氟化锂及氮化亚铜人工固态电解质膜对锂离子电池正极三元材料的改性

在锂离子电池充放电过程中,电解液与电极材料发生反应,形成的固态电解质膜(solid electrolyte interphase,SEI)随着充放电次数的增加而变厚,这将降低电池的循环稳定性。所制备的人工固态电解质膜(a-SEI)可改善锂离子电池的循环稳定性,其主要成分为使用液相法制备的氟化锂(LiF)、氮化亚铜(Cu 3N)纳米颗粒。通过两种不同路径,将两种纳米颗粒先后在锂离子电池正极三元材料LiNi 0.8 Co 0.1 Mn 0.1 O 2(NCM811)电极片表面和活性材料颗粒表面涂覆生成一层a-SEI。使用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、电化学阻抗谱(EIS)等材料表征和电化学分析方法,解析a-SEI对锂离子电池循环稳定性的影响。结果表明,NCM811材料表面包覆Cu 3N作为a-SEI的电化学性能最好,相比纯NCM811材料,50周循环后的容量保持率可提升26.5%。     

Electrode/electrolyte interface and interface reactions of solid oxide cells:Recent development and advances

High temperature solid oxide cells(SOCs) consisted of solid oxide fuel cells(SOFCs) and solid oxide electrolysis cells(SOECs) are considered one of the most environmentally friendly and efficient energy conversion technology to store renewal energy from sun and wind in hydrogen and generate electricity from the fuels such as hydrogen and natural gas with high efficiency and very low greenhouse gas emission. Over the last few decades, the development of SOC technologies in particularly SOFCs has experienced significant progress and much of the recent research have paid great efforts in understanding the processes occurring at the electrode/electrolyte interfaces. As electrochemical reactions mainly proceed at the gas, electrode and electrolyte three phase boundaries(TPBs), the microstructure and properties of the electrode/electrolyte interfaces thus play a crucial role in determining the overall cell performance and durability. Herein, we review the progress and achievements in the fundamental researches of the electrode/electrolyte(mainly oxygen-conducting) interface evolution behavior under open circuit and polarization conditions. Studies involving interfacial phenomena such as interface formation and reactions, element segregation and diffusion, micropore formation and delamination are summarized and discussed in detail. Besides, the state of the art characterization techniques that have been employed to examine the interface behavior are reviewed. Finally, the challenges and prospects of the interface research in the improvement of the performance and durability of a SOC device are discussed.     

改性剂对PVA基碱性固体聚合物电解质性能的影响

为了改善PVA-KOH-H2O体系碱性固体聚合物电解质(ASPE)的性能,采用溶液浇铸法向其中添加改性剂制备复合电解质膜,利用X射线衍射仪(XRD)、循环伏安法(CV)和交流阻抗法(AC)等对电解质膜的物相和性能进行了表征.研究结果表明:聚合物电解质以无定形态为主,含极少量晶相,改性剂的适量添加可以降低电解质膜的结晶度增大无定形区域,离子电导率随PEO的加入先减小后增大,随增塑剂的加入先增大后减小,三种改性剂中GROL效果最好可达4.52×10-2 S/cm,电化学稳定窗口随改性剂的添加略微变窄,但仍显示了较好的电化学稳定性,当三种物质同时共混加入时电化学性能优于单个组分.该研究结论对制备高能量碱性固体电池具有一定的参考价值.     

三维聚合物电解质膜燃料电池中水的输运模拟

针对新型螺旋形加压聚合物电解质膜燃料电池,提出了一种液态水生成和输运效应的数值模型.该数值模型基于燃料电池的物理机理、流体流动、传热导、多孔介质中的传质、电化学反应、含相变的多相流动、电流输运、多孔介质和固体导电区域中的位势场以及穿过聚合物膜的水的输运设计优化过程.在分析中还使用了燃料电池模型.例如,电化学模型--用于预测局部电流密度和电压分布;位势场模型--用于预测多孔介质以及固体导电区中的电流和电压;多相混合物模型--用于预测在多孔扩散层中的液态水和气体流;薄膜多相模型--用于研究气体流道中的液态水流.最后给出了聚合物电解质膜燃料电池液态水生成和输运的理论模型的数值结果,包括催化层和膜中的H2,O2和H2O的质量和克分子数的等值线图.     

