不同放电倍率磷酸铁锂电池循环性能研究

磷酸铁锂电池的容量、能量、内阻和开路电压是其性能的重要指标,也是涉及电池管理系统设计的重要参数.这些特性均与电池充放电倍率紧密相关.通过对40 ℃下不同放电倍率的LiFePO₄锂离子电池的容量、能量、交流阻抗和开路电压等循环性能试验,研究不同放电倍率循环下以上特性的变化规律.结果表明,电池放电容量与放电倍率间满足幂函数规律; 高倍率下循环,电池容量衰减更快; 在循环过程中,放电倍率对电池的欧姆阻抗和电化学阻抗的影响程度不同,欧姆内阻受倍率影响很小,电化学阻抗则随着放电倍率升高,增加越快; 另外,在循环后期,放电倍率越高,开路电压下降越快; 大电流下,电池放出能量降低,产热增加,老化加快,寿命降低.      

基于高镍三元材料锂离子动力电池在循环前后的热特性分析

为明确循环后高比能Li[Ni_(0.7)Co_(0.15)Mn_(0.15)]O_2/graphite锂离子动力电池的温度特性及产热机制。研究了循环前后电池的倍率放电性能和温度特性,并对比分析了循环前后影响电池产热的关键因素,即可逆反应热(熵热系数)和不可逆阻抗热(过电压)的变化。结果表明:与循环前电池的放电性能相比,循环后的电池放电容量和放电电压下降,放电初期电压下降显著,倍率放电性能变差;放电过程中温度的增加明显高于循环前电池,且温度的升高主要是放电初始阶段温度的升高;对比循环前后电池表面温度分布发现,放电初期循环前电池表面温度正极较高,循环后电池表面温度负极较高,放电结束时均为中心区域温度最高;电池的温度变化源于电池的可逆反应热和不可逆阻抗热,循环前后电池的可逆反应热变化不大,循环后电池在放电过程中温度显著增加的主要原因是由于放电初始阶段不可逆阻抗热的显著增大所造成的。     

微热管阵列应用于锂电池模块的散热实验

锂离子电池在大功率应用下的热控制和热管理已成为制约电动汽车商业化的瓶颈,为解决此问题,运用微热管阵列设计锂电池模块散热系统,在开放条件下对电池模块进行恒流18 A（1 C）和36 A（2 C）充放电测试,通过测量布置微热管阵列前后电池表面温度可知:在1 C和2 C充放电倍率下,散热系统能够有效的降低电池模块的温度及电池间温度差异,将温度和温度差值分别控制在40℃与5℃之内,可以解决温度对电池寿命和容量的影响问题.基于实验数据,对其中一2 C工况热量进行了计算,得到通过微热管阵列的对流散热量达到模块生热量的40%.      

电动车用高功率型动力镍氢电池的性能研究和测试分析

研究了电动车用高功痃型Ni－MH电池的比功率、高温充放电效率、荷电保持能力、大电流放电能力和循环寿命等性能,高功率电池的大电流放电能力可大于12.5C左右。     

锂离子电芯用电极对温度与SOC的敏感性

采用阻抗谱技术,对2.8 A·h 18650电芯进行拆解解析,单独分析正负极电极在不同温度下(25、10和-5℃),不同荷电状态下的阻抗变化.结果表明:在不同温度下,在20%~100%荷电状态下,负极作为控制电极,其反应电化学阻抗是正极的数倍,尤其是在-5℃,达到了4倍,负极是电芯一致性问题中动力学因素的控制主因;在0~20%荷电状态下,在10和25℃下,正极的反应电化学阻抗要远远大于负极,正极成为控制端.结合目前电动车上动力电池的实用荷电状态一般在20%~95%,针对该2.8 A·h 18650电芯,提高负极电极的一致性是核心所在.同理,对其他类型电芯而言,在电芯设计过程中,在综合考虑成本的前提下,需要更有针对性地提高正负极的一致性标准,从而更为有效地改善整个电芯产品的一致性.      

锂离子电池新型正极材料LiFePO4／C的合成

采用高温固相合成法合成了锂离子电池正极材料LiFePO4/C,并对其晶体结构、形貌和电化学性能进行了研究.结果表明:合成的LiFePO4/C材料为单一橄榄石型结构,颗粒分布比较均匀;以0.1 C倍率充放电时其初始比容量为115 mA·h/g,20次循环后其容量保持率为97%.     

