长寿命软包装钛酸锂/锰酸锂锂离子电池性能

以钛酸锂为负极、锰酸锂为正极制作了软包装锂离子电池,分析了钛酸锂/锰酸锂电池在充放电过程中产生的气体成分,研究了影响钛酸锂电池胀气的因素,如钛酸锂材料、电解质溶液酸度、电解质溶液添加剂等。进一步开发出性能优越的35 Ah软包装钛酸锂/锰酸锂电池,该电池常温1 C循环3 000次后容量保持87%,高温55℃、1 C、1 300次循环后仍能保持85%的初始容量,并具有良好的倍率性能和搁置性能。     

LiMn_2O_4/Li_4Ti_5O_(12)锂离子电池的制备及电化学性能的研究

采用商品化的LiMn2O4和Li4Ti5O12作为正负极材料制作锰酸锂-钛酸锂锂离子电池,研究了不同正负极容量配比对锰酸锂/钛酸锂锂离子电池的循环性能、自放电性能、高温搁置性能以及正负极活性物质的克容量发挥的影响,并利用扫描电子显微镜法(SEM)和能量散射光谱(EDS)表征循环900周后电池负极极片的形貌和成分。研究结果表明:正负极容量配比大的电池各方面性能要优于正负极容量配比小的电池。     

新型(LiFeO4+LiMn2O4)/(Li4Ti5O12+CNTS)锂离子电池的制备

用磷酸铁锂和锰酸锂复合材料作为锂离子电池的正极活性物质,与钛酸锂碳纳米管复合负极材料匹配制备了新型锂离子电池.锰酸锂提高了电池的放电电压和容量,碳纳米管提高了负极的电导率.电池循环性能良好,经100次循环后容量保持率为98.8％.     

锂离子电池负极材料Li_4Ti_5O_(12)研究进展

尖晶石型结构的钛酸锂是一种"零应变"材料,循环性能优良,充放电电压稳定,是最有应用价值的锂离子电池负极材料之一。介绍了钛酸锂材料的研究发展历程,晶体结构特点;综述了钛酸锂的几种制备方法,并对钛酸锂的掺杂改性进行了探讨和概述,提出了目前存在的问题并对其前景进行了展望。     

反尖晶石离子掺杂对LiMn2O4结构性能的影响

阐述了锂离子电池锰酸锂正极材料掺杂的重要性,研究了反尖晶石离子掺杂(Fe3 、Ga3 、Al3 )对锰酸锂正极材料结构和电化学性能的影响,并提出了影响锂离子电池充放电循环性能的机理。展望了反尖晶石离子掺杂在锂离子电池锰酸锂正极材料中的发展前景。     

功率型LiNi_(0.5)Mn_(1.5)O_4正极材料的研究进展

电动汽车等高功率用电终端对提高锂离子电池的工作电压提出了更高要求,镍锰酸锂因具有4.7 V的放电电压而成为高功率锂离子电池正极材料的首选。综述了镍锰酸锂正极材料的结构特点、制备方法,并介绍了通过掺杂,包覆和控制形貌来提高其倍率、循环等电化学性能的研究进展,为功率型锂离子电池的研发提供了参考。     

LiFePO4/Li4Ti5O12锂离子电池的制备及研究

使用磷酸铁锂(LiFePO4)和钛酸锂(Li4Ti5O12)做正、负极活性材料,制备锂离子电池,并测试其性能。用三电极法考察不同配比时正负电极充放电电位的变化,并据此确定了电池中正负极的容量配比。性能测试结果表明,所制备的锂离子电池具有优异的循环稳定性,容量发挥好。正负极容量配比1.4时,18650圆柱电池负极钛酸锂的容量发挥为160mAh/g。     

高倍率LiMn_2O_4锂离子电池的制作与性能

采用商品化的LiMn2O4和石墨作为正极材料制作锰酸锂动力电池,并利用XRD、SEM等分析手段表征了LiMn2O4原料。研究了不同面密度和导电剂含量对锰酸锂电池倍率性能的影响。研究发现,锰酸锂电池的倍率性能随着面密度的减小而改善,随着导电剂含量的增加先改善后变差。当正极面密度未2.5 g/dm2,导电剂含量为3%时电池的倍率性能最好。20 C放电容量为1 C的94.1%,1C充电5 C放电,100次循环后容量保持率为92%。     

以Li_4Ti_5O_(12)作负极的聚合物锂离子电池的性能

应用纳米级钛酸锂粉末作为负极活性材料制作聚合物锂离子电池,并对电池进行测试.分析和评价了其电压特性、倍率充电特性、倍率放电特性、低温放电特性、循环寿命以及安全性能,同时与石墨负极的聚合物锂离子电池进行了比较.研究表明,钛酸锂负极的聚合物锂离子电池在安全性能、倍率充放电性能、低温特性等方面超过石墨负极的聚合物锂离子电池,能够适合于在混合动力汽车和电动汽车上的应用.但电池的能量密度需要进一步提高,同时制作的成本需要进一步降低.     

