Achieving Synergistic Improvement in Dielectric and Energy Storage Properties of All-Organic Poly(Methyl Methacrylate)-Based Copolymers Via Establishing Charge Traps

How to achieve synergistic improvement of permittivity(ε_(r))and breakdown strength(E_(b))is a huge challenge for polymer dielectrics.Here,for the first time,theπ-conjugated comonomer(MHT)can simultaneously promote theε_(r)and E_(b)of linear poly(methyl methacrylate)(PMMA)copolymers.The PMMA-based random copolymer films(P(MMA-co-MHT)),block copolymer films(PMMA-b-PMHT),and PMMA-based blend films were prepared to investigate the effects of sequential structure,phase separation structure,and modification method on dielectric and energy storage properties of PMMA-based dielectric films.As a result,the random copolymer P(MMA-coMHT)can achieve a maximumε_(r)of 5.8 at 1 kHz owing to the enhanced orientation polarization and electron polarization.Because electron injection and charge transfer are limited by the strong electrostatic attraction ofπ-conjugated benzophenanthrene group analyzed by the density functional theory(DFT),the discharge energy density value of P(MMA-co-PMHT)containing 1 mol%MHT units with the efficiency of 80%reaches15.00 J cm^(-3)at 872 MV m^(-1),which is 165%higher than that of pure PMMA.This study provides a simple and effective way to fabricate the high performance of polymer dielectrics via copolymerization with the monomer of P-type semi-conductive polymer.

A review of neutral pH polymer electrolytes for electrochemical capacitors:Transitioning from liquid to solid devices

The development of neutral pH polymer electrolytes has enabled high-performance solid-state,thin,and flexible electrochemical capacitors(ECs)to provide power for future consumer electronics and Internet-of-Thing devices.Notwithstanding their promising prospect,there is still some lack of understandings or disconnections from fundamental science to practical applications of these electrolytes.In this review,we provide an overview of stateof-the-art studies on ECs with neutral pH electrolytes in both liquid and solid configurations.Starting from the fundamental studies on the voltage window and ion conduction of salt species in liquid solution to polymer electrolytes,key considerations in developing neutral pH polymer electrolytes are discussed.The performance of the polymer electrolytes along with their enabled solid symmetric and asymmetric EC devices,as well as some enhanced functionalities are presented.The future directions for research on neutral pH polymer electrolytes are proposed,expected to provide reference for further enriching the fundamental knowledge and improving the device performances.

Vapor Phase Polymerization Deposition Conducting Polymer Nanocomposites on Porous Dielectric Surface as High Performance Electrode Materials

We report chemical vapor phase polymerization(VPP) deposition of poly(3,4-ethylenedioxythiophene)(PEDOT) and PEDOT/graphene on porous dielectric tantalum pentoxide(Ta_2O_5) surface as cathode films for solid tantalum electrolyte capacitors. The modified oxidant/oxidant-graphene films were first deposited on Ta_2O_5 by dip-coating, and VPP process was subsequently utilized to transfer oxidant/oxidant-graphene into PEDOT/PEDOT-graphene films. The SEM images showed PEDOT/PEDOT-graphene films was successfully constructed on porous Ta_2O_5 surface through VPP deposition, and a solid tantalum electrolyte capacitor with conducting polymer-graphene nano-composites as cathode films was constructed. The high conductivity nature of PEDOT-graphene leads to resistance decrease of cathode films and lower contact resistance between PEDOT/graphene and carbon paste. This nano-composite cathode films based capacitor showed ultralow equivalent series resistance(ESR) ca. 12 m? and exhibited excellent capacitance-frequency performance, which can keep 82% of initial capacitance at 500 KHz. The investigation on leakage current revealed that the device encapsulation process has no influence on capacitor leakage current, indicating the excellent mechanical strength of PEDOT/PEDOT-gaphene films. This high conductivity and mechanical strength of graphene-based polymer films shows promising future for electrode materials such as capacitors, organic solar cells and electrochemical energy storage devices.

Electrical Shorting between the Carbon-Fiber Cloth Electrodes of Structural Capacitors with a Glass-Fiber Cloth Separator

Multifunctional composites that have the ability to store or generate energy have attracted huge attention recently. One type of multifunctional composite is a structural capacitor that uses carbon fiber cloth as electrodes separated by glass-fiber cloth. However, such structural capacitors are difficult to fabricate reliably because electrical shorts sometimes form between the electrodes. In the present study, we investigate the mechanism of electrical shorting in such capacitors, which allows us to propose an improved fabrication process to prevent electrical shorting between the carbon-cloth electrodes. Infrared thermography reveals that electrical shorting between the electrodes is caused by contact between the carbon-fiber electrodes. Such contacts are formed by movement of the glass fibers of the separator during curing, which is induced by epoxy resin flow. Pre-curing of the glass-fiber cloth separator to a suitable degree ensures that the electrical insulation between carbon-fiber electrodes is reliable.

