锂离子电池PMMA-VAc聚合物电解质的制备与性质研究

以甲基丙烯酸甲酯(MMA)和醋酸乙烯酯(VAc)为单体, 用乳液聚合法合成聚甲基丙烯酸甲酯-醋酸乙烯酯聚合物(PMMA-VAc), 并以此聚合物制备了新型聚烯烃膜支撑的聚合物膜及聚合物电解质. 用红外光谱(FTIR)、凝胶色谱(GPC)、差热和热重分析(DSC/TG)、扫描电镜(SEM)及电池充放电实验等方法研究了聚合物、聚合物膜和聚合物电解质的性质. 红外光谱结果表明, MMA与VAc通过各自的C＝C双键打开聚合成PMMA-VAc. PMMA-VAc易于分散在混合碳酸酯溶剂中并形成凝胶, 凝胶粘度随PMMA-VAc浓度的增加而增加, 当浓度为4%时成膜效果最佳. PMMA-VAc膜具有大量的微孔结构, 具有极强的吸液性能. PMMA-VAc膜具有良好的热稳定性: 在380 ℃范围内保持稳定. 聚烯烃膜支撑的PMMA-VAc膜室温下的离子电导率为1.85×10^－3 S•cm^－1, 用作为锂离子电池的聚合物电解质时, 电池具有良好的循环稳定性和倍率性能.     

P(VAc-MA)/PMMA为基体的聚合物电解质制备及其在电致变色器件中的应用

以醋酸乙烯酯(VAc)和丙烯酸甲酯(MA)为单体, 采用半连续种子乳液聚合法制备了无规共聚物P(VAc-MA), 以PMMA与P(VAc-MA)的共混物为基体制备了聚合物电解质. 用红外光谱(FTIR)、X射线衍射(XRD)、热重分析(TG)、紫外光谱(UV)、力学性能测试及电化学交流阻抗等方法研究了聚合物、聚合物膜和聚合物电解质的性质. 结果表明, VAc与MA通过打开各自的CC键聚合生成P(VAc-MA); P(VAc-MA)与PMMA共混后结晶状态发生了变化, 增加了无定形相区, 降低了链段运动的能量壁垒, 提高了热稳定性和拉伸强度. 以P(VAc-MA)/PMMA为基体的聚合物电解质膜具有很高的透明性, 最大室温电导率达到1.17×10-3 S/cm; 离子电导率随着温度的升高而迅速增加, 电导率-温度曲线符合Arrhenius方程; 将此电解质用于全固态电致变色显示器件显示出优良的性能.     

尿素作为造孔剂对聚乙烯支撑的PAMS聚合物电解质性能的改进

采用乳液聚合法合成聚(丙烯腈-甲基丙烯酸甲酯-苯乙烯) (P(AN-MMA-ST)或者共聚物PAMS), 并利用尿素作为造孔剂制备了聚乙烯(PE)支撑的PAMS聚合物膜(PE-PAMS-U)及凝胶聚合物电解质(GPE). 利用傅里叶变换红外(FTIR)光谱、X射线衍射(XRD)、扫描电子显微镜(SEM)、热重(TG)分析、线性电位扫描(LSV)、电化学阻抗谱(EIS)以及充放电等方法对PAMS聚合物以及PE支撑的聚(丙烯腈-甲基丙烯酸甲酯-苯乙烯) (PE-PAMS)聚合物隔膜及凝胶聚合物电解质的性能进行了研究. 结果表明, 利用尿素作为造孔剂可以提高PE-PAMS凝胶聚合物的性能. 由于尿素的加入, 聚合物膜呈现均匀的微孔结构, 室温下的电导率从1.1×10^-3 S·cm^-1提高到2.15×10^-3 S·cm^-1. 同时, 锂电极/聚合物电解质界面上的电荷传递电阻也从480 Ω·cm²降低到 250 Ω·cm². 电化学稳定窗口为5.0 V. 电池(Li/PE支撑的GPE/LiCoO₂)的测试证明, 用尿素作为造孔剂的凝胶聚合物锂离子电池表现出优良的倍率性能和循环性能.     