电动车电池延长使用寿命的诀窍

对车的处理 首先,整车行驶时的电流对电池寿命至关重要.如电摩的电池,放电电流经常接近1C,甚至超过1C,这样的电池寿命难以达到很长.     

快速充电的奇妙作用

着重介绍了快速充电对电动车用阀控铅酸蔷电池有修复性的提升容量和延长寿命的奇妙作用,希单引起重视,加强推广和应用.同时说明了对充电快慢的分类和定义.     

柠檬酸络合法合成的尖晶石LiMn2O4特性研究

锂离子电池具有比能量高、质量轻、体积小、电压高、安全性好和无记忆效应等特点,而正极材料是其研究的重点.采用柠檬酸络合法成功地合成了锂离子电池正极材料LiMn2O4,并用X射线衍射仪、红外光谱、差热分析仪和扫描电镜等手段对其最优合成条件及合成产物的结构和电化学性能作了初步研究.在最佳条件下,即柠檬酸与金属离子的摩尔比为1.3左右及温度为700℃,制备的正极材料LiMn2O4具有较高的初始容量和较好的循环稳定性,即初始放电容量约为132 mAh·g-1,40次循环后能保持初始容量的90%,完全可以用于高比能长寿命的锂离子蓄电池.     

烧结温度对LiNi0.8Co0.15Al0.05O2结构和电化学性能的影响

采用共沉淀法+高温固相法,首次在740~820℃制备了一系列LiNi_0.8Co_0.15Al_0.05O₂正极材料,探讨温度变化对材料结构性能的影响.通过X射线分析仪、扫描电镜、电化学工作站、电池充放电测试系统表征材料性能.结果显示在780℃烧结出的材料有纯的六方晶相、层状结构优异,在2.75~4.2 V、0.1 C倍率获得188.11 mAh/g,0.5 C循环100次后容量稳定率为88.55 %,高于其他温度制备的材料; 经过不同倍率放电后,780℃烧结出的材料不可逆容量损失远低于其他温度制备的材料.      

低阻高性能阳极钢爪材料开发设计及工业试验

阳极钢爪是电解铝阳极导杆与炭块间的连接结构,需要在电解环境下给电解槽传输强大的直流电流并夹持阳极碳块,因此需要其具有较高的高温强度、高温导电性以及较低的成本。当前阳极钢爪材料缺乏行业规范,生产原料、生产方式等控制不严格,使得钢爪存在电阻大、压降高、强度低等问题。针对这些问题开发了低阻高性能高强度阳极钢爪材料,并在某300 kA系列试验槽进行了工业试验。工业试验结果表明,低阻高性能阳极钢爪压降33.9 mV,较现用新钢爪降低42.7 mV,降电压效果显著,为电解槽进一步节能降耗提供了空间。     

铝电解槽节能潜力分析与应用实践

铝电解槽的电能消耗量与平均电压和电流效率两个因素有关,降低槽电压或者提高电流效率,可降低铝电解槽直流电耗。通过系统测试系列电解槽电压平衡、能量平衡、电流效率,深入挖掘分析,提出了节能降耗技术措施。通过2台试验槽工业试验表明,试验槽平均电压3.819 V,电流效率92.89%,吨铝直流电耗12 251 kWh。与系列电解槽相比,平均电压降低99 mV,电流效率提高1个百分点,吨铝直流电耗降低455 kWh,节能效果显著。     

