PE和PP基隔膜性能变化的试验研究

为了提高电池用PE、PP基隔膜实际工作循环中的性能,通过制备PE、PP基隔膜,对其进行SEM表征分析以及力学、电化学试验测试,试验结果表明PE、PP基隔膜的耐腐蚀性均较高,具有较高的安全性,最终得到其力学性能下降的最主要因素为隔膜力学疲劳,隔膜阻抗的大幅增加并未对其内阻产生较大的影响,对我国锂离子电池设计加工具有理论指导意义。     

微量物证技术在锂离子电池隔膜质量鉴定中的应用

为了快速区分锂离子电池隔膜是单层隔膜还是i层隔膜,通过对锂离子电池隔膜进行撕扯实验,观察其在撕扯过程中是否出现中间层,来判断该电池隔膜是单层隔膜还是三层隔膜。经过多次实验发现．单层隔膜在撕扯过程中,不会出现中间层,而三层锂离子电池隔膜,在撕扯到一定长度后就会出现中间层。因此,通过实验可以证明,在锂离子电池隔膜撕扯试验的过程中,出现中间层的电池隔膜可判定为三层隔膜,而实验过程中始终末出现中间层的电池隔膜为单层隔膜。     

PVDF压电薄膜的性能优化研究进展

聚偏氟乙烯(PVDF)压电薄膜是一种压电高分子材料,具有广泛的科学价值和技术应用前景。PVDF薄膜因具有独特的压电效应,且质地软,灵敏度高及频响范围宽等优点,使其在能量收集、新型智能传感器、生物医学、电池隔膜等领域得到了广泛的应用和关注。PVDF晶区中至少有4种晶型,其中β晶型PVDF具有优异的压电性能。该文总结了近年来通过制备工艺、化学掺杂及改性方法的优化来提高β晶型含量,进而提升薄膜性能的方法,系统地介绍了PVDF压电薄膜在部分领域的应用,并对其未来发展做出了展望。     

原纤化PBO纤维耐高温复合隔膜的制备

隔膜对锂离子电池安全性能有着重要影响。为了提高隔膜的耐热性能,采用湿法成型技术,使用聚对苯撑苯并二噁唑(PBO)原纤化纤维和聚对苯二甲酸乙二醇酯(PET)无纺布作为原料,制备了一种耐高温的双层复合隔膜(PET/PBO)。差示扫描量热法(DSC)和热尺寸收缩实验证明,PET/PBO复合膜与商用PP隔膜Celgard 2500相比具有更出色的热稳定性,225℃下尺寸收缩仅2.5%;湿法成型工艺又赋予隔膜更高的孔隙率,可达70%;PBO面与电解液接触角仅为14°,具有良好的电解液浸润性;充放电实验证明,PET/PBO隔膜组装的电池有着良好的循坏和倍率性能。表明该复合膜是高性能锂离子电池隔膜的理想候选者。     

“383Windows”电解质自支撑新构型固体氧化物燃料电池的设计与制备

固体氧化物燃料电池的主要构型有电解质自支撑型与电极支撑型两种,然而这两种构型都存在明显的缺点。前者需要电解质层较厚,导致电池的欧姆阻抗较高,输出功率较低;后者的氧化还原稳定性较差,容易开裂、损坏,导致电池单体开路电压下降甚至完全失效。以氧化钇稳定的氧化锆电解质材料为例成功制备了“383Windows”构型电解质自支撑固体氧化物燃料电池,电解质层间结合紧密,结构稳定,具有优异的力学性能,在保证机械强度的前提下将电解质功能层的厚度成功降低到100μm以下。与同等厚度的厚膜电池相比,在800℃时“383Windows”构型电池的总欧姆阻抗降低了46.7%,输出性能得到了大幅度提高(最大功率密度提升了63.4%)。该结构易于拓展应用到其他电解质体系中制备固体氧化物燃料电池、固体氧化物电解池及全固态锂离子动力电池等,具有很好的商业化前景。     

电源基础

0616928电催化苯加氢反应中气体扩散电极性能的影响因素分析〔刊,中〕/王晶//中国石油大学学报(自然科学版).—2006,30(2).—115-119(E)0616929溶剂、非溶剂对干法制备聚合物隔膜的影响〔刊,中〕/白莹//电源技术.—2006,30(2).—108-111(D)采用相转化法(干法)制备了聚合物锂离子蓄电池用隔膜。通过扫描电镜对隔膜形貌进行分析,研究了在干法制膜过程中溶剂和非溶剂对隔膜形貌和性质的影响。采用交流阻抗技术测定了隔膜的电导率;以丙酮制作溶剂、水为非溶剂制备的隔膜具有良好的电化能,吸液率高达375%。用其装配电池,首次充放电效率88.3%,第…     

