共查询到20条相似文献,搜索用时 46 毫秒
1.
2.
以某款52 Ah储能用方形磷酸铁锂电池单体为对象,采用400 W的外部热源、20.8~166.4 W(1~8 h)的恒功率放电以匹配电池工作状态下的热滥用条件,测量电池热失控过程中的表面温度和电压,记录热失控实验现象和关键时间点,对比研究不同放电功率对热滥用诱发热失控进程的影响。结果表明,放电操作会加速热失控的进程,且放电功率越大,热失控越早发生,从不放电到166.4 W恒功率放电,安全阀打开时间缩短了23.4%,热失控触发时间缩短了5.6%;与此同时,四组放电工况由于放出部分能量,最终热失控的严重程度有所降低,放电工况下的热失控最高温度和最大温升速率比不放电工况最高分别下降了9.0%和53.3%;另外,放电操作会造成热失控过程中电压更大的波动,后续电压下降的时间窗口前移至开阀时间附近,这将更有利于利用电压变化对热失控进行预警。总体而言,放电操作在加速热失控进程的同时,降低了热失控最终的严重程度。本工作可对电化学储能电站的日常安全运营和电池管理系统设计提供参考。 相似文献
4.
5.
6.
7.
磷酸铁锂电池以其较好的安全性在储能领域得到了广泛应用。本工作以额定容量21 Ah的软包磷酸铁锂电池为实验对象,在25℃下以4.05 V、4.25 V、4.50 V和5.0 V高电压下浮充电24 h。研究单体高温热失控和材料热稳定性。结果表明,在4.25 V、4.50 V和5.0 V电压下均出现鼓胀,电压升高鼓胀加剧。在5.0 V电池破裂,负极活性材料溶解,铜集流体裸露,同时出现大量锂沉积。在4.05 V、4.25 V和4.50 V下浮充后的高温热失控试验中发现,随电压升高电池破裂温度下降,热失控触发温度由249.86℃升至278.65℃,提前破裂释放能量使得热失控触发温度升高,但并不具有较好的安全性,热失控最高温度由484.67℃升至516.08℃,最大温升速率也明显升高,且热失控触发到最高温度时间缩短,高电压浮充后电池热稳定性变差,热失控更加剧烈。隔膜在120.63℃开始发生相变,在367.06℃开始分解。而正、负极未出现明显分解,其自身热稳定性较好。因此应避免高电压使用,保持电池安全使用和稳定运行。 相似文献
8.
随着电化学储能应用规模的持续扩大,使用锂离子电池的电化学储能电站火灾燃爆事故时有发生,引发社会的广泛关注。锂离子电池的安全性是影响储能电站安全的重要因素,分析储能用锂离子电池的热失控行为及燃爆特性是有效防控储能电站火灾事故的关键。本工作选用储能用280 Ah磷酸铁锂电池为研究对象,基于锂离子电池热失控及产气分析测试平台,采用加热方式触发电池热失控,分析其产热、质量损失以及产气特性。进一步采用傅里叶变换红外光谱仪以及氢气传感器测量热失控过程产气成分,通过卷积分析得到气体组分占比,其中氢气和二氧化碳分别占36.8%和44.2%。通过FLACS软件建立电池储能液冷舱1∶1模型,分析了不同条件下磷酸铁锂电池产气发生燃爆的动压及火焰危害范围。研究发现,在电池储能舱内发生的燃爆行为受到舱室内部泄压开启压力和周边障碍物的影响,而其中当舱门开启压力从10 kPa增长到100 kPa时,爆炸超压峰值增长为2.15倍。该研究可为储能电站锂离子电池火灾事故预警、集装箱结构和防爆设计提供参考。 相似文献
9.
10.
采用化学氧化还原法制备的石墨烯和化学气相沉积法制备的三维网状石墨烯共同作为导热填料改性环氧树脂,研究导热填料质量分数的变化对环氧树脂热导率的影响,并进一步测定复合热界面材料的热导率在高温下的稳定性。结果表明:当石墨烯-三维网状石墨烯的质量分数为0.2(石墨烯和三维网状石墨烯的比例为1∶9)时,可使环氧树脂的热导率提高2 400%;三维网状石墨烯的三维网状结构和石墨烯的表面官能团对复合热界面材料的热性能具有显著地影响;三维网状石墨烯为声子提供了快速传输通道,而石墨烯的表面官能团能促进环氧树脂与石墨烯之间形成良好的接触,降低界面热阻,在石墨烯和三维网状石墨烯的协同作用下可提高热界面材料的热导率。此外,可以通过优化导热填料的尺寸,提高复合热界面材料热导率的稳定性。 相似文献
11.