Fabrication and Characterization of Semi-Crystalline and Amorphous Dielectric Polymer Films for Energy Storage

Dielectric polymer films are energy storage materials that are used in pulse power operations, power electronics and sustainable energy applications. This paper reviews energy storage devices with focus on dielectric film capacitors. Two prominent examples of polymer dielectrics Polyetherimide (PEI) and Poly (tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride) (THV) have been discussed. Polyetherimide (PEI) is an amorphous polymer recognized for its high-temperature capability, low dielectric loss and high dielectric strength. THV is a semi-crystalline polymer with high dielectric constant, high-temperature capability and charge-discharge efficiency. The primary focus of this paper is to introduce the reader to the fabrication procedures and characterization techniques used in research labs for processing of dielectric polymers. The fabrication and characterization process of both polymers has been discussed in detail to shed the light on experimental process in this area of research.

基于电介质薄膜的器件自愈性能的研究现状

随着能源与电力技术的不断发展,对电容器的需求越来越大,而各种资源的稀缺强调了利用各种能源的必要性,对于各种储能器件如金属化薄膜电容器以及基于电活性聚合物(electroactive polymers,EAP)的能量转换装置提出了更高的要求。然而这两类装置却极易发生电击穿,在工作循环中有着极高的故障率,因此器件的自愈性具有十分重要的意义。文中综述了金属化薄膜电容器和EAP能量转换装置自愈性能的国内外研究现状,首先重点关注了金属化薄膜电容器中自愈理论发展以及各种关键参数对自愈的影响,其自愈最为稳定且研究相对完善。随着介电弹性体的兴起,想要其拥有自愈性能,参考金属化薄膜电容器的结构是一个可行的思路。但如何使得金属电极满足大应力大形变的需求成为一种柔性电极是一个很大的挑战。碳电极是弹性体中应用最为广泛的电极材料,它拥有极好的形变能力,但对于其自愈性能的深入研究较少且缺乏成熟的理论支撑,使得其在工业领域中难以应用和改善。最后总结对比了金属电极以及碳电极在自愈性能上的差异,并预测了可自愈柔性电极新的发展方向,进一步拓展自愈性的器件在工业领域中的应用。

多层结构聚合物基复合电介质材料储能特性研究进展

聚合物电介质材料由于其成本低、击穿强度高、可靠性高等优点被广泛用于电力系统。但是聚合物电介质材料放电能量密度较低,难以满足新一代小型化电容器的需求,多层结构具有能够协同提升介电常数和击穿强度的优势,解决聚合物电介质介电常数与击穿强度之间的矛盾问题,实现具有优异储能特性的聚合物基电介质材料。文中综述了近年来多层结构聚合物基复合材料的研究进展,分析了多层结构中的极化与击穿现象,并详细讨论了聚合物基多层结构和无机层与聚合物基层结合的多层结构设计,归纳了一些能够提升多层结构聚合物基复合材料储能的方法。例如通过增加界面、优化多层结构中的填料分布以及构建过渡层的方法来提升储能特性。最后,对近年来多层结构聚合物基复合材料的进展进行了总结,并提出了未来的发展方向以及需要解决的关键问题。

PA-Cap在滤波电路中的应用研究

以微机开关电源的滤波电路(工作频率为64.5kHz)来研究PA-Cap(片式聚合物铝固体电容器)在实际电路中的应用情况。实验发现用实测容量28.6μF的PA-Cap代替实测容量为960μF的液体铝电解电容器,可以得到同样的滤波效果;甚至可以用60μF的PA-Cap代替原电路中的960μF的电容和350μH的电感也得到同样的滤波效果。如果用片式二氧化锰钽电解电容,则分别需要127μF和192μF。其主要原因是采用高电导率的聚合物作阴极的PA-Cap具有优异的阻抗频率特性。

导电性高分子混合型铝电解电容器研究

以导电性高分子混合型铝电解电容器为研究对象,研究了电解纸的耐高温特性,优选了阴极箔及研究对耐高温回流焊及寿命试验的影响,研究了添加前处理剂对产品耐高温回流焊能力的影响,对生产工艺进行了优化,研制了耐高温、低阻抗,漏电流小的导电性高分子混合型铝电解电容器。结果表明,所制电容器寿命达到4 000 h(125℃),回流焊后漏电流满足0.01CU规格值。

Ternary polymer nanocomposites with concurrently enhanced dielectric constant and breakdown strength for high-temperature electrostatic capacitors

