锂离子电池非水电解质锂盐的研究进展

新型电解质锂盐主要包括含螯合硼阴离子、螯合磷阴离子、全氟膦阴离子、烷基磺酸阴离子、全氟烷基、亚胺基的有机锂盐及有机铝酸锂盐.本文综述了近年来在新型电解质锂盐研究与探索方面的成果,介绍了锂离子电池电解质锂盐的合成方法、组成与结构、化学和电化学性能及其与结构的关系,并阐述今后电解质锂盐研究的可能发展方向及研究方法.     

Li-SGO掺杂半互穿网络型多孔单离子传导聚合物复合电解质的制备

本文成功制备了磺酸锂功能化石墨烯,通过原位聚合方式成功将其添加到单离子传导聚合物电解质中制备出磺酸锂功能化石墨烯改性半互穿网络型多孔单离子传导聚合物复合电解质.与未掺杂磺酸锂功能化石墨烯半互穿网络型多孔单离子传导聚合物电解质相比,该电解质具有更高的孔隙率、吸液率、机械拉伸强度和离子电导率.电化学测试结果表明,掺杂磺酸锂...     

锂二次电池中的原位聚合电解质

聚合物电解质主要分为凝胶聚合物电解质和固态聚合物电解质两种类型,均能够提升锂二次电池的性能。其中,凝胶聚合物电解质是利用增塑剂实现聚合物基质的凝胶化,将有机液态电解液固定在三维网络结构中,因此同时具备液态的离子扩散速率和固态材料的机械性能;而固态聚合物电解质是一种完全没有液态电解质的体系,利用聚合物基体的极性实现锂盐的解离,以聚合物分子链的运动实现离子传输。相对于传统的非原位法制备的聚合物电解质而言,原位聚合反应制备的聚合电解质能够有效改善电解质与电极的界面相容性、简化电池组装工艺、降低制造成本。本文综述了当前原位聚合电解质在锂二次电池中应用的研究进展,并展望了原位聚合电解质的应用前景和未来挑战。     

红外光谱研究PEO基离子液体聚合物电解质

以聚氧化乙烯(PEO)为聚合物基体, 双三氟甲基磺酸亚酰胺锂(LiTFSI)为锂盐, 加入不同量的离子液体(BMIMPF₆)为增塑剂, 制备离子液体聚合物电解质. 运用发射FTIR光谱技术实时监测所制备聚合物电解质的结构随温度的变化. 结合FTIR透射光谱\, SEM和XRD的研究结果分析了离子液体对离子电导率的影响, 并初步提出离子导电增强机制.     

塑晶基离子液体合成及其电化学性能

通过简单、易于工业化的重结晶方法制备了高纯1-甲基-1-乙基吡咯烷鎓双(三氟甲基磺酰)亚胺盐(P₁₂TFSI)塑晶化合物. 在此化合物中加入30% (摩尔分数, x)双(氟磺酰)亚胺锂(LiFSI)后, 得到P₁₂TFSI/LiFSI 塑晶基离子液体. 采用循环伏安法、恒电压极化法及恒电流充放电法等电化学方法考察了该离子液体的电化学窗口、铝箔集流体的腐蚀性及电池性能. 结果表明, 该离子液体电解质具有5.00 V的电化学窗口, 室温离子电导率达到0.92 mS·cm^-1, 且不腐蚀Al 集流体. 以该塑晶离子液体作为电解液组装的实验电池LiCoO₂/Li 表现出良好的充放电特性及循环性能, 在较低倍率下能够和使用碳酸酯类电解液组装的实验电池的性能相媲美. 在4.50 V高电压下, 循环20周后, 容量仍能保持在175 mAh·g^-1, 容量保持率为95.1%. 这些结果说明该离子液体在高性能锂二次电池中具有良好的应用前景.     