中低温固体氧化物燃料电池电解质材料研究进展

 固体氧化物燃料电池（SOFC）是一种全固态的电化学能量转换装置,它的能量转换效率高达70%,且其尾气中的有毒成分含量极低,是未来化石燃料发电技术的理想选择之一。SOFC 具有较宽的工作温度范围,通常在450~1000℃。高温下（800~1000℃）尽管SOFC 在燃料选择方面具有更高的灵活性,但是材料性能衰减的加快、运营成本的提高,以及系统的开关速度变慢等一系列缺点也愈加明显。因而,SOFC 主要朝着低温化的趋势发展。降低SOFC 工作温度最有效的方法是提高固体电解质的电导率,以尽量减少电池的欧姆阻抗。本文综述了萤石型、钙钛矿型和复合型3 类固体电解质材料国内外的研究进展,同时展望了未来中低温SOFC 电解质材料的研究方向。钙钛矿型电解质材料在中低温下具有较高的纯离子电导率,且具备丰富的改性空间,有望成为将来中低温SOFC 电解质材料的首选。     

电化学电容器过渡金属氧化物电极材料的制备方法

综述了近年来电化学过渡金属氧化物电极材料电容器制备方法、讨论了这些方法的优缺点.通过对这些方法的比较,指出溶胶凝胶法最适合制备具有准电容特征的电化学电容器金属氧化物电极材料.     

固体氧化物电解质膜反应器在非均相催化中的应用

固体氧化物电解池用作膜反应器，可以共生电能和化学产品，通过固体电解质电势分析法与动力学测量相结合可进行非均相催化反应机理研究；该膜反应器还可用于催化剂活性的电化学改性研究，本文主要从以上3个方面对固体氧化物膜反应器在非均相催化方面的应用作了归纳。     

锂离子电池碳负极中边缘碳及表面碳原子含量的理论计算

通过理论分析与计算得到边缘碳及表面碳原子含量的表达式。分析了石墨微晶结构与成键特征,研究了石墨微晶中边缘碳原子与基平面碳原子的电化学特性。结果表明:边缘碳原子比基平面碳原子更易于与其他原子或基团形成较为稳固的联接,电化学反应活性较高;在首次充电过程中,边缘碳原子附近电解质的分解与SEI膜成膜反应速度较快,有利于形成联接较为紧密的SEI膜;建立了紧密堆砌的正六棱柱颗粒模型,推导出理想石墨中边缘碳原子及表面碳原子含量与微晶参数、颗粒尺寸之间的关系式。通过引入适当因子,修正了实际石墨颗粒与理想石墨在结构、形貌、孔隙率等方面的差别,得到的表达式可适用于石墨、无定形碳及改性碳等多种碳材料碳原子含量的计算。     

高性能复合固态电解质的制备及固态锂金属电池性能研究

固态锂金属电池相较于传统液态电池,其能量密度更高、安全性更好,具有巨大的应用前景。但聚合物固态电解质离子电导率低、强度低、电化学稳定性差,阻碍了其进一步发展。将丁二腈与聚碳酸丙烯酯通过无溶剂法加以玻璃纤维作为支撑制备了室温下高性能的复合固态电解质。所制备的复合固态电解质在室温下离子电导率达3.06×10^?4 S/cm,锂离子迁移数达0.47,电化学窗口最高达4.3 V;其锂金属对称电池在电流为0.1 mA/cm²的条件下,稳定循环超400 h;磷酸铁锂固态锂金属电池0.5 C循环100次的容量保持率为95.9%,展现出良好的循环稳定性。     

Chevrel phase: A review of its crystal structure and electrochemical properties

Chevrel phase compounds have attracted increasing attention as electrochemical energy storage materials and electro-catalysts. Benefiting from their unique crystal structure, Chevrel phase compounds can not only function as the host structures for reversible intercalation of a broad range of cations, but also exhibit high catalytic activity in electrochemical reduction reactions. Here we provide an overview of recent progress in the development of Chevrel phase materials including new understand...     

