网储能用磷酸铁锂电池弛豫现象研究

磷酸铁锂储能电池长时间处于调峰调频复杂工况下会引起电池电极活性降低和寿命衰减现象。开展了调峰调频工况下磷酸铁锂储能电池模组的充放电实验,对其弛豫行为进行分析,对比不同荷电状态(SOC)、不同充放电方式、不同充放电倍率下弛豫电压的变化,提出电压偏移率作为度量电压恢复能力的指标。实验结果表明:调频模式的电压恢复时间大于调峰模式,电流倍率越大,弛豫时间越长;调峰模式下每次充放电循环后间歇静置540~660 s,调频模式下每次循环后静置900~1100 s,有利于电压的恢复。

功率型储能技术在新能源场站一次调频中的作用及应用研究

在以新能源为主体的新型电力系统中,面临着由新能源发电量大比例增加导致电力系统安全稳定运行风险增大的问题,主要表现为电网调节能力及抗干扰能力不断下降。如何通过先进的储能技术解决新能源场站调频能力不足的问题,研制适用于新能源场站一次调频支撑的功率型储能系统,为电网支撑型新能源场站进行技术储备和规模化实证,从而实现大规模新能源电力的友好高效送出。从新能源场站实际工程应用的角度出发,提出采用钛酸锂电池、飞轮储能和超级电容这3种不同的新型功率型储能技术构成的一次调频储能系统,对功率型储能技术在新能源场站一次调频中的作用和功能进行了验证。研究结果表明:实现一次调频功能是新能源场站从非主体电源成长为主体电源过程中应当承担的责任,对电力系统的安全稳定将起到积极的支撑作用;采用灵活的站控层结构和快速的通信方式,才能充分发挥一次调频储能系统的快速响应特性;功率型储能技术的充放电循环寿命长,更适用于一次调频的应用场景。研究结果可促进功率型储能产业链的加速完善。

调峰/调频模式下储能电池热仿真与实验

为探究储能电池参与电网调峰/调频时的运行状态,根据江苏镇江储能电站的实际运行工况,通过有限元仿真的方法建立了磷酸铁锂储能电池模组热模型。进一步设计了电池调峰/调频循环老化实验,分析早期容量衰减和温度变化数据,验证仿真的温度分布,并得出调峰/调频模式下的运行规律。结果表明:调峰模式平均电流倍率大,电池温度维持在更高的区间,最大温差远高于调频,在同等放电容量下电池寿命衰减更明显;仿真能较好地反映模组内部均温变化趋势,误差均低于1.8℃,满足预测精度,可为储能电站的初期投运提供安全设计基础。

水储联合调频系统模型及控制策略研究

对电池储能调频可行性进行了分析研究,构建了储能-水电多目标优化数学模型,提出了储能参与水电机组二次调频的多目标优化策略,经过仿真分析验证电池储能参与水电调频能够满足控制要求,给出了水储联合调频系统部署方式、运行方式、储能配置方案及预算,为大型水电站开展水储联合调频运行提供了理论技术支持,对同类型水储联合调频项目建设具有一定的借鉴作用。

Experimental Study on the Effect of State of Charge on Failure Propagation Characteristics within Battery Modules

To investigate the effect of different states of charge(SOC)on the thermal runaway(TR)propagation behaviors within lithium-ion-batteries based energy storage modules,an experimental setup was developed to conduct failure propagation tests on battery modules at an SOC of 97%,85%,and 50%.The result indicates that an increase in the SOC of batteries can decrease the TR trigger temperature,making batteries trigger TR earlier and reducing the average failure propagation time between two adjacent cells.In addition,the failure propagation tests reveal that at higher SOCs,the TR reaction becomes more violent,the maximal reaction temperature is also much higher,and the damage to the battery module is severe.Compared to the battery module with 97%SOC,the TR trigger time of the battery module with 50%SOC was postponed by approximately 57.8%.Meanwhile,the average failure propagation time got prolonged by approximately 36.0%.Thus,this study can provide references for the thermal safety design of energy-storage battery modules.

Recent advances of magnesium hydride as an energy storage material

Energy storage is the key for large-scale application of renewable energy,however,massive efficient en-ergy storage is very challenging.Magnesium hydride(MgH_(2))offers a wide range of potential applications as an energy carrier due to its advantages of low cost,abundant supplies,and high energy storage capac-ity.However,the practical application of MgH_(2) for energy storage is still impeded by its sluggish kinetics,poor cycling stability,etc.Herein,we provide an overview of recent advances of MgH_(2) for enhancing the hydrogen storage,lithium-ion storage,and heat storage performances.For hydrogen storage,a particular emphasis was put on altering the kinetics and thermodynamics of MgH_(2) via catalyzing,alloying,nano-sizing,and compositing.Modifications to MgH_(2) as a battery anode material mainly focus on the effect of additives,electrolytes,and structure configurations.Prototype heat storage apparatus was proposed based on MgH_(2) and coupled with other materials or systems to improve the heat storage and economic efficiency.Besides,prospects of MgH_(2) in these fields are discussed.This review would stimulate more insightful and pioneering research for the design and preparation of MgH_(2) with excellent energy storage performances.