锂金属电池用三维半互穿网络聚合物电解质的制备

锂金属电池作为下一代高比能量电池技术受到人们越来越广泛的关注。然而由锂枝晶生长引发的安全问题是锂金属电池商业化面临的最大挑战之一。具有高锂离子迁移数和离子电导率的聚合物电解质是抑制锂枝晶生长的重要策略之一。本文将季戊四醇四丙烯酸酯和自由基引发剂AIBN添加至商业化电解液中,采用具有单离子传导功能的多孔聚合物电解质为锂金属电池的电解质隔膜,通过在电池内部发生热诱导原位聚合制备三维半互穿网络单离子传导聚合物电解质,达到提高电解质隔膜离子电导率和机械拉伸性能,以及有效抑制锂枝晶生长的目的。通过该策略的实施,成功获得了室温离子电导率0.53 mS·cm^-1和锂离子迁移数0.65的良好结果。应用于锂金属电池,证明该电解质能够有效抑制锂枝晶的生长和倍率性能的提高,为锂金属电池的开发提供了良好的解决路径。     

用于锂离子电池聚合物电解质的组成、结构和性能

聚合物电解质是全固态锂离子电池的重要组成部分, 其电导率对电池的性能有很重要的影响.本文综述了聚合物电解质的组成、结构和性能对锂 离子电池导电率影响的最新研究进展,特别是介绍了聚合物-碱金属盐复合电解质和聚离子体电解质两个体系的研究进展.     

新型梳状聚甲基丙烯酸酯固态聚合物电解质的制备及导电性能研究

采用溶液聚合方法,以甲基丙烯酸甲酯、聚乙二醇单甲醚甲基丙烯酸酯为共聚单体,制备一种新型无规梳状聚合物,并研究了一系列掺杂不同含量高氯酸锂全固态聚合物电解质的导电性能.FTIR、1H-NMR结果证实了新型梳状聚合物具有无规梳状结构特征.DSC和XRD结果表明了聚合物电解质主要是以无定型状态存在.SEM和FTIR结果证实了当锂盐含量低于16 wt%时,锂盐在聚合物中具有良好的溶解性,ClO4-主要以单离子状态存在,此时聚合物电解质30℃离子电导率达到最大值,为4.81×10-5S/cm.当锂盐含量超过16wt%时,Li+ClO4-离子对含量明显增多,表明了锂盐溶解性能下降,同时聚合物电解质离子电导率显著下降,这主要是锂盐增加导致离子的缔合增强,不利于离子的传导所致.     

染料敏化纳米薄膜太阳电池中离子液体基电解质的研究进展

综述了离子液体基电解质在染料敏化纳米薄膜太阳电池中的研究及应用进展，详细论述了多种离子液体基电解质系统对染料敏化纳米薄膜太阳电池性能的影响，并比较了这些系统的优缺点. 根据胶凝剂的不同分别论述了离子液体基电解质的固化及其对电池性能的影响. 评述了离子液体基电解质在大面积电池中的应用，并对离子液体基电解质未来发展方向进行了展望.     

PEO基锂硫二次聚合物电池

分别对单质硫和PABTH (polyanthra [1 ,9 ,8 -b,c,d,e][4 ,10 ,5 -b ,c ,d ,e ]bis-[1,6,6a(6a-S^Ⅳ)trithia]pentalene)在PEO (polyethylene oxide)基聚合物电解质中的电化学性能进行了研究. 研究发现单质硫和PABTH在PEO基聚合物电解质中都存在放电产物溶解现象, 说明醚基电解液即使以聚合物形式存在(如PEO基聚合物电解质)也不能有效抑制硫电极放电产物的溶解损失. 因此, 必须设计合成具有特定结构的电解质溶剂, 以抑制硫电极放电产物的溶解. 另外, 硫及有机硫化物在PEO基聚合物电解质中的利用率较低, 这主要是由于硫及有机硫化物不是离子导体, Li^＋在硫及有机硫化物中的扩散系数较低, 同时, 传输Li^＋的PEO分子量较大, Li^＋不能被有效传输至材料颗粒的内部. 因此, 全固态聚合物电解质不适合锂硫二次电池, 液态小分子电解质溶剂更有利于锂硫二次电池发挥其高比容量.     