PAMPSLi/P(MMA-VAc)为基体的聚合物电解质

将聚(2-丙烯酰胺-2-甲基丙磺酸锂)(PAMPSLi)和聚(甲基丙烯酸甲酯-醋酸乙烯酯)[P(MMA-VAc)]与LiClO₄共混, 制备了复合聚合物电解质膜. 用FTIR, TG, XRD, DMA, SEM及电化学交流阻抗和机械性能测试对聚合物及其电解质膜的结构和性能进行了表征. 结果表明, PAMPSLi与P(MMA-VAc)共混后结晶状态发生变化, 交联网络变得密实, 提高了热稳定性和拉伸强度, 聚合物电解质膜含有较多微孔结构, 孔径为5~10 μm; 在20 ℃时, 当n(MMA)∶n(VAc)=2∶8, m(PAMPSLi)∶m[P(MMA-VAc)]=5∶95, m(LiClO₄)∶m(copolymer)=15∶85时, 聚合物电解质膜电导率可达到1.68×10^-3 S/cm, 且电导率未出现随LiClO₄含量的进一步增加而下降的现象. 将此电解质用于全固态电致变色显示器件表现出了优良的性能. 对加入PAMPSLi后聚合物电解质膜电导率和热稳定性提高的原因进行了初步探讨.     

新型PMMA基聚合物电解质的研制

制备了聚甲基丙烯酸甲酯（PMMA）基聚合物电解质，通过加入交联剂使其形成网状结构，提高了聚合物电解质的机械性能.对MMA以及交联剂的含量作了优化，并测试了聚合物电解质的温度特性.测试结果表明,MMA、EGD(二甲基丙烯酸乙二醇酯)和电解液(LiBF4/EC DMC)含量分别为25％、2％、73％(质量分数）时，所制备的聚合物电解质具有较高的电导率，室温条件下可以达到2×10－3 S•cm－1，电化学窗口为4.8 V.用其作为电解质组装的聚合物锂离子电池具有较好的充放电性能.     

聚（1-乙烯基-3-乙酸烷基酯咪唑）阳离子／P（MMA．VAc）聚合物电解质

合成了一系列由聚（1-乙烯基-3-乙酸烷基酯咪唑）阳离子和二（三氟甲基磺酰亚胺）阴离子（TFSI）组成的聚离子液体并进行了表征．热重分析（TGA）和电导率分析表明,在聚（甲基丙烯酸甲酯,醋酸乙烯酯）（P（MMA—VAc））基体中掺杂聚离子液体后,体系的热稳定性和离子电导率均大为改善,红外光谱（FT—IR）、示差扫描量热分析（DSC）、X射线衍射（XRD）和扫描电子显微镜（SEM）等测试结果亦可佐证．讨论了离子液体的结构以及不同种锂盐（LiC104,LiBF4,LiTFSI）对电解质性能的影响．由PIL／P（MMA—VAc）／LiTFSI组成的共混电解质膜,在可见光下透过率≥90％,可作为离子导电材料用于电致变色器件（ECD）,显示了其优良的电化学性能．     

添加剂对离子液体凝胶聚合物电解质电化学性能的影响

本文采用1-乙基-3-甲基咪唑六氟磷酸盐(EMIPF₆)、六氟磷酸锂(LiPF₆)和偏氟乙烯-六氟丙烯共聚物(P(VdF-HFP))为原料制得P(VdF-HFP)-EMIPF₆-LiPF₆体系离子液体凝胶聚合物电解质,选取碳酸甲乙酯(EMC)、碳酸二甲酯(DMC)、碳酸二乙酯(DEC)以及碳酸乙烯酯(EC)和碳酸丙烯酯(PC)混合物(EC-PC)作为离子液体凝胶聚合物电解质的添加剂,分别研究了它们对聚合物电解质膜电化学性能的影响。结果表明：加入EC-PC的P(VdF-HFP)-EMIPF₆-LiPF₆电解质膜的电化学窗口达到4.6 V,锂离子迁移数为0.44,30 ℃时离子电导率为1.65 mS·cm^-1;而DEC、DMC、EMC对电解质膜的电化学稳定性、锂离子迁移数存在不良的影响,对离子电导率的提高不明显。研究了正极材料LiCoO₂在P(VdF-HFP)-EMIPF₆-LiPF₆+EC-PC电解质中的充放电循环性能,其首次放电比容量达到116.5 mAh·g^-1,充放电20次后,电池容量没有明显衰减。     