高效供电系统可靠性与安全性分析

高效供电系统主要用于满足严苛环境下的工作特性和稳定性要求,但由于锂离子电池内部是非稳态的电化学体系,因热滥用、电滥用和机械滥用等异常情况发生可能会产生安全隐患,从而造成严重经济损失和恶劣社会影响。文章提出一种分析验证该系统可靠性与安全性的方法,通过建模分析、热设计仿真验证其可靠性;且经热设计仿真分析满足在高温下长循环情况下的温度稳定性,但水冷板仍有优化空间;采用硬件分析法,分析该系统锂离子电池储能模块在使用过程中可能或实际发生的故障模式,为提高系统使用可靠性、运行安全性等提供依据。

大容量储能电池模组热失控传播行为与燃爆风险分析

锂离子电池热失控引发的储能系统火灾爆炸问题长期制约着产业发展。为了探究实际应用场景下大容量储能电池、电池模组的热失控及其传播行为与燃爆风险,本文以储能用280 Ah磷酸铁锂电池及其组成的1P48S电池模组为研究对象,对热滥用条件下电池单体产热、产气特征以及真实模组内热失控蔓延特征进行了实验研究,并基于试验产气结果,对2种典型储能应用场景下因模组热失控传播而导致的燃爆风险进行了分析,结果表明:电池单体热失控产生最高温度为380.1℃,热失控释放混合气体总量为156.8 L,混合气体爆炸极限为6.9%~35.5%;模组内设置的隔热板有效阻隔了热失控蔓延,其间未设隔热板的6块电池发生了热失控,热失控电池表面最高温度超1200℃,热失控传播速度为0.162~0.233 mm/s,同时在热失控高温影响下模组箱体外部上表面温度最高达281.3℃;模组内6块电池热失控会导致预制舱式储能系统较高燃爆风险,应将热失控传播控制在2块电池以内,但模组内1块电池从开阀产气至热失控的过程中便会导致工商业用储能柜较高的燃爆风险。该研究可为储能电池模组安全设计和储能系统防爆设计提供参考。

考虑荷电状态的电池储能一次调频综合控制方法

为提高储能电池参与电网一次调频的性能,提出一种兼顾电网频率稳定性和储能电池荷电状态的综合控制策略。通过设定合适的出力系数,将虚拟惯性控制策略和虚拟下垂控制策略相结合,根据储能电池荷电状态的不同,控制储能电池总的出力大小,根据频率偏差的大小,控制虚拟下垂出力和虚拟惯性出力的占比,设置较优的储能频率死区范围,提高机组的经济性。仿真结果表明,综合控制策略在系统受到阶跃负荷扰动时,相较于其他控制方法,消耗的储能电池电量至少降低了1.86%,有效地提高电池荷电状态的维持效果;在系统受到连续负荷扰动时,最大频率峰谷差至少降低了13.4%,在连续仿真300 s后,电池荷电状态也最接近设定值。表明所提出的综合控制策略能够有效提高电力系统的一次调频效果,并保持电池的荷电状态处于合理范围。

基于区域直线距离的锂离子电池健康状态评估

在原始充电曲线中引入区域电压和区域直线距离的概念,并提出基于区域直线距离的电池S_(OH)(健康状态)评估方法,采用实验室条件下NCA(镍钴铝)电池单体和LFP(磷酸铁锂)电池模组在1/2C倍率下的充电电压数据以及一座20 kW/100 kW·h储能电站的电池运行数据,来建立基于区域直线距离的电池S_(OH)评估模型,对比了基于区域直线距离L_(AB)的方法和IC(增量容量)峰高法,并考察了不同采样频率和区域电压下L_(AB)-S_(OH)模型的效果。结果表明:S_(OH)与L_(AB)呈线性正相关,线性拟合优度可达到0.96以上,L_(AB)-S_(OH)模型的S_(OH)评估准确性均优于IC峰高法。区域直线距离作为健康因子提高了低采样频率下电池S_(OH)评估的准确性,这为工程上储能电池的S_(OH)在线评估提供了可能性。

锂电池和超级电容混合储能系统在燃煤电厂的应用与研究

燃煤机组通过采用锂电池和超级电容混合储能系统,可以迅速响应辅助调频市场需求,有效延长锂电池寿命,增加调频收益。从南方某电厂实际投产的混合储能系统的系统结构、运行方式、控制策略、经济效益等多角度出发,介绍了锂电池和超级电容混合储能系统在燃煤机组中的结构特点和实际商业运行情况,为火电厂混合储能系统发展提供了有价值的参考。

基于储能电池的H桥功率模块对拖试验研究

主要研究基于储能电池的H桥功率模块对拖试验相关内容。首先,介绍了主回路和控制回路拓扑设计,每个H桥功率模块直流侧均并联一个储能电池。其次,提出了整个试验系统的保护协调配合与动作原则,主控制器负责总体保护及保护的协调配合,功率模块、水冷系统、BMS负责各自保护。最后,提出有功无功对拖控制策略以及具体试验流程,实现两个功率模块的有功和无功满功率试验。