聚乙烯醇基水凝胶聚合物电解质超级电容器的研究

以2-丙烯酰胺基-2-甲基丙磺酸（AMPS）作引发剂引发交联聚乙烯醇（PVA）-戊二醛（GA）制备水凝胶聚合物电解质并组装成超级电容器.分别由红外光谱、交流阻抗、循环伏安与恒电流充放电曲线测定该凝胶聚合物电解质及超级电容器的电化学性能.结果表明,该聚合物电解质电导率可达1.23 mS/cm（室温）.而且,以1.0 g AMPS引发0.05mL GA（5 %）与1.0 g PVA交联,制得的凝胶聚合物电解质超级电容器比电容可达139F/g,50次充放电后其值仍于80%以上.     

A Gel Polymer Electrolyte with 2D Filler-reinforced for Dendrite Suppression Li-Ion Batteries

Gel polymer electrolytes (GPEs) incorporate both the high ionic conductivity of organic liquid electrolyte and the high safety performance of all-solid-state electrolytes (ASSEs), greatly improving the electrochemical performance of solid polymer electrolytes (SPEs). However, the practical application of GPEs is still limited by inferior interface compatibility, lithium dendrites, etc. Herein, we prepared GPEs based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) further co-blended the two-dimensional sheet inorganic filler hectorite and poly(methyl methacrylate) (PMMA) to improve the mechanical and electrochemical properties of the GPEs. When the content of PMMA and hectorite is optimal, this GPEs have an ionic conductivity of 1.06×10⁻³ S cm⁻¹ and outstanding lithium symmetric cells cycle time of more than 3000 h, indicating that the introduction of filler effectively inhibits the growth of lithium dendrites at room temperature. Moreover, the GPEs adopt a relatively simple solution casting method to provide a fresh idea for the synthesis of high-performance GPEs.     

Synthesis,electrolyte properties and solar cell performance of hyperbranched poly(aryl-ether-urea)s

Hyperbranched poly(aryl-ether-urea)s with phenyl, N,N-dimethylamino ethyl and polyethylene oxide end-groups linked through urethane group – HBPEU-1, HBPEU-2 and HBPEU-3 respectively – were synthesized from an AB₂-type blocked isocyanate monomer and characterized by FT-IR, ¹H-NMR, SEC-MALLS, TGA and DSC techniques. The molecular weight of the polymers were found to be ranged from 4.9 × 10³ ? 1.96 × 10⁴ g/mol. The TGA results showed that the polymers decompose between 175°C – 220°C. In the DSC curves, HBPEU-1 and HBPEU-3 showed T_g at 160°C and 53°C respectively, whereas HBPEU-2 did not showed clear T_g. All the three polymers were converted into polymer electrolytes by doping with LiI/I₂. The doped polymers showed remarkably high ionic conductivity, up to 222 – 277 times compared to the un-doped polymers and the highest conductivity was observed with doped HBPEU-2. The TiO₂ based dye-sensitized solar cells (DSSCs) were fabricated using the doped polymer electrolytes and their performance was tested; HBPEU-2 showed good performance by yielding energy conversion efficiency (η) of 4.5%.     

Recent research progress on quasi-solid-state electrolytes for dye-sensitized solar cells

Dye-sensitized solar cells(DSSCs) are the most promising, low cost and most extensively investigated solar cells. They are famous for their clean and efficient solar energy conversion. Nevertheless this, long-time stability is still to be acquired. In recent years research on solid and quasi-solid state electrolytes is extensively increased. Various quasi-solid electrolytes, including composites polymer electrolytes, ionic liquid electrolytes,thermoplastic polymer electrolytes and thermosetting polymer electrolytes have been used. Performance and stability of a quasi-solid state electrolyte are between liquid and solid electrolytes. High photovoltaic performances of QS-DSSCs along better long-term stability can be obtained by designing and optimizing quasi-solid electrolytes. It is a prospective candidate for highly efficient and stable DSSCs.     

