力曲线用于硅负极材料表面膜的研究

利用原子力显微镜（AFM）力曲线模式来研究锂离子电池硅负极材料在含碳酸亚乙烯酯添加剂（VC）电解质首周循环时固态电解质相表面膜（SEI膜）的三维结构. 测试表明SEI膜具有多层结构,同时得到SEI膜厚度、杨氏模量以及覆盖度在首周循环过程中的变化,采用三维图呈现了硅材料表面膜的分布.     

非水溶剂Li-O2电池锂负极研究进展

The aprotic Li-O₂ battery has attracted considerable interest in recent years because of its high theoretical specific energy that is far greater than that achievable with state-of-the-art Li-ion technologies. To date, most Li-O₂ studies, based on a cell configuration with a Li metal anode, aprotic Li⁺ electrolyte and porous O₂ cathode, have focused on O₂ reactions at the cathode. However, these reactions might be complicated by the use of Li metal anode. This is because both the electrolyte and O₂ (from cathode) can react with the Li metal and some parasitic products could cross over to the cathode and interfere with the O₂ reactions occurring therein. In addition, the possibility of dendrite formation on the Li anode, during its multiple plating/stripping cycles, raises serious safety concerns that impede the realization of practical Li-O₂ cells. Therefore, solutions to these issues are urgently needed to achieve a reversible and safety Li anode. This review summarizes recent advances in this field and strategies for achieving high performance Li anode for use in aprotic Li-O₂ batteries. Topics include alternative counter/reference electrodes, electrolytes and additives, composite protection layers and separators, and advanced experimental techniques for studying the Li anode|electrolyte interface. Future developments in relation to Li anode for aprotic Li-O₂ batteries are also discussed.     

石墨负极电化学扫描循环过程的EIS、Raman光谱和XRD研究

运用电化学阻抗谱(EIS)、Raman光谱和XRD研究了石墨负极在1 mol/L LiPF6-EC∶DEC∶DMC电解液中的电化学循环扫描过程. EIS研究结果表明, 在电化学循环扫描4~10周范围内, SEI膜(固体电解质相界面膜)电阻随循环扫描周数增加近似线性增长, 但石墨负极/电解液界面总阻抗由于电荷传递电阻的降低而减小. Raman光谱研究结果表明, 在经历电化学循环扫描后, 活性材料表层发生粉化和无定形化, 石墨化程度降低; 但XRD研究结果显示, 石墨材料的本体结构没有发生变化, 仍然保持着完整的石墨层状结构.     

锂金属负极的可逆性与沉积形貌的关联

高能量密度二次电池的商业化将会推动便携式电子设备和电动车的飞速发展。锂金属电池因具有较高的理论能量密度而受到研究者的广泛关注。然而,锂金属负极较低的库仑效率(CE)和枝晶生长等问题,严重制约了锂金属电池的发展。库仑效率是衡量电池体系可逆性的关键参数之一,锂金属负极的库仑效率在不同电解液中存在较大的差异,本文以四种常见的电解液为例,包括1 mol·L^-1六氟磷酸锂-碳酸乙烯酯/碳酸二甲酯电解液,1 mol·L^-1六氟磷酸锂-碳酸乙烯酯/碳酸二甲酯+5%(w)氟代碳酸乙烯酯电解液,1 mol·L^-1双(三氟甲烷磺酰)亚胺锂-乙二醇二甲醚/1,3二氧戊环+2%(w)硝酸锂电解液,以及4 mol·L^-1双氟磺酰亚胺锂-乙二醇二甲醚电解液,利用原子力显微镜研究了不同电解液体系中锂金属的生长行为,探讨了锂金属沉积形貌与其库仑效率之间的联系,为发展高效的锂金属负极提供了参考依据。     

