PEO/LiClO_4纳米SiO_2复合聚合物电解质的电化学研究

将实验室制备的纳米二氧化硅和市售纳米二氧化硅粉末与PEO LiClO4复合 ,制得了复合PEO电解质 .它们的室温离子电导率可比未复合的PEO电解质提高 1～ 2个数量级 ,最高可以达到 1 2 4× 10 - 5S cm .离子电导率的提高有两方面的原因 :一是无机二氧化硅粉末的加入抑制了PEO的结晶 ,是二氧化硅粉末和聚合物电解质之间形成的界面对电导率的提高也有一定的作用 .在进一步加入PC EC(碳酸丙烯酯 碳酸乙烯酯 )混合增塑剂后制得的复合凝胶PEO电解质 ,可使室温离子电导率再提高 2个数量 ,达到 2× 10 - 3 S cm .用这种复合凝胶PEO电解质组装了Li|compositegelelectrolyte|Li半电池 ,并测量了该半电池的交流阻抗谱图随组装后保持时间的变化 ,实验观察到在保持时间为 144h以内钝化膜的交流阻抗迅速增大 ,但在随后的时间内逐渐趋于平稳 ,表明二氧化硅粉末的加入可以有效地抑制钝化膜的生长     

A new composite polymer electrolyte based on poly(ethyleneoxide)/ polysiloxane/BMImTFSI/organomontmorillonite

Composite polymer electrolytes based on poly(ethylene oxide)-polysiloxane/l-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide/organomontmorillonite(PEO-PDMS/1L/OMMT) were prepared and characterized.Addition of both an ionic liquid and OMMT to the polymer base of PEO-PDMS resulted in an increase in ionic conductivity.At room temperature,the ionic conductivity of sample PPB100-OMMT4 was 2.19×10~3 S/cm.The composite polymer electrolyte also exhibited high thermal and electrochemical stability and may potentially be applied in lithium batteries.     

Safety-enhanced Polymer Electrolytes with High Ambient-temperature Lithium-ion Conductivity Based on ABA Triblock Copolymers

Liquid electrolytes used in lithium-ion batteries suffer from leakage,flammability,and lithium dendrites,making polymer electrolyte a potential alternative.Herein,a series of ABA triblock copolymers(ABA-x)containing a mesogen-jacketed liquid crystalline polymer(MJLCP)with a polynorbornene backbone as segment A and a second polynorbornene-based polymer having poly(ethylene oxide)(PEO)side chains as segment B were synthesized through tandem ring-opening metathesis polymerizations.The block copolymers can self-assemble into ordered morphologies at 200℃.After doping of lithium salts and ionic liquid(IL),ABA-x self-assembles into cylindrical structures.The MJLCP segments with a high glass transition temperature and a stable liquid crystalline phase serve as physical crosslinking points,which significantly improve the mechanical performance of the polymer electrolytes.The ionic conductivity of ABA-x/lithium salt/IL is as high as 10-3 S·cm-1 at ambient temperature owing to the high IL uptake and the continuous phase of conducting PEO domains.The relationship between ionic conductivity and temperature fits the Vogel-Tamman-Fulcher(VTF)equation.In addition,the electrolyte films are flame retardant owing to the addition of IL.The polymer electrolytes with good safety and high ambient-temperature ionic conductivity developed in this work are potentially useful in solid lithium-ion batteries.     

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.     

Conductive networked polymer gel electrolytes composed of poly(meth)acrylate,lithium salt,and ionic liquid

Self‐standing films of (meth)acrylate‐based polymer gel electrolytes with high ionic liquid content (80 wt %) were prepared by in situ thermally or photo induced radical copolymerization of mono‐functional and di‐functional (meth)acrylates in an ionic liquid in the presence/absence of a lithium salt. Their ionic conductivity, thermal property, mechanical property, and flammability were examined. 1‐Ethyl‐3‐methylimidazolium bis(trifluoromethanesulfonyl)imide (EMImTFSI) or 1‐ethyl‐3‐methylimidazolium bis(fluorosulfonyl)imide (EMImFSI) was used as the ionic liquid, and lithium bis(trifluoromethanesulfonyl)imide LiTFSI was used as the lithium salt. The obtained films were semitransparent and flexible with good to moderate thermal stability and mechanical strength with high ionic conductivity. The EMImFSI‐containing gel electrolytes showed higher ionic conductivity than the corresponding EMImTFSI‐containing gel electrolytes. The ionic conductivity in the acrylate‐based gel electrolytes was slightly increased by addition of lithium salt, while that in the corresponding methacrylate‐based electrolytes was decreased significantly. The flame test showed the ionic liquid containing networked polymer gel electrolytes to have low if any flammability and was therefore confirmed to be highly safe. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