A novel composite polymer electrolyte containing room-temperature ionic liquids and heteropolyacids for dye-sensitized solar cells

A novel composite polymeric gel comprising room-temperature ionic liquids (1-butyl-3-methyl-imidazolium-hexafluorophosphate, BMImPF₆) and heteropolyacids (phosphotungstic acid, PWA) in poly(2-hydroxyethyl methacrylate) matrix was successfully prepared and employed as a quasi-solid state electrolyte in dye-sensitized solar cells (DSSCs). These composite polymer electrolytes offered specific benefits over the ionic liquids and heteropolyacids, which effectively enhanced the ionic conductivity of the composite polymer electrolyte. Unsealed devices employing the composite polymer electrolyte with the 3% content of PWA achieved the solar to electrical energy conversion efficiency of 1.68% under irradiation of 50 mW cm⁻² light intensity, increasing by a factor of more than three compared to a DSSC with the blank BMImPF₆-based polymer electrolyte without PWA. It is expected that these composite polymer electrolytes are an attractive alternative to previously reported hole transporting materials for the fabrication of the long-term stable quasi-solid state or solid state DSSCs.     

Ionic conductivity and compatibility studies of blends of poly(methyl methacrylate) and poly(propylene glycol) complexed with LICF3SO3

Stable to atmospheric moisture, adhesive and transparent polymer electrolytes have been prepared by blending poly(methyl methacrylate) (PMMA) with poly(propylene glycol)-425/LiCF₃SO₃ complexes. The blending of the polymers has been achieved by a method developed in our laboratory: free radical polymerization of methylmethacrylate in the polyether/salt matrix. A series of polymer blend complexes varying in PMMA content (up to 20% by weight) and oxygen/metal ratios (25, 16, and 8) have been synthesized and their properties studied. All the samples prepared in this study were found to be optically clear unlike the higher molecular weight poly(propylene glycol)-2000 (PPG-2000) system which required a minimum salt concentration to compatibilize a specific amount of PMMA with PPG. The mechanisms by which the salt holds the otherwise incompatible polymers together in a single phase have been investigated by FT-IR. Our studies show a weak coupling of the ether oxygens in the PPG with the ester groups of the PMMA through the lithium cations. Discrete changes has been observed in the FT-IR spectrum of PMMA when doped with the lithium salt hitherto unnoticed with other dopants. Gel permeation chromatography results of the PMMA samples isolated from the solid electrolytes indicate the molecular weight to vary between 43000 and 121000 with relatively narrow distributions, 1.6?2.0. The ionic conductivities of the polymer blend electrolytes were fairly high (10^?5 S/cm) at room temperature. The PMMA neither significantly influenced the T_g of the blend complexes nor effected the ionic conductivities drastically. The ionic conductivity as a function of temperature followed the empirical Vogel-Tammann-Fulcher equation. The blending of PMMA with PPG/LiCF₃SO₃ complexes was found to impart good adhesiveness to the solid electrolytes while making them stable to atmospheric moisture. © 1992 John Wiley & Sons, Inc.     

Dynamics and lithium binding energies of polyelectrolytes based on functionalized poly(para-phenylene terephthalamide)

Polyelectrolyte materials are an interesting class of electrolytes for use in fuel cell and battery applications. Poly(para-phenylene terephthalamide) (PPTA, Kevlar) is a liquid crystalline polymer that, when sulfonated, is a polyelectrolyte that exhibits moderate ion conductivity at elevated temperatures. In this work, quasi-elastic neutron scattering (QENS) experiments were performed to gain insight into the effect of the presence of lithium counterions on the chain dynamics in the material. It was found that the addition of lithium ions decreases the dynamics of the chains. Additionally, the binding of lithium ions to the sulfonic acids groups was investigated by density functional theory (DFT) calculations. It was found that the local surroundings of the sulfonic acid group have very little effect on the lithium-ion binding energy. Binding energies for a variety of different systems were all calculated to be around 150 kcal/mol. The DFT calculations also show the existence of a structure in which a single lithium ion interacts with two sulfonic acid moieties on different chains. The formation of such "electrostatic cross-links" is believed to be the source of the increased tendency to aggregate and the reduced dynamics in the presence of lithium ions.     