不同隔膜对快充型三元锂离子电池性能的影响

隔膜是锂离子电池的重要组成部分,对其性能起着重要影响。通过研究聚对苯二甲酸乙二酯(PET)、纤维素、芳纶、聚丙烯(PP)和聚丙烯/聚乙烯/聚丙烯(PP/PE/PP)隔膜对锂镍钴锰酸锂(NCM)为正极,石墨为负极的快充型锂离子电池性能的影响。结果表明,采用纤维素隔膜的锂离子电池的综合性能最好,10C的高倍率下容量为144 mAh·g~(-1),容量保持率高达95.6%,5C倍率循环500次后的容量没有衰减。采用PET和PP隔膜电池性能也较理想。而采用PP/PE/PP隔膜电池在高倍率下容量快速衰减。由于其低的透气度和内阻以及高的电解液浸润性和吸液率,纤维素隔膜显著提升了三元锂离子电池的倍率性能和循环寿命。     

基于ANSYS的锂离子电池温度场仿真分析

锂离子电池是目前使用最广泛的车用动力电池,本文对SONY-18650圆柱形锂离子电池进行研究,测量了正负极材料和隔膜的导热系数,建立锂离子电池的三维模型,采用ANSYS-Workbench有限元软件进行分析,模拟在不同倍率下的电池温度场分布。结果表明,锂离子电池在不同的放电倍率下,电池温度分布规律基本相同,放电倍率越大,电池温升越高。在低放电倍率下温度对电池材料导热系数的影响可忽略,但是在高放电倍率下,影响较大,不可忽略。     

锂离子电池的安全性能评价技术

锂离子电池是一种更高效、更环保的储蓄电源设备,随着现代科技技术不断的发展,锂离子电池深受人们的喜爱,并将其广泛应用到各种电子产品中。但是,锂离子电池在使用过程中一些细小的结构缺陷会存在着一些安全隐患,对使用者的人身健康造成了一定的威胁,同时我国在锂离子电池检测过程中其技术也落后于锂离子电池技术的发展。因此,为了锂离子电池的安全性能问题,本文对锂离子电池的安全性能评价技术进行了简单的分析。     

国内电动车用动力锂离子电池现状

锂离子电池具有比能量高、比功率大、使用寿命长(循环性能)、工作范围宽等特点,已经应用于纯电动汽车和混合动力汽车中。总结了国内电动车用动力锂离子电池的标准,以及电池结构、正极材料、负极材料、电解液、隔膜、电池管理系统等方面的研究现状,并对国内电动车用动力锂离子电池产业化现状和面临的技术难题进行了阐述。     

Reversible Switching of Battery Internal Resistance Using Iongate Separators

Battery separators are a critical component that greatly determine cell calendar life and safety. Generally, these separators are passive with no ability to reversibly change their properties in order to optimize battery performance. Here, an iongate separator is demonstrated, which allows ion transport while in the oxidized “on” state but limits ion transport when switched to the reduced “off” state. This is achieved by depositing a dense 300 nm thin film of polypyrrole:polydopamine (PPy:PDA) on a conventional polyolefin separator. By using this iongate separator as a third electrode, a rapid and reversible order of magnitude increase of iongate resistance is achievable. The iongate battery shows similar cycling performance to a normal battery while in the “on” state, but cycling can be reversibly shut-off when the iongate separator is reduced to the “off” state. During elevated temperature storage with the iongate separator in the “off” state, battery capacity loss is decreased by 37% and transition metal crossover is greatly suppressed when compared to a normal battery without the iongate. Additionally, rapid shut-off during discharge is demonstrated by directly shorting the iongate separator to the anode.     

Polyoxometalate Modified Separator for Performance Enhancement of Magnesium–Sulfur Batteries

The magnesium–sulfur (Mg-S) battery has attracted considerable attention as a candidate of post-lithium battery systems owing to its high volumetric energy density, safety, and cost effectiveness. However, the known shuttle effect of the soluble polysulfides during charge and discharge leads to a rapid capacity fade and hinders the realization of sulfur-based battery technology. Along with the approaches for cathode design and electrolyte formulation, functionalization of separators can be employed to suppress the polysulfide shuttle. In this study, a glass fiber separator coated with decavanadate-based polyoxometalate (POM) clusters/carbon composite is fabricated by electrospinning technique and its impacts on battery performance and suppression of polysulfide shuttling are investigated. Mg–S batteries with such coated separators and non-corrosive Mg[B(hfip)₄]₂ electrolyte show significantly enhanced reversible capacity and cycling stability. Functional modification of separator provides a promising approach for improving metal–sulfur batteries.     