交联PEO嵌段共聚物固体电解质的制备及导电性研究

利用低分子聚乙二醇 (PEG ,Mn=6 0 0 )与CH2 Cl2 在碱性条件下通过Williamson反应生成氧亚甲基连接的聚氧化乙烯嵌段聚合物 .1 H NMR表明 ,其分子平均组成以 [CH2 O(CH2 CH2 O) 1 3]为重复单元结构 .适量的2 ,4 二异氰酸甲苯酯 (TDI)与聚合物 锂盐电解质形成交联网络结构 ,具有较好的成膜性能、力学性能与热稳定性能 .在测试温度范围内 ,电导率与温度的关系很好的符合Arrhenius关系式 (σ =Ae-Ea RT) .锂盐浓度不同 ,Arrhenius曲线有一个或两个活化能 (Ea)值出现 .该聚合物掺混LiN(CF3SO2 ) 2 形成的固体电解质具有良好的导电性 ,在EO Li =2 5∶1(摩尔比 )时 ,室温下σ =1 12× 10 - 5S cm ,分解电压可达 5 0V .     

Polymer electrolyte for lithium batteries based on photochemically crosslinked poly(ethylene oxide) and ionic liquid

Polymer/ionic liquid composites were investigated as solvent-free electrolytes for lithium batteries. Ternary electrolytes based upon poly(ethylene oxide), an ionic liquid and a conducting salt were UV crosslinked with benzophenone as the photoinitiator. Crosslinking leads to an increase in mechanical stability of the PEO composites. This straight-forward process provides a way to increase the content of ionic liquid and thus to raise ionic conductivity without loss of mechanical stability. Impedance measurements showed that the ionic conductivity of the composites is not affected by the UV curing process. Moreover, the UV curing process causes a decrease in the degree of crystallinity in the PEO composites which contributes to an increase in ionic conductivity. The present work is related to safety issues of lithium batteries.     

相态结构对聚氧化乙烯/丁二腈/高氯酸锂复合电解质室温电导率的影响

采用聚氧化乙烯(PEO)、丁二腈和高氯酸锂(LiClO4)的复合电解质体系, 制备了一系列不同配比的PEO/SN/LiClO4复合电解质, 对其室温电性能和相态结构进行了表征, 并探讨了相态结构对室温电导率的影响.     

Molecular dynamics simulation of polymer electrolytes based on poly(ethylene oxide) and ionic liquids. II. Dynamical properties

Dynamical properties of polymer electrolytes based on poly(ethylene oxide) (PEO) and ionic liquids of 1-alkyl-3-methylimidazolium cations were calculated by molecular dynamics simulations with previously proposed models [L. T. Costa and M. C. Ribeiro, J. Chem. Phys. 124, 184902 (2006)]. The effect of changing the ionic liquid concentration, temperature, and the 1-alkyl-chain lengths, [1,3-dimethylimidazolium]PF(6) and [1-butyl-3-methylimidazolium]PF(6) ([dmim]PF(6) and [bmim]PF(6)), was investigated. Cation diffusion coefficient is higher than those of anion and oxygen atoms of PEO chains. Ionic mobility in PEO[bmim]PF(6) is higher than in PEO[dmim]PF(6), so that the ionic conductivity kappa of the former is approximately ten times larger than the latter. The ratio between kappa and its estimate from the Nernst-Einstein equation kappa/kappa(NE), which is inversely proportional to the strength of ion pairs, is higher in ionic liquid polymer electrolytes than in polymer electrolytes based on inorganic salts with Li(+) cations. Calculated time correlation functions corroborate previous evidence from the analysis of equilibrium structure that the ion pairs in ionic liquid polymer electrolytes are relatively weak. Structural relaxation at distinct spatial scales is revealed by the calculation of the intermediate scattering function at different wavevectors. These data are reproduced with stretched exponential functions, so that temperature and wavevector dependences of best fit parameters can be compared with corresponding results for polymer electrolytes containing simpler ions.     

