锂离子动力电池电解液的热稳定性

锂离子动力电池是电动飞行器的核心部件,电池能否在飞行中保持正常工作状态直接决定驾乘人员和飞行器的安全,因此研究锂离子动力电池的安全性对于电动飞机和其他清洁能源项目的推广具有十分重要的意义.目前的工作主要针对锂离子动力电池电解液的热稳定性进行实验研究.首先使用TDB-6A型电脑闭口闪点测定仪对6种不同锂离子动力电池电解液进行闪点测定,然后,使用ARSST反应测试系统研究电解液在加热过程中的热失控反应.通过对所得实验数据的分析能够确定这6种锂离子动力电池电解液热稳定性的排序由高到低为:YH-51-7、YH-11-15、YH-61-7、YH-65-6、YH-51-6、YH-51-8.目前的实验结果可以为轻型电动飞机锂离子动力电池安全性研究提供有益的参考.     

有机电解液在锂离子电池中的充放电机理

讨论了锂离子电池充放电过程中有机电解液的电化学行为,研究发现,有机电解液会在电极活性材料表面发生电化学反应而形成聚合物钝化层(SEI膜),其厚度和疏密性与电解液的组成及充放电制度有关;其组成和电化学性能还将直接影响锂离子电池的充放电容量和循环寿命。通过改变电解液的导电锂盐成分、有机溶剂组成和加入极性添加剂等方法可优化电解液的电化学特性,从而可有效控制该钝化层的成膜过程、膜组成与膜结构,提高锂离子电池的充放电及循环性能。     

The function of vinylene carbonate as a thermal additive to electrolyte in lithium batteries

The role of vinylene carbonate (VC) as a thermal additive to electrolytes in lithium ion batteries is studied in two aspects: the protection of liquid electrolyte species and the thermal stability of the solid electrolyte interphase (SEI) formed from VC on graphite electrodes at elevated temperatures. The nuclear magnetic resonance (NMR) spectra indicate that VC can not protect LiPF₆ salt from thermal decomposition. However, the function of VC on SEI can be observed via impedance and electron spectroscopy for chemical analysis (ESCA). These results clearly show VC-induced SEI comprises polymeric species and is sufficiently stable to resist thermal damage. It has been confirmed that VC can suppress the formation of resistive LiF, and thus reduce the interfacial resistance.     

Synthesis of highly Li-ion conductive garnet-type solid ceramic electrolytes by solution-process-derived sintering additives

The sintering and processing of garnet-type solid ceramic electrolytes (e.g., Li₇La₃Zr₂O₁₂ (LLZ)) are challenging because the material composition and microstructure at high temperatures must be carefully controlled to obtain the stabilization of highly conductive cubic phase and dense ceramic. Liquid-phase sintering using sintering aids is typically used for densifying ceramic materials, as it is a faster and/or lower-temperature process. In this study, we used solution-process-derived sintering additives to sinter garnet-type solid electrolytes highly effective in terms of relative density and properties at 1000 °C (10 h). The liquid phase formation during the sintering was rationalized to establish the optimal sintering conditions. The use of 1.2-vol% 75Li₂O∙25B₂O₃ and 1.5-vol% Al₂O₃ as sintering additives was highly effective in densifying a Ta-doped LLZ, achieving a high ionic conductivity of 0.8 mS cm⁻¹ (25 °C) with low activation energy (9 kJ mol⁻¹) and almost negligible contribution of the grain boundary resistance (10 %).     

有机电解液对锂离子电池合金型负极材料性能的影响

锂离子电池合金型负极材料的研究得到了广泛的关注,但是合金电极与电解液相互作用的研究非常少。本文采用电镀和热处理相结合的方法制备出Cu₆Sn₅合金薄膜电极,研究了各种电解液对电极性能的影响。研究结果表明,合金电极在LiN(CF₂SO₂)₂(LITFSI)为溶质的电解液中表现出比在常用的以LiPF₆作为溶质的电解液中更高的容量和更好的循环性能。合金薄膜电极在1mol·L^-1 LITFSI/EC∶DEC(1∶2)电解液中具有更小的反应电阻和更大的反应电流密度,锂离子在电极上插入和脱嵌的可逆性良好,反应电阻只有在1mol·L^-1 LiPF₆/PC电解液中的1/10。研究结果表明,乙烯碳酸酯(EC)由于在充放电过程中会形成固体电解质界面（SEI）膜,能大幅度提高材料的电化学性能,在锂离子电池中是不可或缺的。     