《Journal of power sources》2002,104(1):108-114
Electrochemical properties of plasma-fluorinated graphite samples have been investigated in 1 mol dm−3 LiClO4 ethylene carbonate (EC)/diethyl carbonate (DEC) solution at 25 °C. Fluorine contents in plasma-fluorinated graphite samples were in the range of 0–0.3 at.% by elemental analysis and surface fluorine concentrations obtained by X-ray photoelectron spectroscopy (XPS) were in the range of 3–12 at.%. Raman spectroscopy revealed that surface disordering of graphite was induced by plasma fluorination. Plasma treatment increased the surface areas of graphite samples by 26–55% and the pore volumes for the mesopores with diameters of 1.5–2 and 2–3 nm. Plasma-fluorinated graphites showed capacities higher than those of original graphites and even higher than the theoretical capacity of graphite, 372 mAh g−1, without any change of the profile of charge–discharge potential curves. The increments in the capacities were approximately 5, 10 and 15% for graphites with average particle diameters, 7, 25 and 40 μm, respectively. Furthermore, the coulombic efficiencies in first cycle were nearly the same as those for original graphites or higher by several percents. 相似文献
12.
锂电池是理论能量密度最高的化学储能体系,估算各类锂电池电芯和单体能达到的能量密度,对于确定锂电池的发展方向和研发目标具有重要的参考价值。本工作根据主要正负极材料的比容量、电压,同时考虑非活性物质集流体、导电添加剂、黏结剂、隔膜、电解液、封装材料占比,计算了不同材料体系组成的锂离子电池和采用金属锂负极、嵌入类化合物正极的金属锂离子电池电芯的预期能量密度,并计算了18650型小型圆柱电池单体的能量密度,为电池发展路线的选择和能量密度所能达到的数值提供参考依据。同时指出,电池能量密度只是电池应用考虑的一个重要指标,面向实际应用,需要兼顾其它技术指标的实现。 相似文献
13.
We show that anodes made by depositing thin films of polymer-derived silicon oxycarbide (SiCO) on copper have properties that are comparable to, or better than that of powder-based SiCO anodes. The great advantage of the thin film architecture is its simplicity, both in manufacturing and in application. The films are produced by spraying a film of the liquid polymer-precursor on copper, and then converting it into SiCO by heating at ∼1000 °C; at this point they are ready for constructing electrochemical cells. They show a capacity of ∼1000 mA h g−1, 100% coulombic efficiency, good capacity at very high C-rates, and minimal fading at ∼60 cycles. However, if the films are thick they delaminate due to the volume change as lithium is cycled in and out. The transition from thin-film to thick-film behavior occurs when the SiCO films are approximately 1 μm thick. An analytical method for estimating this transition is presented. 相似文献
14.
《Journal of power sources》2006,158(1):557-563
Composites comprising silicon (Si), graphite (C) and polyacrylonitrile-based disordered carbon (PAN-C), denoted as Si/C/PAN-C, have been synthesized by thermal treatment of mechanically milled silicon, graphite, and polyacrylonitrile (PAN) powder of nominal composition C–17.5 wt.% Si–30 wt.% PAN. PAN acts as a diffusion barrier to the interfacial diffusion reaction between graphite and Si to form the electrochemically inactive SiC during prolonged milling of graphite and Si, which could be easily formed in the absence of PAN. In addition, graphite, which contributes to the overall capacity of the composite and suppresses the irreversible loss, retains its graphitic structure during prolonged milling in the presence of PAN. The resultant Si/C/PAN-C based composites exhibit a reversible capacity of ∼660 mAh g−1 with an excellent capacity retention displaying almost no fade in capacity when cycled at a rate of ∼C/4. Scanning electron microscopy (SEM) analysis indicates that the structural integrity and microstructural stability of the composite during the alloying/dealloying process appear to be the main reasons contributing to the good cyclability observed in the above composites. 相似文献
15.
AbstractLi2MnO3 based layered Li-rich materials as promising cathode candidates of Li ion batteries (LIBs) have attracted much recent attention mainly owing to their superior high specific capacity and high working voltage. To date, although researchers have put much effort to this family of materials, there are still a number of issues under debates in the fundamental understanding of the crystal structures and the electrochemical reaction mechanisms, before the materials can be ready for practical applications. In this review article, we address the recent progress of this group of Li-rich cathode materials with a good hope to better understanding of the relationships among composition, crystal structure and electrochemical reaction mechanisms. In addition, the use of advanced microscopic characterisation and the strategies of novel material designs will also be discussed for better cathode design for LIBs. 相似文献
16.