1865140型(LiMn2O4+LiNi1/3Co1/3Mn1/3O2)/Li4Ti5O12电池的性能

使用锰酸锂(LiMn2O4)、镍钴锰酸锂(LiNi1/3 Co1/3Mn1/3O2)混合正极材料和钛酸锂(Li4 Ti5 O12)负极材料,制备了中倍率1865140型锂离子电池.制备的电池在12 min内可充满电池容量的80％以上,且电池表面温度不超过35℃;在室温下以2.00 C循环1 200次,容量保持率高于91％;在高温55℃下以1.00 C循环1 000次,容量保持率高于82％.FreedomCAR混合脉冲功率特性表明:在放电深度(DOD) 10％ ～ 70％内、10s脉冲充放电状态下,电池的阻抗都在9 mΩ以下;50％DOD时的10s放电比功率为372 W/kg,充电比功率为520 W/kg.     

球形四氧化三锰合成锰酸锂的性能

分别以湿法沉淀的球形四氧化三锰(Mn3O4)和商业电解二氧化锰(EMD)为锰源合成锰酸锂(Li Mn2O4)。通过杂质含量分析、XRD、SEM和充放电测试等,研究锰源对产物性能的影响。以粒度为10μm的球形Mn3O4为原料合成的Li Mn2O4保留了锰源的物化特征,以1.0 C在3.00~4.35 V充放电,首次放电比容量为117.2 m Ah/g,常温、55℃高温循环100次的容量保持率分别为94.6%和91.0%,高于以EMD为原料合成的Li Mn2O4(分别为87.9%和72.9%)。循环性能的提高,与球形Li Mn2O4的粒度分布集中、比表面积小及杂质含量低有关。     

Electrophoretic deposition of SrBi4Ti4O15 thick films on Al2O3 substrate

Electrophoretic deposition (EPD) is a powerful route to obtain thick films onto conductive substrate. In this work, ferroelectric SrBi₄Ti₄O₁₅ films up to 15 μm were prepared by EPD using submicrometer SrBi₄Ti₄O₁₅ (SBT) powders. The ethanol was used as the solvent with addition of HCl and PVB (dispersant). The zeta potential of SBT powder in ethanol is low compared to some other ceramics such as PZT, so it tends to flocculate and is more difficult to be deposited. With addition of PVB, the suspension was then stabilized. The deposition kinetics and the effect of additives were observed and discussed using DLVO theory. From SEM and XRD observation, the films obtained were crack-free and grain-oriented.     

FERROELECTRIC,PIEZOELECTRIC AND DIELECTRIC PROPERTIES OF Nb MODIFIED Bi4Ti3O12-SrBi4Ti4O15 INTERGROWTH

ABSTRACT

Doping and constructing intergrowth are found to be an effectual approach to modify the electrical properties of bismuth layer-structured ferroelectrics. In this work, ferroelectric, piezoelectric and dielectric properties of Nb-doped Bi₄Ti₃O₁₂-SrBi₄Ti₄O₁₅ (BTN-SBTN-x) intergrowth ceramics were investigated. The ferroelectric property of Bi₄Ti₃O₁₂-SrBi₄Ti₄O₁₅ was improved by niobium doping. The remanent polarization (2P _r ) increases at first, then decreases with the increase of niobium content, while the coercive field changes little with Nb-doping. As niobium content is 0.06, the 2P _r maximizes at a value of 34.9 μC/cm², which is increased by about 75% in comparison with that of Bi₄Ti₃O₁₂-SrBi₄Ti₄O₁₅ (2P _r = 20.0 μC/cm²). The Curie temperature of the samples varies hardly upon Nb-doping, which indicates that the good thermal stability of Bi₄Ti₃O₁₂-SrBi₄Ti₄O₁₅ is not deteriorated after Nb addition. Piezoelectric coefficient d₃₃ was increased from 9.3 pC·N^?1 to 18.6 pC·N^?1 due to the enlargement of 2P _r .     