Composite Separators for Robust High Rate Lithium Ion Batteries

Lithium ion batteries (LIBs) are one of the most potential energy storage devices among various rechargeable batteries due to their high energy/power density, long cycle life, and low self-discharge properties. However, current LIBs fail to meet the ever-increasing safety and fast charge/discharge demands. As one of the main components in LIBs, separator is of paramount importance for safety and rate performance of LIBs. Among the various separators, composite separators have been widely investigated for improving their thermal stability, mechanical strength, electrolyte uptake, and ionic conductivity. Herein, the challenges and limitations of commercial separators for LIBs are reviewed, and a systematic overview of the state-of-the-art research progress in composite separators is provided for safe and high rate LIBs. Various combination types of composite separators including blending, layer, core–shell, and grafting types are covered. In addition, models and simulations based on the various types of composite separators are discussed to comprehend the composite mechanism for robust performances. At the end, future directions and perspectives for further advances in composite separators are presented to boost safety and rate capacity of LIBs.     

Fabrication,Applications, and Prospects of Aramid Nanofiber

Aramid nanofibers (ANFs) are of great interest in various applications due to its 1D nanoscale, high aspect ratio, high specific surface area, excellent strength, and modulus as well as impressive chemical and thermal stabilities. It is considered as one of the most promising nano‐sized building blocks with excellent properties and has therefore drawn increasing attention since 2011. However, no review has summarized the research progress and the prospective challenges of ANF. Herein, the methods of ANF fabrication and their relative merits are comprehensively discussed together with the challenges and progress in the deprotonation method for preparing ANF. The fabrication methods and development of ANF‐based advanced materials with different macroscopic morphologies, including the 1D ANF aerogel fiber, 2D ANF film/nanopaper/coating, and 3D ANF gel and particle are also described. Furthermore, the applications of ANF in nanocomposite reinforcement, battery separators, electrical insulation nanopaper, flexible electronics, and adsorption and filtration media are presented. Additionally, the possible challenges and outlooks toward the future development of ANF are highlighted. This review indicates that the ANF and ANF‐based materials mentioned herein will boost the development of next‐generation advanced functional materials.     

Ultra-Stable Zn Anode Enabled by Fiber-Directed Ion Migration Using Mass-Producible Separator

Aqueous zinc-ion battery (AZB) is a promising candidate for next-generation energy storage owing to inherent safety and low cost. However, AZBs are currently plagued by Zn dendrite growth and undesirable side-reactions, leading to poor cycling stability and premature failure. To restrain the uncontrollable Zn growth, a unique separator is developed based on polyacrylonitrile/graphene oxide (abbreviated as PG) composite nanofibers, which contain abundance of zincophilicity functional groups to regulate the migration and distribution of Zn²⁺ ions in the separator. It is demonstrated that the cyano ligands on PG not only facilitate the dehydration of solvated Zn²⁺ ions prior to deposition, but also form fast lanes to enable homogenous scattering of deposition spots. Benefiting from these features, the PG separator offers a high ionic conductivity of 7.69 mS cm^-1 and a transference number of 0.74 for Zn²⁺. The Zn||Zn symmetrical cells with PG separators achieve an ultra-stable cycle life over 13 000 h. Zn||Zn_0.27V₂O₅ full batteries with PG separators retain 71.5% of the original capacity after 2800 cycles at a high current density of 2 A g^-1. This study offers future research directions toward the design of multifunctional separators to overcome the limits of Zn metal anode in AZBs.     

电子封装用高导热金属基复合材料的研究

高导热金属基复合材料具有优异的热物理性能,且密度较低,是非常理想的电子封装材料。但是由于其本身高的脆性和硬度,使得该材料很难通过二次机械加工成所需要的形状,严重制约了该材料的应用。本文总结了本实验室在第三代SiCp/Al电子封装材料以及第四代金刚石/Cu（或Al）电子封装材料的近净成形制备方面所取得的一些突破性成果,并就相关的关键工艺进行了讨论,论文最后对电子封装用高导热金属基复合材料未来的发展做出了展望。     

Regulating Electronic Structure of Fe–N4 Single Atomic Catalyst via Neighboring Sulfur Doping for High Performance Lithium–Sulfur Batteries

