循环用阀控电池失效模式的研究

采用孔率测试、X射线衍射、电镜扫描等手段,对循环失效后的活性物质(AM)的成分与结构进行了较深入的研究,分析认为循环使用条件下,电池的失效主要是由正极活性物质(PAM)的软化、脱落所致。     

VRLA电池正极失效机理研究

通过对循环失效电池的解剖研究,发现造成电池失效的主要原因是正极活性物质软化与脱落。通过对失效电池正极板的X射线衍射(XRD)和扫描电镜(SEM)分析,表明:①随着循环的进行,β PbO2的颗粒尺寸逐渐变大,隔板失去弹性,正极板厚度逐渐增加,活性物质颗粒间的接触效果变差,电阻增加,最终导致电池容量的衰减和寿命终结;②大电流充电有利于形成更紧凑的正极活性物质骨架,对正极活性物质表面的结构有影响,有利于延长电池的循环寿命。     

电动自行车用铅酸蓄电池运行中失水对循环寿命的影响

在电动自行车铅酸蓄电池寿命循环过程中,正极活性物质软化和失水是蓄电池寿命失效的主要原因。活性物质中的杂质(腐殖酸含量)、较高充电电压以及较低安全阀开启压力,将加速失水,缩短蓄电池循环寿命。     

VRLA电池高倍率循环失效机理

VRLA电池普遍存在容量下降快、循环使用寿命稍短的缺点.对高倍率循环实验失效电池正极粉末进行了XRD、SEM分析及循环伏安测试,认为失效主要模式为正极活性物质软化脱落,造成活性物质失去部分活性及导电性.     

深循环用阀控铅酸蓄电池的失效机理

对深循环用阀控铅酸 (VRLA)蓄电池的失效机理进行了研究 ,对同批电池用不同的充电制度进行了寿命试验 ,并对失效电池进行解剖和X射线衍射分析。研究表明 :小电流恒压充电 ,电池失效的模式是负极硫酸盐化和正极活性物质软化 ;用优选充电制度 ,电池失效模式是正极活性物质软化 ,板栅腐蚀相对较少。对电池的失效机理进行了探讨 ,并提出了延长深循环用VRLA电池寿命的措施。     

VRLA电池循环失效的主要因素

对不同批次2 V2、00 Ah(C10=200 Ah)的VRLA电池单只和3只串联分别进行100%DOD循环实验。导致整组串联电池循环寿命提前结束的原因,主要是电池容量的均一性问题,落后的电池影响了循环寿命。对循环失效的电池进行解剖研究,发现造成电池失效的主要原因是正极活性物质的软化和脱落。     

铅酸蓄电池正极活性物质活性和失效模式

铅酸蓄电池循环寿命性能衰退通常由正极板性能降低所造成的，正极板的失效与正极活性物质的软化、正极板栅腐蚀和膨胀，以及正极板栅与活性物质界面纯化有关。讨论了正极活性物质的失效模式。     

通信用阀控密封铅酸蓄电池的早期容量损失

对通信行业中运行使用的阀控密封铅酸蓄电池失效模式进行了研究,对失效电池进行了解剖和X射线衍射、电镜扫描和化学等分析。研究结果表明:电池处于长期深放和充电不足等恶劣的使用环境,容易产生部分“落后电池”,这是一种典型的“早期容量损失(PCL)”现象,电池失效是由于正极活性物质形成“珊瑚状”结构,活性物质比表面积降低,可参与反应的活性物质数量减少,导致活性物质利用不足所致,这种可逆容量损失可以通过采用合适的循环制度,使失去的容量恢复。     

铅酸电池失效模式和机理分析研究进展

铅酸电池的失效导致电池使用寿命(容量)远低于预期年限,造成资源能源的巨大浪费和严重的安全问题。综述了铅酸电池失效模式和机理分析方面的研究进展,包括正极活性物质脱落,板栅腐蚀;负极不可逆硫酸盐化,高低温循环、高倍率部分荷电态(HRPSoC)对不可逆硫酸盐化的影响以及析氢等失效模式。     

18650型Li_4Ti_5O_(12)/LiCoO_2电池失效模式分析

采用参比电极确定18650型钛酸锂(Li_4Ti_5O_(12))/钴酸锂(LiCoO_2)电池在45℃下循环失效后的限容电极,对限容电极进行形貌、结构、交流阻抗及循环伏安等分析。电池失效后,充放电限容电极均为LiCoO_2正极;该电极失效的主要原因是活性物质结构被破坏,LiCoO_2的晶粒细化且内部微观应变较大,导致极片的界面性能下降及嵌脱锂动力学严重降低。     