Studies on poly(vinyl pyrrolidone) based solid polymer blend electrolytes complexed with various lithium salts

Solid polymer electrolytes (SPEs) with high ionic conductivity and acceptable mechanical properties are of particular interest for increasing the performance of batteries. In the present work, SPEs based on poly(ethylene oxide)/poly (vinyl pyrrolidone) (PEO/PVP) with various lithium salts were prepared by solvent casting technique. The amorphous nature of the polymer-salt complex was studied by X-ray diffraction analysis. The complexation of the prepared electrolytes was confirmed by Fourier transform infrared analysis. Ionic conductivity as a function of frequency was studied at various temperatures in the range of 303–353 K. The maximum ionic conductivity value was found to be 1.08 × 10^?5 S/cm for the film containing lithium bis trifluoromethane sulfonoimide (LiN[CF₃SO₂]₂) at room temperature and the temperature dependent ionic conductivity values seem to obey Vogel-Tamman-Fulcher relation. Thermogravimetry was used to ascertain the thermal stability of the electrolytes. Photoluminescence measurements demonstrated that the sample having maximum ionic conductivity shows the minimum luminescence intensity. Ultra violet-visible analysis reveals that the values of the band gap energies were changed with the addition of various lithium salts. Porosity of the sample containing lithium bis trifluoromethane sulfonoimide (LiN[CF₃SO₂]₂) was studied by Atomic force microscope.     

Review on gel polymer electrolytes for lithium batteries

This paper reviews the state-of-art of polymer electrolytes in view of their electrochemical and physical properties for the applications in lithium batteries. This review mainly encompasses on five polymer hosts namely poly(ethylene oxide) (PEO), poly(acrylonitrile) (PAN), poly(methyl methacrylate) (PMMA), poly(vinylidene fluoride) (PVdF) and poly(vinylidene fluoride-hexafluoro propylene) (PVdF-HFP) as electrolytes. Also the ionic conductivity, morphology, porosity and cycling behavior of PVdF-HFP membranes prepared by phase inversion technique with different non-solvents have been presented. The cycling behavior of LiMn₂O₄/polymer electrolyte (PE)/Li cells is also described.     

Electro chemical properties of porous PVdF-HFP membranes prepared with different nonsolvents

Porous poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) membranes were prepared by solvent–nonsolvent evaporation technique. Morphology and porosity of the membranes were varied with different nonsolvents and had an effect on electrochemical properties. The porous membranes were functionalized with different liquid electrolyte solutions such as p-toluene sulfonic acid/phosphoric acid/sulfuric acid. Maximum electrolyte uptake and minimal electrolyte leakage were tailored by the optimized porosity of the membranes. Thermal behavior obtained in this study ensures the complete evaporation of nonsolvents and ensures its thermal stability. The pTSA-activated PVdF-HFP/THF membrane exhibited high ionic conductivity of about 27.27 mS/cm and a lower methanol permeability in the range of 9.7 × 10⁻⁸ cm²/s. High compatibility between pTSA solution and porous PVdF-HFP polymer electrolyte membrane enhances its electro chemical behavior than that of conventional liquid electrolytes.     

Preparation and characterization of a mixing soft-segment waterborne polyurethane polymer electrolyte

The mixing soft-segment WPU(waterborne polyurethane)polymer electrolytes were synthesized by using PEO(poly(ethylene oxide))and PDMS(polydimethylsiloxane)as the soft segments.These polymer electrolytes exhibit good thermal and electrochemical stability.The conductivity of the gel polymer electrolyte is 2.52 x 10~(-3)S/cm at 25℃with the LiTFSI/(DMC+EC) content of 130%.     