Safety characteristics of Li-ion batteries evaluated by in situ measurement techniques

Li-ion batteries hold an important place in the field of high power batteries because of their high open circuit voltage and associated high energy density. However, the safety is less satisfactory; therefore, the study of the factors that affect the safety of Li-ion batteries has much meaning to the safety design. In this paper, a set of apparatus was developed for in situ measurements, and several commercial materials including electrolyte, separator and electrode materials for Li-ion batteries were investigated by the in situ method. The results showed： 1） The electrolyte vapor pressure is influenced significantly by the component with low boiling point and increases rapidly with the increasing of temperature; 2） the shutdown of separator occurs at around 135℃ and the impedance increases approximately by two orders of magnitude; 3） carbon anode materials affect the most the volume changes of the cell, and the change for a graphite anode is much greater than that of a glassy carbon anode.     

旋风除尘器的气固两相流的数值模拟与分析

采用Reynold应力方程湍流模型(RSM)模拟了旋风除尘器内的流场,并得到流场内Reynold应力具有各向异性的特征.采用离散相模型(DPM),模拟了固体颗粒运动轨迹,并对固体颗粒的分离效率进行了分析.     

改性PVDF-HFP基凝胶电解质的合成及锂金属电池性能研究

开发高质量的固态电解质,对制造新一代安全稳定的固态锂金属电池具有重要意义。以聚偏氟乙烯–六氟丙烯(polyvinylidene fluoride-hexafluoropropylene, PVDF-HFP)为聚合物基体,引入MOF-808作为活性填料,采用溶液浇筑法制备了新型凝胶聚合物电解质。优化后的凝胶聚合物电解质在室温下的离子电导率高达3.21 mS/cm,电化学稳定窗口可达5.0 V、具有较高的Li^＋迁移数(0.63)、与锂金属具有良好的界面相容性。组装的磷酸铁锂全电池在0.5 C倍率下循环250次,容量保持率为86.7%。高性能凝胶聚合物电解质对提升锂金属电池的循环稳定性与安全性具有重要的应用价值。     

Practical development and challenges of garnet-structured Li7La3Zr2O12 electrolytes for all-solid-state lithium-ion batteries: A review

All-solid-state Li-ion batteries (ASSLIBs) have been widely studied to achieve Li-ion batteries (LIBs) with high safety and energy density. Recent reviews and experimental papers have focused on methods that improve the ionic conductivity, stabilize the electrochemical performance, and enhance the electrolyte/electrode interfacial compatibility of several solid-state electrolytes (SSEs), including oxides, sulf-ides, composite and gel electrolytes, and so on. Garnet-structured Li7La3Zr2O12 (LLZO) is highly regarded an SSE with excellent application potential. However, this type of electrolyte also possesses a number of disadvantages, such as low ionic conductivity, unstable cubic phase, and poor interfacial compatibility with anodes/cathodes. The benefits of LLZO have urged many researchers to explore effective solutions to over-come its inherent limitations. Herein, we review recent developments on garnet-structured LLZO and provide comprehensive insights to guide the development of garnet-structured LLZO-type electrolytes. We not only systematically and comprehensively discuss the preparation, ele-ment doping, structure, stability, and interfacial improvement of LLZOs but also provide future perspectives for these materials. This review expands the current understanding on advanced solid garnet electrolytes and provides meaningful guidance for the commercialization of ASSLIBs.     

Preparation and characterization of a novel composite microporous polymer electrolyte for Li-ion batteries

A novel composite microporous polymer electrolyte composed of poly（vinylidene fluoride-co-hexafluoropropylene） （PVdF-HFP） and mesoporous SBA-15 was prepared. The composite solid polymer electrolyte （CSPE） exhibits ionic conductivity as high as 0.30 mS·cm^-1 with a composition of SBA-15 ： PVdF-HFP=3 ： 8 at room temperature. Infrared transmission spectroscopic results suggested that the mechanism of micropore formation is similar to that of the phase inversion. X-ray diffraction （XRD） results demonstrated that the addition of SBA-15 inhibits the crystallization of PVdF-HFP, while the SBA-15 preserves well its ordered mesoporous structure during the course of preparation. The Li/CSPE/MCF of half-cell was assembled, and it showed a good electrochemical and cyclability performance during charge-discharge cycles.     

