锰酸锂晶体显微结构对电池电气性能的影响

介绍了不规则锰酸锂、球形锰酸锂和单晶锰酸锂三种不同形貌锰酸锂的合成工艺。采用显微图像测试方法对样品形貌及结构进行测试,研究它们的性能。对分别使用三种锰酸锂作为原材料制备而成的纽扣电池、软包电池进行电池循环、差热分析法(DTA)等测试,分析材料形貌在材料结构和热稳定性方面的作用。测试结果表明,单晶锰酸锂(LMO)综合性能最佳,尤其循环性能和热稳定性;不规则LMO各项性能指标均表现不佳;球形LMO多数性能指标居中,除倍率放电能力最优。     

磁控溅射制备V2O5薄膜及全固态薄膜锂电池研究

V_2O_5具有容量高、循环稳定、易于制备成薄膜等特点,是全固态薄膜锂电池理想的正极材料。采用磁控溅射法,以V_2O_5为靶材制备了薄膜,研究了溅射气体Ar/O_2对薄膜结构、形貌及电化学性能的影响,优化了薄膜制备工艺。最终采用磁控溅射法依次沉积集流体薄膜、钒氧化物薄膜、固态电解质薄膜,真空热蒸发金属锂薄膜,成功制备了Al/V_2O_5/Li P ON/Li/Cu全固态薄膜锂电池。薄膜电池在1.7～3.4 V电压范围内,以10μA/cm~2恒电流充放电测试,电池比容量达到25μAh/cm~2,稳定循环超过500次。     

层状锰酸锂/碳电化学体系的热稳定性模拟

通过对满电态层状锰酸锂材料、全放电态碳材料及电解液的热性质分析和拟合,建立了层状锰酸锂/碳电化学体系的热模拟模型,并对该体系的热稳定性进行了模拟研究。通过研究该电池从缓慢自放热到热失控的整个过程发现,满电态的层状锰酸锂材料和全放电态碳材料都有两个放热反应过程;负极碳材料在120℃左右的放热峰是造成电池自加热的初始原因,而层状锰酸锂和碳材料300℃左右的放热峰是造成该电池体系热失控的主要原因。该研究对层状锰酸锂/碳电池体系的安全设计与评估提供了理论支持。     

喷雾法制备FeS_2薄膜材料及其在热电池中的性能

采用喷雾法薄膜化工艺制备了FeS_2薄膜正极,研究了薄膜正极中导电剂(超导炭黑)的添加量对热电池单体电池放电性能的影响。以异丙醇为溶剂,适量的超导炭黑为导电剂,采用喷雾法制备热电池FeS_2薄膜正极。与传统的压片制备FeS_2阴极相比,喷雾法合成的黄铁矿薄膜厚度小,在放电过程中有较高的放电比容量。在500℃,相对湿度RH1%的条件下,测试了单体电池的放电性能。测试结果表明,5%XC-72R掺杂FeS_2材料的单体电池的放电比容量最高。     

LED球泡灯相关专利简介(4)

正(续上期)29人体热释电感应灯电路摘要:本发明公开了1种人体热释电感应灯电路,包括阻容降压电路,所述的阻容降压电路通过线路与热释电红外感应电路相连,所述的热释电红外感应电路通过线路与感应头功能电路相连;所述的感应头功能电路通过线路与阻容降压电路相连。     

LiMn2O4薄膜的溶胶-凝胶法制备及其电化学性质

以醋酸锂、醋酸锰、乙二醇甲醚和乙酰丙酮为原料,采用溶胶 凝胶法制备薄膜锂离子蓄电池正极材料尖晶石LiMn2O4薄膜。用X射线衍射、扫描电镜分析了薄膜的物相和表面形貌,用循环伏安法、充放电和交流阻抗技术研究了薄膜的电化学性能。结果表明该法制备的LiMn2O4薄膜均匀、无开裂,750℃退火5min得到的薄膜的首次放电容量为36μAh/(cm2·μm),经100次循环后每次循环的容量损失为0.037%,薄膜具有良好的电化学性能。     

混合式光电电流互感器数据采集系统的设计

设计了一种混合式光电电流互感器数据采集系统。采用16位微功耗高速A／D芯片ADS8325及控制器件EPM240Z芯片设计了硬件电路,给出了A／D控制程序流程、仿真波形,并分析了测试结果,测量精度符合IEC0．2级标准。该系统具有低功耗、高性能及良好的电隔离性。     

制备层状LiMnO2的水热合成法工艺优化

正交层状锰酸锂(o-LiMnO_2)是高能量密度锂离子电池正极材料之一,是当前的研究热点。利用水热合成法制备层状锰酸锂,颗粒细小,形状均匀,更利于电池的装填。但是,水热法制备锰酸锂需要在较高的锂锰比下进行,造成了锂资源的浪费,也阻碍了工业化生产的进行。在水热合成过程中通过添加氨水,成功地在低锂锰比条件下制备出o-LiMnO_2,该工艺对o-LiMnO_2的工业化生产具有重大指导意义。     

