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锂离子电池是能源储存和利用的一项关键技术,能量密度已成为现代电池发展中的一个关键指标。硅基负极由于其较高的理论比容量,得到广泛关注,但硅基材料存在严重的体积膨胀问题。功能性添加剂对电池性能有明显的改善效果,是电解液体系不可缺少的部分,具有“用量小,见效快”的特点,通过成膜添加剂形成稳定的固态电解质界面(SEI)膜进而稳定电极电解液界面,改善硅基负极电池性能。本文总结了近年来硅基负极电解液成膜添加剂的研究进展,对成膜添加剂按照官能团或元素进行分类论述,并对多组分成膜添加剂的协同作用进行了简要阐述。最后,针对目前硅基负极电解液添加剂的研究现状进行了总结,并展望了未来的研究方向。 相似文献
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稳定的固体电解质界面(SEI)是提高锂离子电池电化学性能的关键,用电解液添加剂是改善锂离子电池性能最经济有效的方法之一。本文综述了近五年间包括不饱和酯化合物、含硫化合物、锂盐、无机化合物等作为电解液成膜添加剂在锂离子电池中的研究进展和作用机理,对它们的优缺点进行了评价,最后进行了总结和展望。未来成膜类添加剂的研究思路应该为:(1)应以有机物种为主,能够形成弹性模量小的SEI膜,便于适应阳极材料产生的膨胀行为。(2)添加剂要尽量保证形成的SEI膜与石墨等阳极材料产生良好的黏结,因此添加剂形成的聚合物的聚合度不能太小。(3)在没有性能极其优秀的成膜添加剂出现之前,添加剂的分子结构可以在现有的添加剂的基础上进行结构的优化或者官能团的设计。(4)重点攻关当前添加剂的应用的问题,提高添加剂的合成技术,降低合成成本。 相似文献
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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。 相似文献
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从电解液的组成和功能添加剂两大方面,综合阐述了锂离子电池电解液的研究进展。在电解液组成方面,找到具有高的介电常数和能在石墨类电极表面形成有效SEI的有机溶剂,并且找到具有良好电导率、稳定电化学性能的电解质。而电解液功能添加剂方面,重点研究是找到改善电池安全性能的添加剂。 相似文献
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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。 相似文献
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利用不同测试方法研究了锰酸锂表面SEI膜的形成条件及其主要构成。研究结果表明:锰酸锂表面SEI膜在第一周循环过程中形成,在第二周循环过程中会经历一个膜的重整过程,其膜厚度为5.08 nm;SEI膜组分是由于电极材料表面所发生的化学反应和电化学反应所产生,其主要构成为氟化锂、碳酸锂和有机锂化合物,有机锂化合物包括CH3OLi、CH3OCO2Li、CH3CH2Li、CH3CH2OLi、(CH2OCO2Li)2、LiCH2CH2OCO2Li、LiOCH2CH2OCO2Li等。 相似文献
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Jie Shu Miao Shui Fengtao Huang Dan Xu Yuanlong Ren Lu Hou Jia Cui Jinjin Xu 《Electrochimica acta》2011,(8):3006
The chemical and electrochemical stability of Cu current collectors in electrolyte for lithium-ion batteries is investigated. During long-term storage, the surface section of Cu foil is oxidized to copper compounds along with the reduction reaction of electrolyte. A continuous surface film can be formed on the Cu current collector after the foil is immersed in electrolyte for lithium ion batteries at room temperature for 30 days. This surface film is composed of inorganic compounds located in the inner layer and organic/inorganic mixed components stayed outside. It comes from the spontaneous reaction at the interface between Cu foil and electrolyte for the existence of trace water in electrolyte. Different from SEI film spontaneous formation during storage, surface film generated on Cu foil during electrochemical process shows different characteristic and mechanism. By using metal lithium as counter electrode, SEI film on Cu foil in Cu foil/metal Li battery is formed from surface chemical species floating from lithium counter electrode and electrochemical oxidation/reduction process. In contrast, thinner SEI film can be generated merely from electrochemical electrolyte decomposition and precipitation. All the evidences reveal that the structure of SEI film from different conditions is similar, which shows inorganic fluorides located in the inner layer and organic/inorganic mixed lied in the outer layer. 相似文献
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锂离子电池首次充、放电时石墨负电极与电解液界面所发生的反应 总被引:1,自引:0,他引:1