气固催化反应流动的CFD-DEM模拟研究

针对复杂气固催化反应流动系统,提出一种新的气固催化反应流动的模型框架,即CFD-DEM反应流模型框架,计算流体力学（CFD）方程用于描述气相的流动和传递行为,离散单元法（DEM）用于描述颗粒相的运动。结合石油催化裂化（FCC）过程,考虑颗粒间传热和气固相间传热模型、催化剂颗粒瞬态失活模型以及FCC过程的4集总动力学模型,建立完整的CFD-DEM反应流模型。应用所建模型模拟在不同剂油比操作下高2m,宽0.05m的二维提升管和下行式反应器内的FCC过程。由于能实时追踪各个催化剂颗粒的运动、传热和化学反应行为,模拟结果直接揭示了不同的流动结构和颗粒返混行为对反应器性能（如汽油、焦炭等产物的选择性）的影响。此外,方法论本身可推广至FCC过程以外的气固相催化或非催化过程的精细描述。     

超浸润纳米阵列电极用于气体参与电催化反应的研究进展

气体参与的电催化反应，包括气体析出反应和气体消耗反应，是能量转换过程和化工过程中的重要环节。相比于针对高活性催化剂的研究，对于实际的工业生产过程，调控反应过程中的气体扩散行为对高电流的工业应用有着同样重要的意义。虽然目前已经有不少纳米阵列电极用于有气体参与的电催化反应实例，且表现出较好的电化学性能，但对于气泡在电极材料表面的浸润性行为的基础研究却较少。本文旨在系统地介绍结构化的超浸润纳米阵列电极在气体参与的电催化反应中的作用及应用，从介绍超疏气性和超亲气性定义出发，提出优化电极结构、制备超疏气性和超亲气性电极的方法，然后介绍了几种电极材料在能量转换系统中的应用，最后讨论了超浸润电极未来的发展前景。     

基于SPH方法连续液滴撞击固壁面模拟

 为了研究连续液滴对固壁面的撞击影响, 引入一种纯Lagrange、无网格计算方法, 即光滑粒子流体动力学方法(SPH)。对连续液滴撞击固壁面的扩散、回弹及飞溅进行了数值模拟并与实验测试进行比对。结果表明:连续液滴撞击固壁面时, 液滴的自由表面变化具有许多不确定性, 其中次生液滴的产生和韦伯数的作用是影响液滴撞击扩散的主因。次生液滴的出现使得液滴扩散及飞溅变得更为明显, 韦伯数越大, 连续液滴的无量纲直径变化越快。模拟效果真实反映了液滴撞击过程, 可为类似撞击问题的仿真分析提供借鉴。     

Effects of environmental factors on corrosion behaviors of metal-fiber porous components in a simulated direct methanol fuel cell environment

To enable the use of metallic components in direct methanol fuel cells (DMFCs), issues related to corrosion resistance must be considered because of an acid environment induced by the solid electrolyte. In this study, we report the electrochemical behaviors of metal-fiber-based porous sintered components in a simulated corrosive environment of DMFCs. Three materials were evaluated: pure copper, AISI304, and AISI316L. The environmental factors and related mechanisms affecting the corrosion behaviors were analyzed. The results demonstrated that AISI316L exhibits the best performance. A higher SO₄2- concentration increases the risk of material corrosion, whereas an increase in methanol concentration inhibits corrosion. The morphological features of the corroded samples were also characterized in this study.     

基于长程力的SPH方法固壁边界处理

将近场动力学(PD)中的长程力引入光滑粒子流体动力学(SPH)的固壁边界处理模型中,给出一种适合SPH方法边界处理的新方法。通过液柱坍塌、Poiseuille流、水铸造充型仿真和土体崩塌4个算例对该方法的有效性进行验证。结果表明:该方法能很好地解决粒子非物理穿透边界;能客观反映真实的边界作用;对于复杂几何边界和具有材料强度的动力学问题也相当有效。