一种热释电红外线传感器的应用

利用热释电红外线传感器,设计家用防盗报警系统的应用日益广泛。讨论了无线电感应、发射、接受、报警系统的构成,并结合应用电路分析了热释电红外线传感器工作性能,对利用热释电红外线传感器设计新型的家用防盗装置有一定的借鉴作用。     

18650型锂离子电池的安全性能研究

用质量比为5∶5和7∶3的锰酸锂和包覆镍酸锂混合的复合材料作为正极,球形石墨作为负极,制成18650型锂离子电池并进行了安全性测试。结果表明:在热箱实验中,复合材料组装的电池可以耐145~150℃的高温,且在3C、10 V和5C1、0 V过充电条件下安全可靠。随着复合材料中锰酸锂比例的增加,电池的安全性提高。在电池内装置正温度系数端子(PTC),可提高电池的耐过充性和短路安全性。     

Precursor design for liquid Injection CVD of lead scandium tantalate thin films

Abstract

Liquid Injection Chemical Vapour Deposition is a technique well suited to the deposition of a range of ferroelectric oxides in thin film form. This paper reports on the design and optimisation of the precursors for the deposition of thin films of the promising pyroelectric material, lead scandium tantalate. The design and use of lead, scandium and tantalum precursors with carefully matched chemical and thermal properties allows the growth of thin films with the required perovskite phase above 550°C. These have the desired 111 orientation when grown on to platinum coated silicon substrates at temperatures above 575°C.     

Piezo- and pyroelectric properties of lead scandium tantalate thin films

Abstract

This paper discusses the piezo- and pyroelectric properties of lead scandium tantalate thin films prepared by modified sol-gel technology. Films were deposited on Pt/Ti/SiO₂/Si-sub-strates at 530–630 °C. The quality of the thin films was optimized by design of both the deposition conditions and the solution chemistry. These approaches include spin coating speed, drying plus crystallization temperature and time, drying atmosphere, the use of rapid thermal annealing, PST sol composition, Pb-excess concentration and mixing method. The finished thin films were characterized by optical microscopy, X-ray diffraction, atomic force microscopy, and pyroelectric measurements at 30°C under a DC-bias. Piezo-response AFM was conducted on PST to monitor various piezoelectric responses, which depend on the micro-structure of the film. The maximum pyroelectric figure-of-merit F_D was 3.85×10^?5 Pa^?1/2 at 30°C and 1 kHz under a 35 V DC-bias.     

Thin ferroelectric films for thermal detector applications

Abstract

The deposition of thin films of lead scandium tantalate (Pb(Sc_1/2Ta_1/2O₃) have been investigated by two processing routes. In the first, progress is reviewed for chemical vapour deposition in a purpose built low pressure reactor, utilising suitable modified proprietary precursors. Deposition has been studied over the temperature range 400–800°C and, in general, amorphous films result which convert to crystalline perovskites on subsequent annealing. However, inclusion of hydroxy compounds in the vapour train catalyses the crystallisation process and enhances the growth rate at above 600°C. It was found that the best thin films, in terms of density and morphology, are formed at low deposition rates 1–2μm/hr. The perovskite phase is obtained if the gas phase composition is controlled throughout growth. The choice of precursors, gas compositions and growth conditions will be described. In the second process, lead scandium tantalate thin films (1μm) were deposited using a modified sol-gel solution route. This was achieved by spin-coating a solution of metallo-organic compounds of scandium and tantalum followed by lead, onto suitable substrates and firing and annealing the films at 800–1000°C. These firing temperatures gave films with grain sizes ranging from 0.5–4μm, which are single phase perovskite. Permittivity, dielectric loss and field induced pyro-electricity have been measured against field and temperature to assess the pyroelectric figure-of-merit, F_D of films obtained from both film deposition process. The F_D for sol-derived films indicates a performance similar to that of bulk ceramic material.     

Pyroelectric detectors and their applications

The authors review the principles of operation of pyroelectric detectors. The equations for current responsivity, voltage responsivity, noise, noise equivalent power, and detectivity are derived from the fundamental thermodynamic model of a pyroelectric detector. The frequency-dependent current and voltage responsivities are explained. Factors influencing the choice of pyroelectric material for various applications are summarized. The possibilities of various new applications and the developments of pyroelectric detectors are discussed. A laboratory prototype demonstration system has been built using an ELTEC detector type 5192. For a high signal-to-noise ratio, an electric charge integration technique is applied. High-precision operational amplifiers are used for high-quality signal conditioning. The pyroelectric detector consists of two parallel opposed dual lithium tantalate pyroelectric single crystals with a junction FET source follower sealed in a standard TO-5 housing     

Pyroelectric Thin Film Presence Detector Arrays with Micromachined Pixels

Lately, pyroelectric thin film detectors gain in significance in the field of presence detection. In the paper, different variants of Pb(ZrTi)O 3 based detector arrays with 8 to 256 pixels are introduced. The sensing elements are arranged on thin micromachined SiO 2 /Si 3 N 4 membranes [1-4] as mechanical supporting structure with both low thermal mass and low heat conductivity into the substrate to achieve a high detectivity. For shaping these membrane structures, the most promising technology is micromachining, either from back or from surface of the silicon substrate. Self-polarized PZT thin films with a pyroelectric coefficient p up to 2.1 * 10 m 4 C/(m 2 K), dielectric loss tan i of less than 0.01 and a dielectric coefficient l r of about 250 are deposited in a multi-target sputtering process at comparatively low substrate temperatures of about 520°C. In the paper, presence detectors using thin film pyroelectric IR detector arrays as well as detector design, detector simulation, detector manufacturing and detector characteristics are discussed. In addition, pyroelectric material investigations and preparation of micromachined structures in combination with the back-end process of the pyroelectric active capacitor structure are presented.     