Slowly inactivating sodium currents are reduced by exposure to oxidative stress

Exposure of cardiac myocytes to oxidant stress has been implicated in the development of reperfusion arrhythmias. Studies on the effects of free radical generating systems on the fast sodium current have suggested an increase in a "window" current. The resulting increase in sodium influx has been hypothesized to cause an intracellular sodium load that stimulates Na+, Ca2+ exchange and promotes a Ca2+ overload. To test this proposal, the time course for effects of oxidative stress on a sodium current elicited with voltage ramps was investigated in feline ventricular myocytes. No window current was observed; instead, a slowly inactivating sodium current was generated at negative voltages near the sodium threshold potential. At room temperature there were no effects of a 30-min exposure to 1 mm H2O2 on this slowly inactivating sodium current. Likewise, there were no effects of either 1 mm H2O2 or 1.5 mm t-butyl hydroperoxide on fast sodium currents recorded at cool temperatures (12-15 degrees C). Experiments were repeated with t-butyl hydroperoxide at warm temperatures (30-33 degrees C), and the fast sodium current was reduced in magnitude and the reversal potential shifted to more negative voltages. These results demonstrate a temperature dependence for the loss of the fast sodium current during exposure to t-butyl hydroperoxide. Two exponentials were fit to the decaying phase of the fast sodium current and the slow time constant of inactivation was prolonged, suggesting delayed inactivation of the sodium current. Currents elicited with a steady-state inactivation protocol suggested development of a non-inactivating component during exposure to t-butyl hydroperoxide at warm temperatures. Direct evaluation of the slowly inactivating sodium current elicited by voltage ramps at warm temperatures (33-35 degrees C), and analysed as subtraction currents to remove background leak currents, showed a gradual reduction. It is concluded that the non-inactivating component identified during analysis of the fast sodium current was not the result of enhancement of either a slowly inactivating sodium current or a window current. Thus, an increase in sodium influx through voltage-dependent sodium channels does not occur during exposure to oxidative stress, and therefore, cannot induce an intracellular sodium load.     

Cu（Ⅱ）-Ethylenediamine-NH4Cl-NH3-H2O体系稀溶液铜电积新工艺研究

本文重点用控制变量的方法研究了在氨体系中温度、电流密度、铜离子浓度、pH等对电积过程中电流效率与槽电压的影响,总结了在稀溶液铜（Ⅱ）-氯化铵-氨-水体系中铜电积的一些规律。     

Audiometric bone conduction

Audiometric bone conduction test data are obtained with a unit that permits comparison with a recognized standard because the unit can be calibrated to operate within specified limits. Proper calibration of the unit is necessary if the equipment is to be accurate. Two procedures can be helpful in determining the need for calibration: the average loss method and the input voltage measurement method. Neither should supplant calibration, but each offers a means of checking the output of the unit. Confidence in auditory test data is increased when there is a high degree of consistency among the various tests; the availability of several different tests in the audiometric series can be used to an advantage then in a determination of consistency. An additional opportunity to ascertain the existence of consistency is present when tuning fork tests are employed as part of the total evaluation. The use of a masking stimulus in the nontest ear simultaneously with the presentation of the test tone to the test ear can be extremely useful in defining the type as well as the extent of the hearing loss. Presentation of the test tone and the masking stimulus in controlled discrete steps is the key to the interpretation of masking results.     

Temperature dependence of voltage-gated H+ currents in human neutrophils, rat alveolar epithelial cells, and mammalian phagocytes

H+ currents in human neutrophils, rat alveolar epithelial cells, and several mammalian phagocyte cell lines were studied using whole-cell and excised-patch tight-seal voltage clamp techniques at temperatures between 6 and 42 degrees C. Effects of temperature on gating kinetics were distinguished from effects on the H+ current amplitude. The activation and deactivation of H+ currents were both highly temperature sensitive, with a Q10 of 6-9 (activation energy, Ea, approximately 30-38 kcal/mol), greater than for most other ion channels. The similarity of Ea for channel opening and closing suggests that the same step may be rate determining. In addition, when the turn-on of H+ currents with depolarization was fitted by a delay and single exponential, both the delay and the time constant (tauact) had similarly high Q10. These results could be explained if H+ channels were composed of several subunits, each of which undergoes a single rate-determining gating transition. H+ current gating in all mammalian cells studied had similarly strong temperature dependences. The H+ conductance increased markedly with temperature, with Q10 >/= 2 in whole-cell experiments. In excised patches where depletion would affect the measurement less, the Q10 was 2.8 at >20 degrees C and 5.3 at <20 degrees C. This temperature sensitivity is much greater than for most other ion channels and for H+ conduction in aqueous solution, but is in the range reported for H+ transport mechanisms other than channels; e.g., carriers and pumps. Evidently, under the conditions employed, the rate-determining step in H+ permeation occurs not in the diffusional approach but during permeation through the channel itself. The large Ea of permeation intrinsically limits the conductance of this channel, and appears inconsistent with the channel being a water-filled pore. At physiological temperature, H+ channels provide mammalian cells with an enormous capacity for proton extrusion.     