Constructing high performance electrocatalysts for lithium polysulfides (LiPSs) adsorption and fast conversion is the effective way to boost practical energy density and cycle life of rechargeable lithium–sulfur (Li–S) batteries, which have been regarded as the most promising next generation high energy density battery but still suffering from LiPSs shuttle effect and slow sulfur redox kinetics. Herein, a single atomic catalyst of Fe–N₄ moiety doping periphery with S (Fe–NSC) is theoretically and experimentally demonstrated to enhance LiPSs adsorption and facilitated sulfur conversion, due to more charge density accumulated around Fe–NSC configuration relative to bare Fe–N₄ moiety. Thereafter, the graphene oxide supported Fe–NSC catalyst (Fe–NSC@GO) is modified to the commercial separator through a simple slurry casting method. Thus, Li–S cells with Fe–NSC@GO modified separators display high discharge capacity and excellent cyclability, showing 1156 mAh g⁻¹ at 1 C rate and a low capacity decay of only 0.022% per cycle over 1000 cycles. Even with a high sulfur loading of 5.1 mg cm⁻², the cell still delivers excellent cycling stability. This work provides a fresh insight into electrocatalyst structural tuning to improve the electrochemical performance of Li–S batteries.     

Janus‐Faced,Dual‐Conductive/Chemically Active Battery Separator Membranes

Battery separators are supposed to be electrical insulators to prevent internal short‐circuit failure between electrodes as well as having porous channels to allow ion transport. Here, as a multifunctional membrane strategy to dispel this stereotypical belief about battery separators, a new class of Janus‐faced, dual (ion/electron)‐conductive/chemically active battery separators (denoted as “Janus separators”) based on a heterolayered nanofiber mat architecture is demonstrated. The Janus separator, which is fabricated through in‐series, concurrent electrospraying/electrospinning processes, consists of an ion‐conductive/metal ion‐chelating support layer (a mat of densely packed, thiol‐functionalized silica particles spatially besieged by polyvinylpyrrolidone/polyacrylonitrile nanofibers) and a dual‐conductive top layer (a thin mat of polyetherimide nanofibers wrapped with multi‐walled carbon nanotubes). The support layer acts as a chemical trap that can capture heavy metal ions dissolved in liquid electrolytes and the top layer serves as an upper current collector for cathodes to boost the redox reaction kinetics. Notably, the unusual porous microstructure of the top layer is theoretically elucidated using molecular dynamics simulation. Benefiting from such material/structural uniqueness, the Janus separator enables significant improvements in fast‐rate charge/discharge reactions (even for high‐mass loading cathodes) and in the high‐temperature cycling performance, which lie far beyond those achievable with conventional polyethylene separators.     

Polyhedral Oligosilsesquioxane‐Modified Boron Nitride Nanotube Based Epoxy Nanocomposites: An Ideal Dielectric Material with High Thermal Conductivity

Dielectric polymer composites with high thermal conductivity are very promising for microelectronic packaging and thermal management application in new energy systems such as solar cells and light emitting diodes (LEDs). However, a well‐known paradox is that conventional composites with high thermal conductivity usually suffer from the high dielectric constant and high dielectric loss, while on the other hand, composite materials with excellent dielectric properties usually possess low thermal conductivity. In this work, an ideal dielectric thermally conductive epoxy nanocomposite is successfully fabricated using polyhedral oligosilsesquioxane (POSS) functionalized boron nitride nanotubes (BNNTs) as fillers. The nanocomposites with 30 wt% fraction of POSS modified BNNTs exhibit much lower dielectric constant, dielectric loss tangent, and coefficient of thermal expansion in comparison with the pure epoxy resin. As an example, below 100 Hz, the dielectric loss of the nanocomposites with 20 and 30 wt% BNNTs is reduced by one order of magnitude in comparison with the pure epoxy resin. Moreover, the nanocomposites show a dramatic thermal conductivity enhancement of 1360% in comparison with the pristine epoxy resin at a BNNT loading fraction of 30 wt%. The merits of the designed composites are suggested to originate from the excellent intrinsic properties of embedded BNNTs, effective surface modification by POSS molecules, and carefully developed composite preparation methods.     

Pivotal Role of Organic Materials in Aqueous Zinc-Based Batteries: Regulating Cathode,Anode, Electrolyte,and Separator

Aqueous zinc-based batteries have garnered considerable interest as promising energy storage devices due to the low cost, remarkable energy density, high safety, and eco-friendliness. However, the mutual challenges of cathode dissolution, electrolyte parasitic reactions, disordered zinc dendrite growth, and easily punctured separator have significantly impeded the widespread commercialization of aqueous zinc-based batteries. Realizing high-performance zinc-based batteries becomes imperative yet remains extremely challenging. To address these concerns, great efforts have recently been made to design high-performance zinc-based batteries. Here the state-of-the-art in organic materials is critically reviewed for aqueous zinc-based batteries, covering main components of a battery. This review provides a comprehensive overview on the design strategies of organic materials for zinc-based batteries, encompassing cathode, anode, electrolyte, and separator. Furthermore, the challenges and prospective research directions are also discussed to provide a guideline for further development of highly stable zinc-based batteries.