Effect of Thermal Treatment Temperature on the Crystallinity and Morphology of LiTaO3 Thin Films Prepared from Polymeric Precursor Method

Lithium tantalate thin films (LiTaO₃) with (50:50) stoichiometry were prepared by spin coating method using a polymeric organic solution. The films were deposited on silicon (100) substrates with 4 layers. The substrates were previously cleaned and then the solution of lithium tantalate was deposited by adjusting the speed at 5000 rpm. The thin films deposited were thermally treated from 350 to 600C for 3 hours in order to study the influence of the thermal treatment temperature on the crystallinity, microstructure, grain size and roughness of the final film. X-ray diffraction (XRD) results showed that the films are polycrystalline and secondary phases free. The thickness of films was observed by scanning electron microscopy (SEM). The atomic force microscopy (AFM) studies showed that the grain size and roughness are strongly influenced by thermal treatment.     

Effects of thickness of the thermal insulation layer on the properties of PbTiO3 thin films

A multilayer pyroelectric thin film structure (MPTFS) is one of promising candidates for applications on uncooled IR focal plane array detectors. In the MLPTFS, a porous silica film is used as a thermal insulation layer, and the thermal insulation is improved with increasing thickness of a porous silica film. On the other hand, the effects of thickness of the porous silica films on the electrical properties of pyroelectric thin films need to be addressed. The research results have shown: the thickness of the porous silica films can not be increase unboundedly. With increasing thickness of porous silica films, the coercive field increase, the dielectric constant and the breakdown field decrease respectively. When the thickness of the porous silica films is lower than 3 μm, the effects of the porous silica films on the properties of PT thin films are acceptable. The optimized thickness of the porous silica films is determined according to the results of the electrical properties.     

Preparation and properties of Pb(Zr, Ti)O3 ferroelectric thin films and compositionally graded thin films on LaNiO3/Si substrates

LaNiO₃ (LNO) thin films were prepared on Si (100) wafer by MOD method. Pb(Zr, Ti)O₃ ferroelectric thin films and their compositionally graded thin films were prepared on LNO/Si (100) substrates by a modified sol–gel method. The composition depth profile of a graded film was determined by using a combination of Auger electron spectroscopy and Ar ion etching. The results confirmed that the processing method produces graded composition change. XRD analysis showed that the graded thin film possessed a composite structure of tetragonal and rhombohedral. The dielectric constant of the graded thin films was higher than that of each thin film unit, but the loss tangent was near to each other at 10 kHz. The temperature characteristics of the dielectric constant of the graded thin films at different frequencies showed three peaks and ferroelectric relaxor feature to some extent. Hysteresis loops showed that graded thin film had higher remanent polarization, smaller coercive field than each thin film unit. The pyroelectric coefficient of the graded thin films increased gradually with temperature, and was higher than that of each thin film unit.     

Optical Properties of LiTaO3 Thin films crystallized by RTA processes

High-performance pyroelectric infrared detectors have been fabricated using Lithium tantalite (LiTaO₃) thin films deposited on Pt(111)/Ti/SiO₂/Si(100) substrates by diol-based sol-gel method and rapid thermal annealing (RTA) technique. The dielectric and pyroelectric properties of IR detectors of LiTaO₃ thin films crystallized by conventional and RTA processes are investigated. Experimental results reveal that the heating rate will influence strongly on dielectricity and pyroelectricity of LiTaO₃ thin films. The voltage responsivities (Rv) measured at 80 Hz increase from 5496 to 8455 V/W and the specific detecivities (D^∗) measured at 300 Hz increase from 1.94 × 10⁸ to 2.38 × 10⁸ cmHz^1/2/W with an increase of heating rate from 600 to 1800^∘C/min. However, the voltage responsivity and the specific detecivity decrease with heating rate in excess of 1800^∘C/min. The results show that the LiTaO₃ thin film detector with a heating rate of 1800^∘C/min exists both the maximums of voltage responsivity and specific detecivity.     

薄膜锂电池制备工艺现状

随着无线电通讯和集成光电路的迅速发展 ,在很多电子设备上都要求有独立的高性能微型电源。薄膜锂电池作为一种重要的微型能源形式 ,正在受到越来越多的关注和研究。概述了国际上目前制备薄膜锂电池的阴极膜、阳极膜和电解质膜过程中所采用的各种工艺手段 ,从工作原理、采用的材料与设备、得到的膜的物理化学性能等各个方面对这些工艺方法进行了分析、比较及评价