丁磺酸内酯对锂离子电池性能及负极界面的影响

用循环伏安(CV)、电化学阻抗谱(EIS)、扫描电镜(SEM)、能谱分析(EDS)及理论计算等方法研究了添加剂丁磺酸内酯(BS)对锂离子电池负极界面性质的影响. 研究表明, 在初次循环过程中, BS具有较低的最低空轨道能量, 优先于溶剂在石墨电极上还原分解, 并形成固体电解质相界面膜(SEI膜). 在含BS的电解液中形成的SEI膜的热稳定性高, 在70 ℃下储存24 h后, 膜电阻和电荷迁移电阻大小基本保持不变, 而在不含BS的电解液中形成的SEI膜的热稳定性较差, 在70 ℃下储存24 h后, 膜电阻和电荷迁移电阻大小有明显的增加. 从BS对锂离子电池电化学性能影响的研究表明, 加入少量的BS能够显著提高锂离子电池的室温放电容量、低温及高温储存放电性能.     

多酚类化合物—丹宁酸用作锂金属负极电解液成膜添加剂

As the application of lithium-ion batteries in advanced consumer electronics, energy storage systems, plug-in hybrid electric vehicles, and electric vehicles increases, there has emerged an urgent need for increasing the energy density of such batteries. Lithium metal anode is considered as the "Holy Grail" for high-energy-density electrochemical energy storage systems because of its low reduction potential (-3.04 V vs standard hydrogen electrode) and high theoretical specific capacity (3860 mAh·g^-1). However, the practical application of lithium metal anode in rechargeable batteries is severely limited by irregular lithium dendrite growth and high reactivity with the electrolytes, leading to poor safety performance and low coulombic efficiency. Recent research progress has been well documented to suppress dendrite growth for achieving long-term stability of lithium anode, such as building artificial protection layers, developing novel electrolyte additives, constructing solid electrolytes, using functional separator, designing composite electrode or three-dimensional lithium-hosted material. Among them, the use of electrolyte additives is regarded as one of the most effective and economical methods to improve the performance of lithium-ion batteries. As a natural polyphenol compound, tannic acid (TA) is significantly cheaper and more abundant compared with dopamine, which is widely used for the material preparation and modification in the field of lithium-ion batteries. Herein, TA is first reported as an efficient electrolyte film-forming additive for lithium metal anode. By adding 0.15% (mass fraction, wt.) TA into the base electrolyte of 1 mol·L^-1 LiPF₆-EC/DMC/EMC (1 : 1 : 1, by wt.), the symmetric Li|Li cell exhibited a more stable cyclability of 270 h than that of only 170 h observed for the Li|Li cell without TA under the same current density of 1 mA·cm^-2 and capacity of 1 mAh·cm^-2 (with a cutoff voltage of 0.1 V). Electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, cyclic voltammetry (CV), and energy-dispersive X-ray spectroscopy (EDS) analyses demonstrated that TA participated in the formation of a dense solid electrolyte interface (SEI) layer on the surface of the lithium metal. A possible reaction mechanism is proposed here, wherein the small amount of added polyphenol compound could have facilitated the formation of LiF through the hydrolysis of LiPF₆, following which the resulting phenoxide could react with dimethyl carbonate (DMC) through transesterification to form a cross-linked polymer, thereby forming a unique organic/inorganic composite SEI film that significantly improved the electrochemical performance of the lithium metal anode. These results demonstrate that TA can be used as a promising film-forming additive for the lithium metal anode.     

锂离子电池电极界面特性研究方法

电极界面特性是影响锂离子电池充放电循环容量与稳定性的重要因素.本文总结了目前对电极界面特性进行研究的方法,主要包括传统的电化学方法、显微方法、谱学方法、电化学石英微晶天平等,重点论述了上述研究方法的原理、优缺点和在研究电极界面特性中的应用,以及这些方法相结合所取得的一些研究进展,并指出在今后的工作中,无论是对新材料的研...     