采用恒电流充、放电——原位XRD法对锂离子电池(LIB)首次充、放电过程进行了研究。实验结果表明,LIB首次充电时电解液于石墨负电极的界面处发生还原反应,生成了电子不可导而锂离子可导的固体电解质中介相(SEI)薄膜。FTIR分析结果证明SEI膜系由无定形碳酸锂和烷基碳酸锂组成。恒电流充、放电实验和循环伏安实验结果表明,如果所选择的电解液(例如EC基电解液)在石墨负电极表面的还原反应很缓和,反应中所产生气体的量和速率很小,则在石墨负电极表面将形成薄而致密的SEI膜。薄而致密的SEI膜所消耗的Li^+量小,可以降低首次充电时的不可逆容量,同时减小Li^+对石墨进行插层和脱层时的阻力,增大LIB的充、放电容量,提高充、放电效率。 相似文献
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The lithium electrode is always covered by a film of lithium chloride which acts as solid electrolyte interphase (SEI). Macropolarization curves indicate that the Tafel slope is greater than 3 V for electrodes having SEI thicker than 400 Å. This confirms that the rds for the deposition-dissolution process is the migration of lithium cations through the SEI. Increasing the electrolyte concentration increases the interfacial capacitance and decreases the resistivity of the SEI. This is explained in terms of the effect of LiAlCl4 concentration on the concentration of the lattice defects. The effect of the concentration of the electrolyte on the resistivity of the SEI decreases as the thickness of the SEI is increased. The growth rate of the SEI increases as the concentration of the electrolyte is increased. 相似文献
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Mario Wachtler Margret Wohlfahrt-Mehrens Sandra Ströbele Jan-Christoph Panitz Ulrich Wietelmann 《Journal of Applied Electrochemistry》2006,36(11):1199-1206
The film formation behaviour of lithium bis(oxalato)borate (LiBOB), a new electrolyte salt for lithium batteries, on graphite, carbon black and lithium titanate is reported. LiBOB is actively involved in the formation of the solid electrolyte interphase (SEI) at the anode. Part of this formation is an irreversible reductive reaction which takes place at potentials of around 1.75 V vs Li/Li+ and contributes to the irreversible capacity of anode materials in the first cycle. Carbon black interacts strongly with LiBOB-based electrolytes, which results in strong film formation and loss of electronic conductivity within the composite electrode. In LiBOB-based electrolytes the electrode kinetics increase in the order: carbon black << fine particulate graphite ~ metal powder, due to decreased film formation of the conductive additive. The influence of various solvents, surfactant additives, and potential impurities was also studied. 相似文献
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Yanbao Fu Cheng Chen Chenchen Qiu Xiaohua Ma 《Journal of Applied Electrochemistry》2009,39(12):2597-2603
In this research, we investigated the potential application of vinyl ethylene carbonate (VEC) and ethylene carbonate (EC)
as solid electrolyte interface (SEI) film-forming additive in 1-ethyl-3-methylimidazolium (EMI)-bis(trifluoromethyl-sulfonyl)
imide (TFSI)-LiTFSI ionic liquid electrolyte (IL). The electrochemical performance of natural graphite (NG7) was studied in
LiTFSI/EMI-TFSI containing different weight percent of EC/VEC via cyclic voltammetry (CV), electrochemical impedance spectrum
(EIS), and galvanostatic charge/discharge cycles. Temperature effect on the discharge/charge performance of NG7 electrode
in the researched IL electrolyte was also discussed. 相似文献