The exploration of high-energy-density electrostatic capacitors capable of operating both efficiently and reliably at elevated temperatures is of great significance in order to meet advanced power electronic applications.The energy density of a capacitor is strongly dependent on dielectric constant and breakdown strength of a dielectric material.Here,we demonstrate a class of solution-processable polymer nanocomposites exhibiting a concurrent improvement in dielectric constant and breakdown strength,which typically show a negative correlation in conventional dielectric materials,along with a reduction in dielectric loss.The excellent performance is enabled by the elegant combination of nanostructured barium titanate and boron nitride fillers with complementary functionalities.The ternary polymer nanocomposite with the optimized filler compositions delivers a discharged energy density of 2.92 J cm^−3 and a Weibull breakdown strength of 547 MV m^−1 at 150℃,which are 83%and 25%,respectively,greater than those of the pristine polymer.The conduction behaviors including interfacial barrier and carrier transport process have been investigated to rationalize the energy storage performance of ternary polymer nanocomposite.This contribution provides a new design paradigm for scalable high-temperature polymer film capacitors.

Flexible lithium metal capacitors enabled by an in situ prepared gel polymer electrolyte

The rapid development of next-generation flexible electronics stimulates the growing demand for flexible and wearable power sources with high energy density.Li metal capacitor(LMC),combining with a Li metal anode and an activated carbon cathode,exhibits extremely high energy density and high power density due to the unique energy storage mechanism,thus showing great potential for powering wearable electronic devices.Herein,a flexible LMC based on an in situ prepared PETEA-based gel polymer electrolyte(GPE)was reported for the first time.Owing to the high ionic conductivity of PETEA-based GPE(5.75×10^(−3)S/cm at 20℃),the assembled flexible LMC delivers a high capacitance of 210 F/g at 0.1 A/g within the voltage range from 1.5 V to 4.3 V vs.Li/Li^(+),a high energy density of 474 Wh/kg at 0.1 A/g and a high power density of 29 kW/kg at 10 A/g.More importantly,PETEA-based GPE endows the LMC with excellent flexibility and safety,which could work normally under abuse tests,such as bending,nail penetration and cutting.The in situ prepared PETEA-based GPE simplifies the fabrication process,avoids the risk of leakage and inhibits the growth of Li dendrite,making LMC a promising flexible energy storage device for the flexible electronic field.

PA-Cap聚合物电容器在模拟CPU电源中的应用

在计算机CPU的电源电路中,采用电解电容器作为电源的去耦电容。研究了CPU的负载高速变化时,三种类型电容器提供瞬时电流以稳定电源电压的情况。结果显示:PA-Cap聚合物片式叠层铝电解电容器(56μF)的Res为23mΩ,△V为–90mV,而220μF钽电容Res为73mΩ,△V为–172mV,1000μF液体铝电解电容Res为56mΩ,△V为–232mV。因此,PA-Cap聚合物电容器用在开关电源和数字电路中应用前景广阔。

基于击穿增强的全有机复合薄膜储能提升策略研究进展

聚合物薄膜电容器是支撑新能源智能配网发展的重要电力设备之一,提升聚合物电介质薄膜的储能密度是改善薄膜电容器储能器件性能的关键。由经典电磁理论可知,提高聚合物电介质薄膜的储能密度可以从介电常数和击穿强度两个角度实现。然而,目前储能薄膜领域中的综述大多是围绕提高介电常数来增加储能密度的角度进行归纳、分析,而从击穿强度的角度来系统综述的相对较少。因此,文章尝试以全有机聚合物电介质为研究对象,立足于提升击穿强度的角度,重点讨论掺杂、共混、共聚和多层结构的策略。在此基础上,文章还进一步整理和比较各策略的效果,希望为后续在全有机聚合物复合薄膜的结构设计与击穿性能提升方面上提供一些思路。

环烯烃材料应用于电容膜的研究进展

介绍了环烯烃材料的生产机制、工艺及主要性能特点,综述了环烯烃材料在电容器用薄膜领域的研究进展。指出环烯烃共聚物(COC)材料与聚丙烯共混改性成本适中,技术实施难度较小,是耐高温电容膜的开发方向。

高储能密度聚合物基多层复合电介质的研究进展

薄膜电容器是现代电力装置与电子设备的核心电子元件,受限于薄膜介质材料的介电常数偏低,当前薄膜电容器难以获得高储能密度(指有效储能密度,即可释放电能密度),从而导致薄膜电容器体积偏大,应用成本过高。将具有高击穿场强的聚合物与高介电常数的纳米陶瓷颗粒复合,制备聚合物/陶瓷复合电介质,是实现薄膜电容器高储能密度的有效策略。对于单层结构的0-3型聚合物/陶瓷复合电介质,其介电常数与击穿场强难以同时获得有效提升,限制了储能密度的进一步提高。为了解决此矛盾,研究者们叠加组合高介电常数的复合膜与高击穿场强的复合膜,制备了2-2型多层复合电介质,能够协同调控极化强度与击穿场强来获取高储能密度。研究表明,调控多层复合电介质的介观结构与微观结构,可以实现优化电场分布、协同调控介电常数与击穿场强等目标。本文综述了近年来包括陶瓷/聚合物和全有机聚合物在内的多层聚合物基复合电介质的研究进展,重点阐述了多层结构调控策略对储能性能的提升作用,总结了聚合物基多层复合电介质的储能性能增强机制,并讨论了当前多层复合电介质面临的挑战和发展方向。