锂离子电池新型电解液的研究进展

电解液作为锂离子电池的关键材料之一,其在正、负极之间起到传递离子的作用。近年来新型电解液的研究备受关注,主要对高电压电解液、超低温电解液、阻燃电解液和聚合物电解质等4方面进行了简要综述。     

固态金属锂电池研究进展：外部压力和内部应力的影响

固态锂金属电池具有理论能量密度高、安全性高等优势,是极有前景的下一代储能系统。然而,固体电极与固体电解质之间有限的固–固接触严重阻碍了界面离子的传输。因此,增加外部压力是增加固–固接触及延长电池循环寿命的重要途径。同时,在充放电过程中,电极体积变化产生的内应力也将影响电池界面特性。通过介绍两种基本物理接触模型,结合硫化物、氧化物、聚合物电解质以及金属锂的物理性质,综述了外压和内部应力对电解质、电极及电池的影响。最后,对外压力与内应力在全固态金属锂电池中的作用进行了总结和展望。     

锂离子电池电解液负极成膜添加剂的研究进展

解决锂离子电池电极材料和电解液相容性的关键是形成稳定且Li⁺可导的固态电解质界面膜(SEI膜),因此,对优质负极成膜添加剂的研究成为锂离子电池研发中的一个热点。本文综述了锂离子电池电解液成膜添加剂的作用原理,具体介绍了各类负极成膜添加剂的研究现状,从成膜反应机理和理论计算方面详述了近几年来负极成膜添加剂的研究进展。分析了所存在的问题主要是如何快速地挑选出更适宜、更高效的成膜添加剂,并指出了成膜添加剂未来的发展趋势为:①研究各添加剂与电解液的反应机理,着重开发对锂离子电池副反应小的负极成膜添加剂;②通过选择两种或两种以上的添加剂的协同作用,以弥补一种添加剂的不足;③提高无机成膜添加剂在电解液中的溶解度。     

全钒液流电池开路电压模型

建立全钒液流电池六参数开路电压计算模型,揭示开路电压由电池总电势和VO₂⁺/VO²⁺电极电势决定,并与电解液中钒离子透膜扩散行为密切相关。模型计算得到开路电压存在两个电压平台和一个转折点,与实验结果较为一致。利用该模型计算了电池开路时电解液中4种钒离子浓度随时间的变化关系,指出电池电解液不均衡性是由不同价态钒离子在膜相的Donnan平衡和透膜扩散系数不同产生的。该模型可为优化电池操作提供理论指导,并可为电池长期运行时电解液管理提供工程指导。     

自制高压电动机的综合继电保护装置

阐述了在工业生产中常大量采用的高压异步电动机在运行中可能发生的故障及由此产生的危害;进而阐明,在只装有3个引出端子的一般高压电动机上配置1套通用的综合继电保护装置,对全面保护电动机的安全运行十分必要。     

铝电解电容器用新型宽温高压工作电解液

采用异癸二酸铵为主溶质,乙二醇和γ-丁内酯为复合溶剂,制备新型宽温(-40~105℃)、高压(400 V)铝电解电容器工作电解液,并检测了该电解液和用该电解液生产的电解电容器的性能。测试结果表明,该工作电解液25℃时电导率达到1.6 mS/cm,闪火电压为480 V,-40℃下未见晶体析出;CD 110/400 V铝电解电容器试样的漏电流≤10μA,损耗0.03,容量变化率只有-3%。经过105℃高温贮存250 h后各项电气性能不仅优于国家标准,而且能达到严格的企业标准。     