固态锂电池中金属锂负极与固体电解质界面的关键挑战

随着新能源汽车的快速发展,车用锂电池的安全性能备受关注。不同于传统锂离子电池采用可燃有机液体电解液,固态锂电池采用无机类固体电解质,具有不可燃、不漏液、高安全、长寿命等一系列优点。此外,固体电解质可兼容高容量金属锂负极,进而实现高能量密度(300 Wh/kg)。然而,由于固体电解质缺乏流动性,其与金属锂负极的界面问题已经成为制约固态锂电池发展的瓶颈。本文简要讨论了金属锂负极与固体电解质界面所存在的几项关键挑战:(1)界面润湿;(2)枝晶生长;(3)金属锂的利用率等问题,并介绍了针对这几项关键问题的近期研究进展。     

锂电池电极过程的原位电化学原子力显微镜研究进展

随着人类对能源的使用与存储需求不断增加,高能量密度和高安全性能的二次锂电池体系正在被不断地开发与完善.深入理解充放电过程中锂电池内部电极/电解质界面的电化学过程以及微观反应机理,有利于指导电池材料的优化设计.原位电化学原子力显微镜将原子力显微镜的高分辨表界面分析优势与电化学反应装置相结合,能够在电池运行条件下实现对电极/电解质界面的原位可视化研究,并进一步从纳米尺度上揭示界面结构的演化规律与动力学过程.本文总结了原位电化学原子力显微镜在锂电池电极过程中的最新研究进展,主要包括基于转化型反应的正极过程、固体电解质中间相的动态演化以及固态电池界面演化与失效分析.     

石墨负极在Et4NBF4＋LiPF6/EC＋PC＋DMC电解液中的电化学行为

在PC+EC+DMC复合溶剂体系中,研究了Et4NBF4(四氟硼酸四乙基铵)与LiPF6组成的复合盐电解质对石墨负极材料界面性质的影响.用循环伏安和恒电流充放电测试方法研究了电解液与石墨负极的相容性,通过傅里叶变换红外光谱(FTIR)对固体电解质中间相膜(SEI)的成分变化进行了研究.结果表明,电解液中的Et4NBF4参与了SEI膜的形成;当Et4NBF4浓度为0.2和0.5mol·L-1时,电池首次充放电不可逆容量损失明显减少,循环效率分别七升到76.O%和81.6%.Et4NBF4/LiPF6复合盐电解质改善了PC基电解质与石墨负极的相容性.     

Stabilizing the Electrochemistry of Lithium-Selenium Battery via In situ Gelated Polymer Electrolyte: A Look from Anode

Li metal possesses a high theoretical specific capacity,high electronic conductivity,and a low electrochemical potential,making it a promising anode material for building next-generation rechargeable metal batteries.In case conventional liquid electrolytes were used,and the anode using Li metal has been hindered by unstable(electro)chemistry at Li/electrolyte interface and the accompanied dendrite issue.Specifically,for the Li-Se batteries,the dissolution and shuttle of polyselenide intermediates lead to the deposition of poorly-conductive species on the anode,which further aggravates the chemical environment at the anode.In this work,we proposed to stabilize the Li-Se electrochemistry by constructing a gel polymer electrolyte via in situ gelations of conventional ether-based electrolytes at room temperature.The results demonstrate that the in situ gelated electrolyte helps to build electrochemically stable electrode/electrolyte interfaces and promote the efficient transfer of charge carriers across the interface.Compared with the liquid electrolytes,the gelated electrolyte shows improved chemical compatibility with the Li metal anode,which effectively alleviates the unfavorable side reactions and dendrite formation at the anode/electrolyte interface,and the polyselenide shuttle from the cathode to the anode.As a result,the Li-Se battery shows a higher Coulombic efficiency and improved cycling performance.     