锂离子电池因其高能量密度和长循环寿命而得到广泛应用.然而当多个电池通过串联或者并联成组时,电池组往往存在容量衰减过快,寿命较短的问题,这是由于电池单体之间的非一致性而造成的.如何利用简单,可靠的分选方法,筛选出性能尽可能一致的电池用来成组,对锂离子电池在大规模储能中的推广应用具有重要的科学与实践意义.该文综述了目前国内外锂离子电池一致性的分选方法,包括各方法的机理特点,并且简单介绍了作者课题组在这方面的研究进展.采用阻抗谱方法或许是建立准确,快速的评价体系和提高配对电池的一致性的有效分选方法. 相似文献
17.
Thermal runaway fire characteristics of lithium ion batteries with high specific energy NCM811 下载免费PDF全文
DONG Haibin ZHANG Shaoyu LI Yi XIAN Xuelei YI Chengyi LIU Lianxi YU Dongxing HAN Guang SHENG Yanfeng 《储能科学与技术》2019,8(Z1):65-70
通过NCM811高比能锂离子电池在低氧环境、电滥用、热滥用和机械滥用工况下热失控实验研究,获取该电池的热失控特性及关键参数,为进一步的热失控早期预警和火灾扑救研究提供了技术支持。 相似文献
18.
Hadi Bashirpour-Bonab 《国际能源研究杂志》2020,44(15):12583-12591
Electric vehicles equipped with lithium-ion batteries face a huge challenge, and the fact that battery life is very much affected by the temperature conditions of their operating environment, the heat reduces battery life cycle and time and increases the likelihood of thermal degradation and explosion. This problem has forced engineers to cool the battery. The methods used to cool the battery includes a cool water method (passing water or a dielectric fluid from the battery pack), cooling air (blowing air into the battery compartment by the fan), using a refrigeration system (such as cooling screens), and the use of phase-change material (PCM). In this research after reviewing and referring to valid authorities, it was found that PCMs are superior to all three other cooling systems because the air-conditioning system is not very desirable due to the high-temperature gradient between the battery cells. Also, cooling and refrigeration systems with refrigerant gases will also cost a very high cost on the electric car. The results of the studies showed that the cooling the battery using the PCM creates a similar temperature profile between the batteries in the battery pack, the temperature gradient is much smaller than the air cooler and cool water, and the final cost will be much lower. Also, it performs more efficiently in high-speed road dynamics and increases the battery life of an electric car or electric hybrid. 相似文献
19.
Composite electrodes of reassembled titanate and two kinds of carbon fibers were prepared and their high-rate electrode properties were examined. Multi-walled carbon nanotubes (MWNT) and vapor-grown carbon fibers (VGCF) were used for preparing the composites. The electronic conductivity of the MWNT composites increased with increasing contents of MWNT and exhibited a typical insulator-conductor transition. The MWNT composite with a MWNT content of 50 wt.% showed a capacity of 150 ± 5 mAh (g titanate)−1 at a discharge rate of 0.67 C, and did not show a good high-rate capability due to the large content of hydrated water. The effect of the porous structure of the electrodes was revealed in the high-rate electrode properties of the microstructurally controlled composites with both MWNT and VGCF. The composites with 50 wt.% VGCF and 10 wt.% MWNT showed a reversible capacity of approximately 160 mAh (g titanate)−1 at a discharge rate of 0.63 C and almost no capacity fading at relatively large discharge rate up to 19 C. A composite electrode with excellent high-rate capability was obtained by the microstructural control with carbon fibers. 相似文献
20.
Several substituted titanates of formula Li4−xMgxTi5−xVxO12 (0 ≤ x ≤ 1) were synthesized (and investigated) as anode materials in rechargeable lithium batteries. Five samples labeled as S1–S5 were calcined (fired) at 900 °C for 10 h in air, and slowly cooled to room temperature in a tube furnace. The structural properties of the synthesized products have been investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier transmission infrared (FTIR). XRD explained that the crystal structures of all samples were monoclinic while S1 and S3 were hexagonal. The morphology of the crystal of S1 was spherical while the other samples were prismatic in shape. SEM investigations explained that S4 had larger grain size diameter of 15–16 μm in comparison with the other samples. S4 sample had the highest conductivity 2.452 × 10−4 S cm−1. At a voltage plateau located at about 1.55 V (vs. Li +), S4 cell exhibited an initial specific discharge capacity of 198 mAh g−1. The results of cyclic voltammetry for Li4−xMgxTi5−xVxO12 showed that the electrochemical reaction was based on Ti4+/Ti3+ redox couple at potential range from 1.5 to 1.7 V. There is a pair of reversible redox peaks corresponding to the process of Li+ intercalation and de-intercalation in the Li–Ti–O oxides. 相似文献