高压电路防污闪带电清洗维护技术可行性研究

比较全面地论述了带电清洗中的高压带电清洗剂、高压带电清洗工具、高压带电施工工艺和高压带电安全措施等内容。     

功能硅烷在有机-无机复合固态电解质中的应用研究进展

有机-无机复合固态电解质不仅具有聚合物电解质的柔韧性和界面相容性,还能显著提高离子传导性和力学性能。然而,构建良好的填料/聚合物分散体系是制备此类复合电解质的难点,设计新型有强相互作用的功能化填料以调控界面渗流结构也面临巨大挑战。通过功能硅烷对无机填料进行化学键联改性或原位合成是解决无机填料与聚合物间分散性和界面相容性问题的有效策略。本文综述了在复合固态电解质中利用功能硅烷对无机填料进行表面改性和原位合成、功能硅烷作为复合固态电解质的交联中心和制备离子胶类复合固态电解质四方面的研究进展,重点阐述了硅烷功能化填料与固态电解质结构和性能之间的关系。最后对功能硅烷在有机-无机复合固态电解质中的应用研究进行了总结和展望。     

Open circuit voltage for solid polymer electrolyte/salt systems in lithium batteries

The open circuit voltage (OCV) model of the solid polymer electrolyte (SPE)/salt system in lithium batteries is established by combining concentrated solution theory with the modified double lattice–non-random (MDL-NR) model which describes the non-ideal behavior of the salt activity in the polymer electrolyte. The activity parameters are obtained from the phase diagram for the given systems and used to describe the OCV of the corresponding systems with one additional parameter, transport number, t ₊ ⁰ . The proposed model agrees very well with the OCV data for various PEO/salt systems.     

An ambient-temperature superionic conductive,electrochemically stable,plastic cross-linked polymer electrolyte for lithium metal battery

A plastic cross-linked polymer is prepared using acrylonitrile as a monomer and poly(ethylene glycol diacrylate) as a linking agent. A phase diagram-guide rational design is introduced to fabricate the polymer composite electrolyte in the case of succinonitrile complexed with lithium bis-trifluoromethanesulfonimide. The plastic cross-linked polymer-based electrolyte films with ambient-temperature superionic conductivity (2.33 mS cm⁻¹) and a wide electrochemical window (0–5.6 V vs. Li/Li⁺) have been demonstrated. The charging and discharging experiments of the plastic polymer composite electrolyte-based lithium batteries show that the plastic polymer electrolyte can cycle normally and safely at a current density of 0.5 mA cm⁻². These batteries exhibit excellent average coulombic efficiency of 98.5% in the first 150 cycles. The initial capacity at 25°C is 127.5 mAh g⁻¹ (0.2 C), which is close to the value achieved by liquid-electrolyte-based cells under similar conditions. The capacity retention is 91% after 150 cycles.     

H9110F级无溶剂浸渍树脂在高、低压电机上的应用

本文介绍了H9110不饱和聚酯亚胺无溶剂浸渍树脂的热老化试验、常态电老化试验和热电老化试验,并以其在高压电机少胶VPI绝缘结构和低压散嵌绕组电机上的实际应用为例,提出高、低压电机通用绝缘浸渍树脂的新概念。     

A panoramic view of Li7P3S11 solid electrolytes synthesis,structural aspects and practical challenges for all-solid-state lithium batteries

The development of an inorganic electrochemical stable solid-state electrolyte is essentially responsible for future state-of-the-art all-solid-state lithium batteries (ASSLBs). Because of their advantages in safety, working temperature, high energy density, and packaging, ASSLBs can develop an ideal energy storage system for modern electric vehicles (EVs). A solid electrolyte (SE) model must have an economical synthesis approach, exhibit electrochemical and chemical stability, high ionic conductivity, and low interfacial resistance. Owing to its highest conductivity of 17 mS·cm^-1, and deformability, the sulfide-based Li₇P₃S₁₁ solid electrolyte is a promising contender for the high-performance bulk type of ASSLBs. Herein, we present a current glimpse of the progress of synthetic procedures, structural aspects, and ionic conductivity improvement strategies. Structural elucidation and mechanistic approaches have been extensively discussed by using various characterization techniques. The chemical stability of Li₇P₃S₁₁ could be enhanced via oxide doping, and hard and soft acid/base (HSAB) concepts are also discussed. The issues to be undertaken for designing the ideal solid electrolytes, interfacial challenges, and high energy density have been discoursed. This review aims to provide a bird's eye view of the recent development of Li₇P₃S₁₁-based solid-state electrolyte applications and explore the strategies for designing new solid electrolytes with a target-oriented approach to enhance the efficiency of high energy density all-solid-state lithium batteries.     