PEO-LiClO4-ZSM5复合聚合物电解质 I. 电化学研究

首次以“择形”分子筛ZSM5为填料, 通过溶液浇铸法制得PEO-LiClO₄-ZSM5全固态复合聚合物电解质(CPE)膜. 交流阻抗实验表明ZSM5的引入可以显著地提高CPE的离子电导率. 利用交流阻抗-稳态电流相结合的方法对CPE的锂离子迁移数进行了测定, 结果表明掺入ZSM5后锂离子迁移数明显升高. ZSM5的含量为10%时, CPE同时具有最高离子电导率1.4×10^－5 S•cm^－1(25 ℃)和最大锂离子迁移数0.353. PEO-LiClO₄-ZSM5/Li电极界面稳定性实验表明PEO-LiClO₄-ZSM5复合聚合物电解质在全固态锂离子电池领域具有良好的应用前景.     

PEO-LiClO4-ZSM5复合聚合物电解质 I. 电化学研究

首次以“择形”分子筛ZSM5为填料, 通过溶液浇铸法制得PEO-LiClO₄-ZSM5全固态复合聚合物电解质(CPE)膜. 交流阻抗实验表明ZSM5的引入可以显著地提高CPE的离子电导率. 利用交流阻抗-稳态电流相结合的方法对CPE的锂离子迁移数进行了测定, 结果表明掺入ZSM5后锂离子迁移数明显升高. ZSM5的含量为10%时, CPE同时具有最高离子电导率1.4×10^－5 S•cm^－1(25 ℃)和最大锂离子迁移数0.353. PEO-LiClO₄-ZSM5/Li电极界面稳定性实验表明PEO-LiClO₄-ZSM5复合聚合物电解质在全固态锂离子电池领域具有良好的应用前景.     

MMA/MAh共聚物的合成及其凝胶聚合物电解质性能

从聚甲基丙烯酸甲酯型凝胶聚合物电解质存在的问题出发,设计制备一种甲基丙烯酸甲酯/共聚马来酸酐型凝胶聚合物电解质.采用溶液聚合法,以偶氮二异丁腈(AIBN)为引发剂,甲基丙烯酸甲酯(MMA)、顺丁烯二酸酐(MAh)为单体,其MMA与MAh单体摩尔配比为1∶1,合成了P(MMA-co-MAh)共聚物;采用凝胶色谱(GPC)、傅立叶红外光谱(FTIR)、核磁共振(MNR)、示差扫描量热法(DSC)、热失重分析(TGA)、X-射线衍射分析(XRD)对所合成共聚物的结构进行了表征.结果表明,合成的共聚物为无规非晶型聚合物,其数均分子量Mn为6.40×104,共聚物中MMA与MAh链段摩尔比大约为8∶1,热分解温度为300℃,玻璃化转变温度(Tg)为121.3℃.以P(MMA-co-MAh)共聚物为树脂基体,环状碳酸1,2-丙二酯(PC)为增塑剂,LiClO4为电解质盐,制备了凝胶聚合物电解质(GPE),当共聚物含量为45 wt%时,GPE具有好的成膜性,其室温离子电导率为3.0×10-5S/cm.     

STUDY ON THE PREPARATION AND PERFORMANCES OF P(VAc-MMA) POLYMER ELECTROLYTES FOR LITHIUM ION BATTERY

A random copolymer P(VAc-MMA)was synthesized via seeded emulsion copolymerization with vinyl acetate (VAc)and methyl methacrylate(MMA)as monomers,and the polymer electrolytes comprising blend of corresponding copolymer P(VAc-MMA)as a host polymer and LiClO_4 as a dopant were prepared by solution casting technique. Performances of the synthesized copolymer and prepared polymer membrane and electrolyte were studied by FTIR,XRD, TG,DSC,mechanical testing and AC impedance.According to the study of FTIR and D...     