Ferroelectric versus Relaxor Behaviour in Na0.5Bi4.5Ti4O15—BaBi4Ti4O15 Solid Solutions

Sodium-bismuth titanate Na_0.5Bi_4.5Ti₄O₁₅ (NBT) and barium bismuth titanate BaBi₄Ti₄O₁₅ (BBT) and their solid solutions were prepared by solid state reaction of the constituent oxides. The room temperature structural characteristics were determined by X-ray diffraction and the dielectric properties investigated in a wide range of temperatures (20–750°C) and frequencies (1 kHz–1 MHz). As the barium content increases, the unit cell change from orthorhombic to pseudo-tetragonal, the paraelectric to ferroelectric phase transition decreases from 655°C to 400–420°C and a relaxor-like behaviour is observed for high barium contents. Depending on the composition, dielectric data were fitted using both classical (low Ba) and modified Curie-Weiss law for relaxors (high Ba).     

尖晶石型LiMn2O4的制备

研究开发了一种新的溶胶-凝胶法制备LiMn2O4的技术,运用热分析、红外光谱、X射线衍射、比表面积测定等技术研究了前驱体及产物的结构和形貌特点,探讨了煅烧温度、螫合剂用量对LiMn2O4结构、表面形貌及充放电性能的影响.     

Effect of CoFe2O4 content on the dielectric and magnetoelectric properties in Pb(ZrTi)O3/CoFe2O4 composite

Ferroelectric Pb(Zr_0.53Zr_0.47)O₃ (PZT) and ferromagnetic CoFe₂O₄ (CFO) composite ceramics, [(1???x)PZT???xCFO for x?=?10, 20, 30, 40 and 50 wt.%], were prepared by a conventional solid-state reaction method. X-ray diffraction studies revealed that only PZT and CFO phases were present in the composite samples and no other phase was detected. The 0.9PZT-0.1CFO composite ceramic displayed better piezoelectric properties. The piezoelectric resonance frequency increased with the CFO content, but the resonance peak attenuated rapidly and disappeared when the CFO content equaled to 0.5. The permittivity peak temperature was the same as that of pure PZT ceramics. 0.9PZT-0.1CFO composite also had the highest magnetoelectric (ME) coupling coefficient among the studied PZT-CFO composite ceramics. The ME coefficient linearly increased with ac frequency up to 100 kHz.     

Electrical and optical characterization of Ag2V4O11 and Ag4V2O6F2

The two silver vanadium oxide phases—Ag₂V₄O₁₁ and Ag₄V₂O₆F₂—were prepared by hydrothermal synthesis. The electrical conductivity of both silver vanadate powders was determined by the powder-solution-composite (PSC) method. The conductivities obtained were 0.0085 ± 0.0005 and 0.0005 ± 0.00015 S/cm for the Ag₂V₄O₁₁ and Ag₄V₂O₆F₂, respectively, the first such report for the Ag₄V₂O₆F₂ phase. The optical gap and the transmission where studied by diffuse reflectance. Both were larger for Ag₄V₂O₆F₂ than Ag₂V₄O₁₁, concomitant with a decrease in carrier content.     

Fe3O4磁性流体的制备

采用胶溶法（或称溶胶法）制备Ｆｅ３Ｏ４磁性流体,研究了不同包覆温度,不同包覆酸度对Ｆｅ３Ｏ４粒吸附油酸量的影响;不同分散温度,不同载液对磁性能的影响,得出了最佳工艺参数,测量了所制备的磁流体的主要性能参数,并进行了实际的密封实验,证明所制磁流体的性能优良,能较好地用于旋轴密封水和油。     

Co_3O_4修饰Li_4Ti_5O_(12)的制备及电化学性能研究

通过简单的湿法球磨混合工艺,经过低温热处理得到Co3O4修饰Li4Ti5O12复合材料。通过X射线衍射光谱法(XRD)、扫描电子显微镜法(SEM)、能量散射光谱(EDS)、恒电流充放电测试、循环伏安(CV)以及交流阻抗(EIS)对材料的结构、形貌、组成及电化学性能进行表征。结果表明,Co3O4修饰没有改变Li4Ti5O12的尖晶石结构,以小颗粒的形式分布在材料中。Co3O4修饰增强了材料的电化学活性,减小了电极极化,使得材料的电化学性能得到提高。其中1%(质量分数)的Co3O4修饰Li4Ti5O12显示出较好的倍率性能和循环稳定性,0.2 C下的首次放电比容量为174 m Ah/g,2 C下循环300次后比容量为128.2 m Ah/g,容量保持率为95.6%。