基于二维多孔有机聚合物制备二维功能化富炭材料的普适性策略及双炭锂离子电容器应用

二维炭材料引起了研究人员广泛的关注,然而,其复杂的合成方法、非均匀的结构以及难以精确控制的性质限制了这一形貌控制科学的发展。本研究开发了一种普适性的制备方法,通过简便的化学交联反应,利用吡咯和吲哚作为氮源,3,4-乙烯二氧噻吩作为硫源,制备了一系列杂原子掺杂的二维多孔聚合物。这种自下而上的策略能够实现高杂原子含量、丰富孔性结构和超薄厚度的功能化炭纳米片的大规模合成。因此,所得到的氮掺杂炭纳米片作为锂离子电容器负极,在5 A g^(-1)条件下表现出573.4 mAh g^(-1)的比容量,而经优化的氮掺杂炭纳米片作为锂离子电容器正极,在5 A g^(-1)条件下表现出100.0 F g^(-1)的比电容。基于此,开发了一种双碳离子电容器,在400 W kg^(-1)条件下,168.4 Wh kg^(-1)的能量密度,循环10000次后循环稳定性保持在86.3%。值得注意的是,这种自下而上的策略为大规模精确定制具有目标结构和性质的二维功能化炭纳米片开辟了新途径。

导电聚合物钽电容器浪涌稳定性研究

导电聚合物钽电容器(PTCs)具有高体积效率、高可靠性、高稳定性、较宽的温度范围和良好的高频特性等特点,是高可靠功率电子电路中不可替代的关键电子元件。新一代电子电路的高电压、大电流和高频率作用于具有异常瞬变电流(ACC)特性的PTCs,导致PTCs的浪涌失效几率增大,失效模式复杂。通过研究分析PTCs中漏电流的成因,影响浪涌失效的主要是位移电流和直流漏电流。采用聚合前、后处理技术,电介质-聚合物界面粘结强度增强,表面缺陷被屏蔽,电介质劣化引起的ACC和漏电流得到遏制。通过500000μF的储能电容器施加浪涌电流和1.5倍额定电压浪涌测试,PTCs漏电流的稳定性得到显著提高,耐受浪涌冲击的能力增强。该研究成果对电子装备系统的安全运行提供有力支撑。

聚合物基电介质薄膜电容器研究进展

简述了聚合物基电介质薄膜电容器的研究现状,主要包括聚丙烯(PP)、聚酰亚胺(PI)以及聚偏二氟乙烯(PVDF)三大类。分析了PP,PI,PVDF三类电介质的介电及理化性质,比较了不同改性手段、加工方式、结构设计等对PP,PI,PVDF电介质电性能的提高程度。对聚合物基电介质薄膜电容器的进一步发展进行了展望。

BMIMPF_(6)/PVDF-HFP/DEC/EC复合GPE制备及性能研究

采用溶胶-凝胶法,选用聚(偏氟乙烯-共六氟丙烯)(PVDF-HFP)作为基底材料,离子液体1-丁基-3-甲基咪唑六氟磷酸盐(BMIMPF_(6))作为导电介质,碳酸二乙酯(DEC)和碳酸乙烯酯(EC)作为增塑剂.成功制备了一种BMIMPF_(6)/PVDF-HFP/DEC/EC复合凝胶聚合物电解质(GPE-BPDE).通过扫描电镜(SEM)、热重分析(TG)以及电化学测试研究了GPE-BPDE材料的结构和电化学性能,结果表明,GPE-BPDE具有良好的热稳定性(分解温度达300℃)、优异的电导率(组装的电容器比电容达187.12 F·g^(-1)).

邻二酮共轭多孔聚合物在电容器中的电化学性能研究

本文以均苯三甲醛、双乙酰作为反应物,吡咯烷作为催化剂,通过羟醛缩合反应在甲醇溶剂中得到邻二酮共轭多孔聚合物。该材料孔径分布范围为2~38 nm,说明其具有介孔结构。由于邻二酮共轭多孔聚合物良好的CV曲线,进一步进行超级电容器与电池性能测试,发现其在酸性条件下超级电容器的比电容可到达20 m F·cm-2。