Evaluating the electrochemical properties of PEO‐based nanofibrous electrolytes incorporated with TiO2 nanofiller applicable in lithium‐ion batteries

In the present work, nanofibrous composite polymer electrolytes consist of polyethylene oxide (PEO), ethylene carbonate (EC), propylene carbonate (PC), lithium perchlorate (LiClO₄), and titanium dioxide (TiO₂) were designed using response surface method (RSM) and synthesized via an electrospinning process. Morphological properties of the as‐prepared electrolytes were studied using SEM. FTIR spectroscopy was conducted to investigate the interaction between the components of the composites. The highest room temperature ionic conductivity of 0.085 mS.cm^?1 was obtained with incorporation of 0.175 wt. % TiO₂ filler into the plasticized nanofibrous electrolyte by EC. Moreover, the optimum structure was compared with a film polymeric electrolyte prepared using a film casting method. Despite more amorphous structure of the film electrolyte, the nanofibrous electrolyte showed superior ion conductivity possibly due to the highly porous structure of the nanofibrous membranes. Furthermore, the mechanical properties illustrated slight deterioration with incorporation of the TiO₂ nanoparticles into the electrospun electrolytes. This investigation indicated the great potential of the electrospun structures as all‐solid‐state polymeric electrolytes applicable in lithium ion batteries.     

Solid polymer electrolytes III: Preparation,characterization, and ionic conductivity of new gelled polymer electrolytes based on segmented,perfluoropolyether‐modified polyurethane

New segmented polyurethanes with perfluoropolyether (PFPE) and poly(ethylene oxide) blocks were synthesized from a fluorinated macrodiol mixed with poly(ethylene glycol) (PEG) in different ratios as a soft segment, 2,4‐toluene diisocyanate as a hard segment, and ethylene glycol as a chain extender. Fourier transform infrared, NMR, and thermal analysis [differential scanning calorimetry and thermogravimetric analysis (TGA)] were used to characterize the structures of these copolymers. The copolymer films were immersed in a liquid electrolyte (1 M LiClO₄/propylene carbonate) to form gel‐type electrolytes. The ionic conductivities of these polymer electrolytes were investigated through changes in the copolymer composition and content of the liquid electrolyte. The relative molar ratio of PFPE and PEG in the copolymer played an important role in the conductivity and the capacity to retain the liquid electrolyte solution. The copolymer with a 50/50 PFPE/PEG ratio, having the lowest decomposition temperature shown by TGA, exhibited the highest ionic conductivity and lowest activation energy for ion transportation. The conductivities of these systems were about 10^?3 S cm^?1 at room temperature and 10^?2 S cm^?1 at 70 °C; the films immersed in the liquid electrolyte with an increase of 70 wt % were homogenous with good mechanical properties. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 486–495, 2002; DOI 10.1002/pola.10119     

Effect of ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide on the properties of poly(glycidyl methacrylate) based solid polymer electrolytes

A free standing polymer electrolytes films, containing poly(glycidyl methacrylate) (PGMA) as the polymer host, lithium perchlorate (LiClO₄), and ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide [Bmim][TFSI] as a plasticizer was successfully prepared via the solution casting method. The XRD analysis revealed the amorphous nature of the electrolyte. ATR-FTIR and thermal studies confirmed the interaction and complexation between the polymer host and the ionic liquid. The maximum ionic conductivity of the solid polymer electrolyte was found at 2.56 × 10^–5 S cm^–1 by the addition of 60 wt % [Bmim][TFSI] at room temperature and increased up to 3.19 × 10^–4 S cm^–1 at 373 K, as well as exhibited a transition of temperature dependence of conductivity: Arrhenius-like behavior at low and high temperatures.     