Critical analysis of aqueous tape casting,sintering, and characterization of planar Yttria‐Stabilized Zirconia electrolytes for SOFC

Tape casting is an established forming technique for several industries, however, researches focus more on slurry composition. In this work, the combined use of design of experiment and materials characterization techniques showed tape casting process parameters have great influence on the microstructure and mechanical properties of green tapes. Formulation and processing optimization allowed obtaining YSZ green tapes with good mechanical characteristics and homogeneous microstructure without laminating step. The optimized sintering schedule and sintering load allowed obtaining planar electrolytes with high density, tensile strength, and electrical conductivity. This work provides an environmental friendly procedure for large‐scale production of SOFCs planar electrolytes.     

Effect and mechanism analysis of matrix resin type on thermal aging characteristics of semi-conductive shielding material for high voltage cable

The type of matrix resin of the semi-conductive shielding layer directly affects the thermal aging characteristics of the semi-conductive shielding layer and the high-voltage cable. In this paper, ethylene vinyl acetate (EVA), ethylene ethyl acrylate (EEA), and ethylene butyl acrylate (EBA) resins were used as matrix to prepare carbon black (CB) + EVA, CB + EEA, and CB + EBA shielding materials. The law of physicochemical, electrical, and mechanical properties of different matrix resin shielding materials with aging time was studied, and the influence mechanism of matrix resin on the aging characteristics of shielding materials was analyzed. The results show: with the increase of aging time, the crystallization area and the number of functional groups of the three shielding materials decreased to varying degrees. The number of functional groups in CB + EBA shielding materials decreased evenly with aging time, but that of CB + EVA and CB + EEA shielding materials changed significantly after 7 days of aging. After 60 days of aging, the crystallization area of CB + EBA shielding material changed slightly, but that of CB + EVA and CB + EEA shielding material decrease significantly. The electrical properties of the three shielding materials showed different decreasing trend with aging time. When the aging time is 7 days, the positive temperature coefficient (PTC) effect of CB + EEA shielding material decreases obviously. When the aging time is 30 days, the resistivity of CB + EVA and CB + EEA shielding material increases slowly (9 Ω cm–12 Ω cm) with the increase of temperature. When the aging time is 60 days, the resistivity of CB + EBA shielding material decreases obviously, and the PTC effect weakens obviously. Taking the mechanical properties of the shielding material as reference, the rapid deterioration stage of the mechanical properties of the three shielding materials is different. The CB + EVA and CB + EEA shielding material rapid deterioration time is 0–7 days, and the tensile strength and elongation of the shielding material are greatly reduced. The rapid deterioration stage of CB + EBA shielding material is 7–30 days, and the tensile strength and elongation decrease from 24.38 MPa and 499.5% to 14 MPa and 155.7%, respectively. This work can provide data support for the selection of matrix resin of shielding material and the fault analysis of shielding layer of high voltage cable.     

Polymer membranes for high temperature proton exchange membrane fuel cell: Recent advances and challenges

Proton-exchange membrane fuel cells (PEMFCs) are considered to be a promising technology for efficient power generation in the 21st century. Currently, high temperature proton exchange membrane fuel cells (HT-PEMFC) offer several advantages, such as high proton conductivity, low permeability to fuel, low electro-osmotic drag coefficient, good chemical/thermal stability, good mechanical properties and low cost. Owing to the aforementioned features, high temperature proton exchange membrane fuel cells have been utilized more widely compared to low temperature proton exchange membrane fuel cells, which contain certain limitations, such as carbon monoxide poisoning, heat management, water leaching, etc. This review examines the inspiration for HT-PEMFC development, the technological constraints, and recent advances. Various classes of polymers, such as sulfonated hydrocarbon polymers, acid-base polymers and blend polymers, have been analyzed to fulfill the key requirements of high temperature operation of proton exchange membrane fuel cells (PEMFC). The effect of inorganic additives on the performance of HT-PEMFC has been scrutinized. A detailed discussion of the synthesis of polymer, membrane fabrication and physicochemical characterizations is provided. The proton conductivity and cell performance of the polymeric membranes can be improved by high temperature treatment. The mechanical and water retention properties have shown significant improvement., However, there is scope for further research from the perspective of achieving improvements in certain areas, such as optimizing the thermal and chemical stability of the polymer, acid management, and the integral interface between the electrode and membrane.