In situ analysis of interfacial reactions between negative MCMB,lithium electrodes,and gel polymer electrolyte

The interfacial properties of mesocarbon-microbeads (MCMB) and lithium electrodes during charge process in poly (vinylidenefluoride-co-hexafluoropropylene)-based gel electrolyte were investigated by in situ Raman microscopy, in situ Fourier transform-infrared (FTIR) spectroscopic methods, and charge–discharge, electrochemical impedance spectroscopy techniques. For MCMB electrode, the series phase transitions from initial formation of the dilute stage 1 graphite intercalation compound (GIC) to a stage 4 GIC, then through a stage 3 to stage 2, and finally to stage 1 GIC was proved by in situ Raman spectroscopic measurement. The formation of solid electrolyte interface (SEI) films formed on MCMB and metal lithium electrode was studied by in situ reflectance FTIR spectroscopic method. At MCMB electrode surface, the solvent (mostly ethylene carbonate) decomposed during charging process and ROCO₂Li may be the product. ROCO₂Li, ROLi, and Li₂CO₃ were the main composites of SEI film formed on lithium electrode, not on electrodeposited lithium electrode or lithium foil electrode.     

人工界面层在金属锂负极中的应用

金属锂具有极高的比容量(3860 mAh·g^?1)和最低的电化学反应电位(相对标准氢电位为?3.040 V),被认为是高能量密度二次电池最具潜力的负极材料。然而金属锂负极界面稳定性差、不可控的枝晶生长、沉积/剥离过程中巨大的体积变化等严重阻碍了金属锂负极的商业化应用。在金属锂表面构建一层物理化学性质稳定的人工界面保护层被认为是解决金属锂负极界面不稳定和枝晶生长,缓解体积膨胀带来的界面波动等一系列问题的有效手段。本综述依据界面传导性质,从离子导通而电子绝缘的人工固态电解质界面(SEI)层、离子/电子混合传导界面、纳米界面钝化层三个部分对人工界面保护层进行了归纳总结。分析了人工界面保护层的物质结构与性能之间的构效关系,探讨了如何提高人工界面保护层的物理化学稳定性、界面离子输运、界面强度与柔韧性、界面兼容性等。最后,指出用于金属锂负极的人工界面保护层目前面临的主要挑战,并对其未来的发展进行了展望。     

In situ scanning probe microscopy and new perspectives in analytical chemistry

The resolution of scanning tunnelling microscopy (STM) and other scanning probe microscopies is unprecedented but the techniques are fraught with limitations as analytical tools. These limitations and their relationship to the physical mechanisms of image contrast are first discussed. Some new options based on in situ STM, which hold prospects for molecular- and mesoscopic-scale analytical chemistry, are then reviewed. They are illustrated by metallic electro-crystallisation and -dissolution, and in situ STM spectroscopy of large redox molecules. The biophysically oriented analytical options of in situ atomic force microscopy, and analytical chemical perspectives for the new microcantilever sensor techniques are also discussed.     

Recent progress in the application of in situ atomic force microscopy for rechargeable batteries

High energy density batteries are urgently required for sustainable life. The intrinsic understanding of the reaction mechanism at the interfaces is essential for the progress. In this short overview, recent advances in rechargeable batteries by in situ atomic force microscopy are summarized, providing nanoscale information on the solid product evolution and metal plating/stripping inside working batteries. Besides, the multifunctional imaging of the morphology along with mechanical and electrical properties can be achieved to assist further interfacial design. Extensive applications of in situ atomic force microscopy are encouraged to explore the electrochemical mechanism and advanced engineering.     

基于原子力显微镜的高分子单分子力学研究

原子力显微镜(AFM)从根本上改变了人们对单个原子和分子的作用和认识方式。单分子力谱是基于原子力显微镜力的测量方法。概速了近年来利用基于原子力显微镜的单分子力谱研究单个高分子分子内及分子闻作用力的进展。     

自生氧化铝颗粒增强铝基复合材料的扫描电镜和原子力显微镜的对比研究

用扫描电镜（ＳＥＭ）、原子力显微镜（ＡＦＭ）等分析技术研究了一种Ａｌ／Ａｌ２Ｏ３自生颗粒复合材料的微观形貌，结果表明，７００～７５０℃气－液反应生成的氧化铝自生颗粒的典型尺寸为亚微米级，颗粒与基体之间具有热力学稳定性。