Cross-linking copolymers of acrylates’ gel electrolytes with high conductivity for lithium-ion batteries

The cross-linking gel copolymer electrolytes containing alkyl acrylates, triethylene glycol dimethacrylate, and liquid electrolyte were prepared by in situ thermal polymerization. The gel polymer electrolytes containing 15 wt% polymer content and 85 wt% liquid electrolyte content with sufficient mechanical strength showed the high ionic conductivity around 5?×?10^?3 Scm^?1 at room temperature. The gel electrolytes containing different polymer matrices were prepared, and their physical observation and conductivity were discussed carefully. The cross-linking copolymer gel electrolytes of alkyl acrylates with other monomers were designed and synthesized. The results showed that copolymerization can improve the mechanical properties and ionic conductivities of the gel electrolytes. The polymer matrices of gels had excellent thermal stability and electrochemical stability. The scanning electron microscope analysis showed the gel electrolyte was the homogeneous structure, and the cross-linking polymer host was the porous three-dimensional network structure, which demonstrated the high conductivity of the gel electrolytes. The gel polymer Li-ion battery was prepared by this in situ thermal polymerization. The cell exhibited high charge-discharge efficiency at 0.1 C. The results of LiFePO4-PEA-Li cell and graphite-PEA-Li cell showed that gel polymer electrolytes have good compatibility with the battery electrodes materials.     

High ionic conductivity P(VDF-TrFE)/PEO blended polymer electrolytes for solid electrochromic devices

Solid polymer electrolytes with excellent ionic conductivity (above 10(-4) S cm(-1)), which result in high optical modulation for solid electrochromic (EC) devices are presented. The combination of a polar host matrix poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) and a solid plasticized of a low molecular weight poly(ethylene oxide) (PEO) (M(w)≤ 20,000) blended polymer electrolyte serves to enhance both the dissolution of lithium salt and the ionic transport. Calorimetric measurement shows a reduced crystallization due to a better intermixing of the polymers with small molecular weight PEO. Vibrational spectroscopy identifies the presence of free ions and ion pairs in the electrolytes with PEO of M(w)≤ 8000. The ionic dissolution is improved using PEO as a plasticizer when compared to liquid propylene carbonate, evidently shown in the transference number analysis. Ionic transport follows the Arrhenius equation with a low activation energy (0.16-0.2 eV), leading to high ionic conductivities. Solid electrochromic devices fabricated with the blended P(VDF-TrFE)/PEO electrolytes and polyaniline show good spectroelectrochemical performance in the visible (300-800 nm) and near-infrared (0.9-2.4 μm) regions with a modulation up to 60% and fast switching speed of below 20 seconds. The successful introduction of the solid polymer electrolytes with its best harnessed qualities helps to expedite the application of various electrochemical devices.     

Synthesis and characterization of mixing soft-segmented waterborne polyurethane polymer electrolyte with room temperature ionic liquid

Composite polymer electrolytes based on mixing soft-segment waterborne polyurethane(WPU)and 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide(BMImTFSI)have been prepared and characterized.The addition of BMImTFSI results in an increase of the ionic conductivity.At high BMImTFSI concentration(BMImTFSI/WPU=3 in weight ratio),the ionic conductivity reaches 4.27×10~(-3)S/cm at 30℃.These composite polymer electrolytes exhibit good thermal and electrochemical stability,which are high enough to be...     

Ion conducting properties of poly(ethylene oxide)-based electrolytes incorporating amorphous silica attached with imidazolium salts

Poly(ethylene oxide) (PEO)-based polymer electrolytes containing amorphous silica attached ionic liquid (IL) were studied in order to improve electrochemical and interfacial properties. An imidazolium salt such as IL was attached to modified ceramic fillers. The modified ceramic fillers were amorphous silica with the immobilized 1-methyl-3-propyl-imidazolium bromide (MPIm-AS). PEO-based polymer electrolytes were prepared by using the solution casting technique. In order to investigate the ionic conductivity, studies on the modified filler addition effects on the ion-conducting behavior of polymer electrolytes having specific amounts of MPIm-AS were carried out. The addition of MPIm-AS in polymer electrolytes has resulted in higher ionic conductivity at room temperature. The structure, crystallinity, and morphology of the solid polymer electrolytes were evaluated using X-ray diffraction, differential scanning calorimetry, and scanning electron microscope measurement. The ionic conductivity was measured by an AC impedance method. The enhanced conductivity was dependent on the decreased crystallinity and the changed morphologies of composites.     