Migration testing with olive oil in a microwave oven

A study was carried out to compare the overall migration from packaging materials into olive oil during heating in a microwave oven, and the overall migration from the same materials into olive oil but applying time and temperature conditions stipulated in the current EC and Dutch legislation on food packaging. Application of additional test conditions (e.g. 30 min and 1 h in combination with test temperatures exceeding 121 degrees C, and a test temperature of 130 degrees C) have demonstrated the need for extension of the test conditions mentioned in existing food packaging regulations to enable realistic migration testing of microwave packaging materials under conventional test conditions. It is concluded that the overall migration into olive oil from packaging materials intended for microwave oven use, including susceptor materials, can be judged on the basis of migration testing using conventional heating. For testing film or susceptor materials in a microwave oven by one-sided contact, a migration cell transparent to microwaves was developed and used up to 200 degrees C. In conventional high-temperature tests applying hot-filling of trays or migration cells, a temperature drop was observed, while handling oil at temperatures of 150 degrees-175 degrees C may be considered perilous. To prevent problems of this kind it is proposed to start migration tests at room temperature and to heat the simulant rapidly to the final test temperature. This procedure is comparable to migration tests carried out with aqueous food simulants at 121 degrees C in an autoclave.(ABSTRACT TRUNCATED AT 250 WORDS)     

电解铝预焙槽二次启动延长槽寿命的探讨

针对小修槽自身的特点,并借鉴以往大修槽的启动经验,对预焙槽二次启动延长槽寿命的工艺进行了探讨。认为:炉膛修补是保证电解槽寿命的先决条件;焙烧时的温度控制需讲究平稳均匀的原则,而采用纯石墨焙烧以及利用软连接分流技术可以使焙烧温度得到有效的控制;湿法小效应启动比较符合二次启动的特殊情况,而设定电压和效应都是后期管理中的控制关键。     

泡沫铅制备工艺研究

研究了电沉积法制备泡沫铅的工艺,以聚氨酯泡沫为基体,经脱脂-粗化-除膜-导电化处理后,先预镀铜然后再电沉积铅。在预镀铜过程中,考察了阴极电流密度、异极极距、镀液温度和电镀时间对电流效率和槽电压的影响,得到了最佳的镀铜工艺参数为：阴极电流密度3.0 A/dm2、异极极距3.5 cm、镀液温度为25℃、电镀时间35 min。在电沉积铅过程中,考察了铅离子浓度、氟硼酸浓度、添加剂、阴极电流密度及温度和时间等因素对电流效率、槽电压和泡沫铅产品质量的影响,确定了最佳工艺条件为：阴极表观电流密度3.0 A/dm2、镀液温度为25℃、电镀时间30～50 min。在优化条件下制备的泡沫铅镀层结晶细密、均匀,且韧性和光亮性都较好,孔隙率高,具有三维网状结构。     

从电子脚镀锡铜针中回收锡和铜

介绍了从电子脚镀锡铜针中回收锡和铜的工艺研究及生产实践。采用常温碱性电解脱锡,电解液无须加热循环流动,控制电流密度200A/m2、槽电压0.2⁰.4V,电解液含Sn 80.4V,电解液含Sn 8¹5g/L、NaOH 6015g/L、NaOH 60¹20g/L时,铜、锡的直收率分别达到99.7%和94.5%。脱锡铜针抛光处理后可以直接电解生产符合GB/T467-2010标准中Cu-CATH-1要求的阴极铜,电解条件:装填光亮铜针高出电解液面5cm以上,电流密度200A/m2,槽电压0.7V,电解液含Cu 45120g/L时,铜、锡的直收率分别达到99.7%和94.5%。脱锡铜针抛光处理后可以直接电解生产符合GB/T467-2010标准中Cu-CATH-1要求的阴极铜,电解条件:装填光亮铜针高出电解液面5cm以上,电流密度200A/m2,槽电压0.7V,电解液含Cu 45⁵0g/L、H2SO415050g/L、H2SO4150¹80g/L。