Synthesis and properties of all solid polymer electrolytes based on poly(vinyl acetate‐co‐acetyl ethylene oxide acrylate)

Poly(acetyl ethylene oxide acrylate‐co‐vinyl acetate) (P(AEOA‐VAc)) was synthesized and used as a host for lithium perchlorate to prepare an all solid polymer electrolyte. Introduction of carbonyl groups into the copolymer increased ionic conductivity. All solid polymer electrolytes based on P(AEOA‐VAc) at 14.3 wt% VAc with 12wt% LiClO₄ showed conductivity as high as 1.2 × 10^?4 S cm^?1 at room temperature. The temperature dependence of the ionic conductivity followed the VTF behavior, indicating that the ion transport was related to segmental movement of the polymer. FTIR was used to investigate the effect of the carbonyl group on ionic conductivity. The interaction between the lithium salt and carbonyl groups accelerated the dissociation of the lithium salt and thus resulted in a maximum ionic conductivity at a salt concentration higher than pure PAEO‐salts system. Copyright © 2010 John Wiley & Sons, Ltd.     

Lithium garnet based free-standing solid polymer composite membrane for rechargeable lithium battery

Electrolytes with high lithium-ion conductivity, better mechanical strength and large electrochemical window are essential for the realization of high-energy density lithium batteries. Polymer electrolytes are gaining interest due to their inherent flexibility and nonflammability over conventional liquid electrolytes. In this work, lithium garnet composite polymer electrolyte membrane (GCPEM) consisting of large molecular weight (W_avg ~?5?×?10⁶) polyethylene oxide (PEO) complexed with lithium perchlorate (LiClO₄) and lithium garnet oxide Li_6.28Al_0.24La₃Zr₂O₁₂ (Al-LLZO) is prepared by solution-casting method. Significant improvement in Li⁺ conductivity for Al-LLZO containing GCPEM is observed compared with the Al-LLZO free polymer membrane. Maximized room temperature (30 °C) Li⁺ conductivity of 4.40?×?10^?4 S cm^?1 and wide electrochemical window (4.5 V) is observed for PEO₈/LiClO₄?+?20 wt% Al-LLZO (GCPEM-20) membrane. The fabricated cell with LiCoO₂ as cathode, metallic lithium as anode and GCPEM-20 as electrolyte membrane delivers an initial charge/discharge capacity of 146 mAh g^?1/142 mAh g^?1 at 25 °C with 0.06 C-rate.     

ETHYLENE OXIDE-ETHYLENE TEREPHTHALATE SEGMENTED COPOLYMER SOLID ELECTROLYTE8

 A series of ethylene oxide-ethylene terephthalate segmented copolymers (EOET) weresynthesized and complexed with LiClO₄ to form some new polymer electrolytes. The EOET-LiClO₄ electrolytes exhibit not only high ionic conductivity, but also good mechanical strengthand toughness. The EOET 3400--25--LiClO₄ complex possesses the highest conductivity (4. 65×10^-5s·cm^-1 at room temperature when the ratio [Li⁺]/[EO] equals 1/16. The structures of these electrolytes were examined with FTIR analysis, X-ray diffraction and DSC thermograms,and the results of high ionic conductivity of the segmented copolymers were discussed.     

Investigations on poly(methyl methacrylate)-poly(ethylene oxide) hybrid polymer electrolytes with dioctyl phthalate, dimethyl phthalate and diethyl phthalate as plasticizers

Plasticizers can be used to change the mechanical and electrical properties of polymer electrolytes by reducing the degree of crystallinity and lowering the glass transition temperature. The transport properties of gel-type ionic conducting membranes consisting of poly(ethylene oxide) (PEO), poly(methyl methacrylate) (PMMA), LiClO₄ and dioctyl phthalate, diethyl phthalate or dimethyl phthalate (DMP) are studied. The polymer films are characterized by X-ray diffraction, Fourier transform infrared and impedance spectroscopic studies. It is found that the addition of DMP as the plasticizer in the PEO-PMMA-LiClO₄ polymer complex favours an enhancement in ionic conductivity. The maximum conductivity value obtained for the solid polymer electrolyte film at 305 K is 3.529×10^{– 4} S cm^–1. Electronic Publication