Highly ion conductive poly(ethylene oxide)-based solid polymer electrolytes from hydrogen bonding layer-by-layer assembly

We report the development of a solid polymer electrolyte film from hydrogen bonding layer-by-layer (LBL) assembly that outperforms previously reported LBL assembled films and approaches battery integration capability. Films were fabricated by alternating deposition of poly(ethylene oxide) (PEO) and poly(acrylic acid) (PAA) layers from aqueous solutions. Film quality benefits from increasing PEO molecular weight even into the 10(6) range due to the intrinsically low PEO/PAA cross-link density. Assembly is disrupted at pH near the PAA ionization onset, and a potential mechanism for modulating PEO:PAA ratio within assembled films by manipulating pH is discussed. Ionic conductivity of 5 x 10(-5) S/cm is achievable after short exposure to 100% relative humidity (RH) for plasticization. Adding free ions by exposing PEO/ PAA films to lithium salt solutions enhanced conductivity to greater than 10(-5) S/cm at only 52% RH and tentatively greater than 10(-4) S/cm at 100% RH. The excellent stability of PEO/PAA films even when exposed to 1.0 M salt solutions led to an exploration of LBL assembly with added electrolyte present in the adsorption step. Fortuitously, the modulation of PEO/PAA assembly by ionic strength is analogous to that of electrostatic LBL assembly and can be attributed to electrolyte interactions with PEO and PAA. Dry ionic conductivity was enhanced in films assembled in the presence of salt as compared to films that were merely exposed to salt after assembly, implying different morphologies. These results reveal clear directions for the evolution of these promising solid polymer electrolytes into elements appropriate for electrochemical power storage and generation applications.     

Li1.5Al0.5Ge1.5(PO4)3基固体复合电解质的制备及锂离子导电行为

将聚氧化乙烯(PEO)和二(三氟甲基磺酰)亚胺锂(LiTFSI)混合(固定EO/Li摩尔比为13)后, 采用溶液浇注法制备了一系列不同Li_1.5Al_0.5Ge_1.5(PO₄)₃(LAGP)与PEO质量比的LAGP-PEO(LiTFSI)固体复合电解质体系. 结合电化学阻抗法、 表面形貌表征以及与惰性陶瓷填料(SiO₂, Al₂O₃) 性能的对比分析, 探讨了LAGP在固体复合电解质中的作用机理以及锂离子的导电行为. 结果表明, 在以LAGP为主相的固体复合电解质中, PEO主要处于无定形态, 整个体系主要为PEO与LiTFSI的络合相、 LAGP与PEO(LiTFSI)相互作用形成的过渡相和LAGP晶相. 其中LAGP作为主要的导电基体不仅起到降低PEO结晶度、 改善两相导电界面的作用; 同时自身也可以作为离子传输的通道, 降低锂离子迁移的活化能, 从而使离子电导率得到提高. 当LAGP与PEO的质量比为6:4时, 固体复合电解质的成膜性能最好, 离子电导率最高, 在30 ℃时为2.57×10^-5 S/cm, 接近LAGP的水平, 电化学稳定窗口超过5 V.     

Plasticized polymer electrolyte membranes based on PEO/PVdF-HFP for use as an effective electrolyte in lithium-ion batteries

Plasticized polymer electrolytes were prepared using poly(ethylene oxide)(PEO)/poly(vinylidene fluoridehexafluoro propylene)(PVd F-HFP) with lithium perchlorate(Li Cl O4) and different plasticizers. XRD and FTIR spectroscopic techniques were used to characterize the structure and the complexation of plasticizer with the host polymer matrix. The role of interaction between polymer hosts and plasticizer on conductivity is discussed using the results of alternating current(a.c.) impedance studies. TG-DTA and SEM were used for thermal and physical characterizations. Maximum ionic conductivity(3.26 × 10~(-4) S·cm~(-1)) has been observed for ethylene carbonate(EC)-based polymer electrolytes. Electrochemical performance of the plasticized polymer electrolyte is evaluated in LiFePO_4/plasticized polymer electrolytes(PPEs)/Li coin cell. Good performance with low capacity fading on charge discharge cycling is demonstrated.