Mechanical and electric fatigue of PZT(53/47) films on metallic substrates

Abstract

We have investigated the fatigue of electromechanical and dielectric properties of sol-gel derived PZT(53/47) thin films deposited on metallic substrates by means of electric and mechanical cycling. For the mechanical cycling a two point bending method was used to apply transversal stress to the samples. During mechanical cycling the piezoelectric coefficient d₃₁ remained constant up to about 10⁵ cycles, for a higher number of cycles a strong decrease was observed. During electric cycling no significant changes in the ferroelectric and electromechanical hysteresis loops could be found up to about 3×10⁵ cycles. Above this number the coercive field increases, the maximum strain and the remanent polarization decrease.

Obviously each electric cycling of the investigated films is accompanied by a mechanical cycling. It is assumed, that microcracks induced by mechanical stress are the main reason for the deterioration of the physical properties films during electric and mechanical cycling both.     

Thermal–Mechanical Coupling Analysis for Coupled Power- and Thermal-Cycling Reliability of Board-Level Electronic Packages

In this paper, we apply the sequential thermal-mechanical coupling analysis that solves, in turn, the transient temperature field and subsequent thermomechanical deformations to investigate thermal characteristics along with fatigue reliability of board-level thin-profile fine-pitch ball-grid-array chip-scale packages under coupled power- and thermal-cycling test conditions. Pure thermal-cycling and pure power-cycling test conditions are also examined and compared. From the comparison of different test conditions, we note that the presence of power cycling leads to significant deviations of junction and mold-top temperatures from the thermal-cycling profile. Nevertheless, for components away from the die, the deviations are less significant. As the power specified to the test vehicle is low, temperature histories on the components induced by coupled power and thermal cycling can be approximated by superposition of the temperature histories induced by pure power cycling and the ones by pure thermal cycling. For the test conditions proposed in this paper, pure power cycling leads to the longest fatigue life among all. For coupled power and thermal cycling, the involvement of power cycling reduces the fatigue life of the test vehicle by about 50% as compared to pure thermal cycling.     

Functional near infrared spectroscopy study of age-related difference in cortical activation patterns during cycling with speed feedback

Functional decline of lower-limb affects the ability of locomotion and the age-related brain differences have been elucidated among the elderly. Cycling exercise is a common training program for restoring motor function in the deconditioned elderly or stroke patients. The provision of speed feedback has been commonly suggested to clinical therapists for facilitating learning of controlled cycling performance and maintaining motivation in training programs with elderly participants. However, the cortical control of pedaling movements and the effect of external feedback remain poorly understanding. This study investigated the regional cortical activities detected by functional near infrared spectroscopy (fNIRS) in 12 healthy young and 13 healthy elderly subjects under conditions of cycling without-(free cycling) and with feedback (target cycling). The elderly exhibited predominant activation of the sensorimotor cortex during free cycling similar to young subjects but with poorer cycling performance. The cycling performance improved in both groups, and the elderly showed increased brain activities of the supplementary motor area and premotor cortex under target cycling condition. These findings demonstrated age-related changes in the cortical control in processing external feedback and pedaling movements. Use of fNIRS to evaluate brain activation patterns after training may facilitate brain-based design of tailored therapeutic rehabilitation strategies.     

铅酸蓄电池正极板深循环性能探讨

为提高蓄电池的深循环寿命性能 ,对电解液密度、板栅合金、电解液添加剂A等因素对正极板深循环性能的影响进行了实验探讨 ,发现电解液密度过高时对正极活性物质深循环性能有显著影响 ;专用合金I的深循环效果良好 ,但在板栅与活性物质界面仍会出现一定程度的钝化层 ,不利于蓄电池的深循环性能 ;电解液添加剂A对板栅与活性物质界面的钝化层有明显的改善作用 ,从而提高正极板深循环性能     

添加剂(RSO_3H)对铅酸蓄电池正极循环寿命的影响

测定了添加剂RSO3H对铅酸蓄电池正极充放电循环寿命的影响。结果表明，添加剂RSO3H可使正极的循环寿命缩短；若向正极铅膏中同时加入RSO3H和聚四氟乙烯（PTFE），则正极的循环寿命可以相对延长。     