Distinct difference in ionic transport behavior in polymer electrolytes depending on the matrix polymers and incorporated salts

Two different electrolyte salts, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and a room temperature ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMITFSI), were incorporated into network polymers to obtain ion-conductive polymer electrolytes. Network polymers of poly(ethylene oxide-co-propylene oxide) (P(EO/PO)) and poly(methyl methacrylate) (PMMA) were chosen as matrixes for LiTFSI and EMITFSI, respectively. Both of the polymer electrolytes were single-phase materials and were completely amorphous. Ionic conductivity of the polymer electrolytes was measured over a wide temperature range, with the lowest temperatures close to or below the glass transition temperatures (Tg). The Arrhenius plots of the conductivity for both of the systems exhibited positively curved profiles and could be well fit to the Vogel-Tamman-Fulcher (VTF) equation. The conductivity of the PMMA/EMITFSI electrolytes was higher at most by 3 orders of magnitude than that of the LiTFSI/P(EO/ PO) electrolytes at ambient temperature. When the ideal glass transition temperature, T0 (one of the VTF fitting parameters), was compared with the Tg, a difference in the ionic conduction was apparent in these systems. In the P(EO/PO)/LiTFSI electrolytes, the T0 and Tg increased in parallel with salt concentration and the T0 was lower than the Tg by ca. 50 degrees C. On the contrary, the difference between the T0 and the Tg increased with increasing content of PMMA in the PMMA/EMITFSI electrolytes, with the observed difference in the concentration range studied reaching up to ca. 100 degrees C. The conductivity at the Tg, sigma(Tg), for the LiTFSI/P(EO/PO) electrolytes was on the order of 10(-14-)10(-13) S cm(-1) and increased with increasing salt concentration, whereas that for the PMMA/EMITFSI polymer electrolytes reached 10(-7) S cm(-1) when the concentration of PMMA was high. The ion transport mechanism was discussed in terms of the concepts of coupling/decoupling and strong/fragile for the two different polymer electrolytes.     

Preparation and ionic conductivities of the plasticized polymer electrolytes based on poly(methyl methacrylate-co-alkali metal methacrylate)

Ionic conductivities of the polymer electrolytes prepared from the ionomer (poly(methyl methacrylate-co-alkali metal methacrylate)), lithium perchlorate, and ethylene carbonate as a plasticizer, were studied as a function of the ion content and the alkali-metal cation of the ionomer. It was possible to obtain tough films with room-temperature ionic conductivities of ∼ 10^-3 S/cm. The maximum ion conductivities of the polymer electrolytes were obtained at the ion content of 5 mol % for both Li and Na ionomer. The effects of the ion content of the ionomer on the ionic conductivities of the polymer electrolytes were mainly interpreted in terms of the characteristics of the ion aggregate formed in the polymer electrolytes. The thermal dependence of the ionic conductivity was shown to be a non-VTF pattern in some of the polymer electrolytes investigated, which is expected to be due to the presence of the ion aggregate. © John Wiley & Sons, Inc.     

Performance of gelled-type dye-sensitized solar cells associated with glass transition temperature of the gelatinizing polymers

Poly(methyl acrylate) (PMA), poly(vinyl acetate) (PVAc) and poly(n-isopropylacrylamide) (PNIPAAm) with their respective T_g of 6, 32, and 145 °C were employed to gel the LiI/I₂/tertiary butylpyridine electrolyte system for preparation of the gelled-type dye-sensitized solar cells (DSSC). The light-to-electricity conversion efficiencies of DSSCs gelled by PMA, PVAc, and PNIPAAm were 7.17%, 5.62%, and 3.17%, respectively under simulated AM 1.5 sunlight irradiation, implying that utilizing the polymer of lower T_g to gel the electrolytes leaded to better performance of the DSSCs. Their short-circuit current density and IPCE also showed the similar trend. Electrochemical impedance spectroscopy of the gelled DSSCs revealed that utilizing the polymer of lower T_g resulted in lower impedance associated with the Nernstian diffusion within the electrolytes. The results were consistent with the observation that the molar conductivity of gelled electrolytes was higher as the polymer of lower T_g was applied, which can be justified by Vogel-Tammann-Fulcher (VTF) equation.