汽车级IGBT模块功率循环及温度循环寿命对比与分析

随着电动汽车领域越来越多地使用绝缘栅极晶体管（IGBT）模块,在这些关乎乘员安全的场合,通常要求IGBT模块具有更高的可靠性。选取了典型的汽车级和工业级IGBT模块产品,分别进行了功率循环和温度循环试验,对比了2种模块的可靠性差异,结果表明,汽车级模块产品的功率循环寿命较工业级产品差,但是温度循环寿命明显优于工业级产品。     

电解液添加剂对金属锂电极的表面改性

为了提高金属锂二次电池中锂电极的性能,在电解液中添加了不同比例的1,4-二氧六环,测试了Li-LiCoO2扣式电池的性能。结果表明,在电解液中添加质量分数2%的1,4-二氧六环可使锂电极循环寿命大大增加,利用率增加10%,放电平台提高约100mV。与用1,4-二氧六环进行表面预处理电池相比,利用率和循环寿命差不多,但高次循环的放电平台可增加约80mV。而且,添加质量分数2%的1,4-二氧六环后电池的大电流放电性能也较好。     

Effect of P/E cycling on drain disturb in flash EEPROMs under CHE and CHISEL operation

Drain disturb is studied in NOR flash EEPROM cells under CHE and CHISEL programming operation, before and after repeated program/erase (P/E) cycling. Drain disturb is shown to originate from band-to-band tunneling under CHISEL operation, unlike under CHE operation where it originates from source-drain leakage. Under identical initial programming time, CHISEL operation always shows slightly lower program/disturb (P/D) margin before cycling but similar P/D margin after repetitive P/E cycling when compared to CHE operation. The degradation of gate coupling coefficient that affects source/drain leakage and the increase in trap-assisted band-to-band tunneling seems to explain well the behavior of CHE and CHISEL drain disturb after cycling.     

Control strategies for integration of electric motor assist and functional electrical stimulation in paraplegic cycling: utility for exercise testing and mobile cycling

AIM: The aim of this study was to investigate feedback control strategies for integration of electric motor assist and functional electrical stimulation (FES) for paraplegic cycling, with particular focus on development of a testbed for exercise testing in FES cycling, in which both cycling cadence and workrate are simultaneously well controlled and contemporary physiological measures of exercise performance derived. A second aim was to investigate the possible benefits of the approach for mobile, recreational cycling. METHODS: A recumbent tricycle with an auxiliary electric motor is used, which is adapted for paraplegic users, and instrumented for stimulation control. We propose a novel integrated control strategy which simultaneously provides feedback control of leg power output (via automatic adjustment of stimulation intensity) and cycling cadence (via electric motor control). Both loops are designed using system identification and analytical (model-based) feedback design methods. Ventilatory and pulmonary gas exchange response profiles are derived using a portable system for real-time breath-by-breath acquisition. RESULTS: We provide indicative results from one paraplegic subject in which a series of feedback-control tests illustrate accurate control of cycling cadence, leg power control, and external disturbance rejection. We also provide physiological response profiles from a submaximal exercise step test and a maximal incremental exercise test, as facilitated by the control strategy. CONCLUSION: The integrated control strategy is effective in facilitating exercise testing under conditions of well-controlled cadence and power output. Our control approach significantly extends the achievable workrate range and enhances exercise-test sensitivity for FES cycling, thus allowing a more stringent characterization of physiological response profiles and estimation of key parameters of aerobic function. We further conclude that the control approach can significantly improve the overall performance of mobile recreational cycling.     

锰酸锂充放电过程中的化学变化

为了考察LiMn2O4锂离子蓄电池正极材料在充放电过程中的化学变化,采用高温固相法制备了尖晶石型LiMn2O4,并对其电化学性能进行了表征,利用X射线衍射分析的结果,结合Li-Mn-O相图,对LiMn2O4在多次循环充放电所发生的相变进行了研究。实验结果表明,其首次放电比容量为123 mAh/g,循环200次后的放电比容量为107 mAh/g;LiMn2O4发生歧化反应,以及在LiMn2O4微粒表面形成的Li2Mn2O4进一步转化成无电化学活性的Li2MnO3,这两种相变都会导致电池的不可逆容量损失。