纳米阻燃氢氧化镁/聚氧化乙烯复合聚合物电解质

合成了纳米氢氧化镁作为聚氧化乙烯(PEO)基聚合物电解质的增塑剂和阻燃剂,并对其进行X射线衍射(XRD)、透射电子显微镜(TEM)和热重(TG)分析研究.制得的氢氧化镁为片状六方晶体,尺寸在50-80nm之间,纳米氢氧化镁在340℃时开始热分解.对纳米氢氧化镁/PEO复合聚合物电解质的电化学研究结果显示:纳米氢氧化镁/PEO复合聚合物电解质的离子电导率随着添加纳米氢氧化镁的质量分数的增加先增大后减小,其在5%-10%之间时,复合聚合物电解质的离子电导率达到最大值.纳米氢氧化镁的添加使复合聚合物电解质的阳极氧化电位有一定程度的提高,纳米氢氧化镁具有改善PEO阳极抗氧化能力的作用.     

增塑聚合物电解质电化学性能

以GBL/EC复配体系为增塑剂, PVDF HFP和PMMA为聚合物基体制备胶态聚合物电解质. 研究聚合物电解质的离子传输特性和电化学稳定性. 实验表明,室温离子电导率达到 1. 2mS·cm-1, 电化学稳定窗口在 4. 5V以上. 以GBL/EC增塑聚合物电解质与表面经修饰的锂金属电极组成锂金属聚合物电池,其电极稳定性较好,充放电循环寿命得到很大的提高.     

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。     

聚合物电解质中增塑剂的研究进展

聚合物电解质在锂离子电池中有很好的应用前景,已成为当前锂离子电池研究领域的热点之一.但由于其室温电导率低,在实际应用中受到诸多限制.通常采用在聚合物电解质中添加适当比例的增塑剂以提高其离子电导率的方法来弥补此缺陷.本文综述了聚合物电解质中增塑剂的增塑原理、增塑剂的种类以及电解质中新型增埋剂的研究状况.     

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     

固态聚合物电解质的锂离子传导机理与研究进展

锂离子电池(lithiumionbatteries,LIBs)在储能领域已取得了巨大的成功.然而,商用LIBs含有高挥发性易燃有机电解液,使其存在严重的安全隐患.固态聚合物电解质具有解决相应安全性问题的潜力,有望成为下一代高安全性全固态LIBs的电解质材料.然而,固态聚合物电解质存在离子电导率不高等问题,限制了其在固态LIBs中的实际应用.研究者们为了提高该类电解质的离子电导率、锂离子迁移数等综合电化学性能,已在寻找新锂盐、对聚合物进行改性以及向聚合物电解质中添加填料等方面进行了较多的研究.本文简要概述了固态聚合物电解质的锂离子传导机理以及在提高固态聚合物电解质综合电化学性能方面的研究进展.     

表面改性纳米SiO2复合聚合物电解质的制备及性能

通过化学方法将具有增塑效果的环状碳酸酯基团引入纳米SiO2表面,并用FTIR与TGA对改性纳米SiO2进行了表征.将改性纳米SiO2添加到以聚氧化乙烯(PEO)为基体的聚合物电解质中,制备了复合聚合物电解质.通过DSC和交流阻抗等方法对该聚合物电解质膜的热力学和电化学性能进行了研究.结果表明,掺杂改性纳米SiO2的聚合物电解质具有更高的离子电导率,室温最高离子电导率可达到1.84×10-5 S/cm;具有较高的锂离子迁移数,最高可达到0.49,且具有更好的界面稳定性.     

介孔材料SBA-15改性的复合凝胶聚合物电解质的制备及性能

以聚(甲基丙烯酸甲酯-聚乙二醇二甲基丙烯酸酯)(P(MMA-PEGDMA))共聚物为基体,介孔硅分子筛SBA-15为无机填料制备了复合凝胶聚合物电解质.采用原子力显微镜(AFM)、热重分析(TG)和交流阻抗(AC)等技术对其形貌、热稳定性及电化学性能进行了研究.结果表明:无机填料SBA-15与聚合物基体有较好的相容性;SBA-15的加入改善了聚合物电解质的热稳定性,提高了离子电导率,当W(SBA-15)=0.03时,离子电导率达最大值3.68×lO-3S/cm;并且掺杂SBA-15后,聚合物电解质的电化学稳定性得到了提高,其电化学稳定窗口为4.9V(vs Li /Li),可满足高性能锂离子电池的要求.     

纳米Al2O3填充的PVDF-HFP复合电解质的导电性

用真空蒸发法制备了不同配方的PVDF-HFP复合电解质膜,通过交流阻抗测试,优选出机械和电化学性能较好的PVDF-HFP复合电解质的工艺参数,m(纳米Al₂O₃)∶m(增塑剂DBP)∶m(PVDF-HFP)=10∶45∶45.用丙酮抽提制得的PVDF-HFP聚合物膜中的增塑剂,再于1mol/LLiPF₆/DEC-EC(体积比1∶1)的液态电解质中浸渍,浸渍后聚合物膜的电导率达到10-3S/cm数量级.     

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.     

PVA碱性凝胶聚合物电解质薄膜电化学稳定性研究

应用溶解—铸膜法制备聚乙烯醇(polyvinylalcohol,PVA)碱性凝胶聚合物电解质(gelpolymerelectrolyte,GPE)薄膜.交流阻抗(EIS)测试表明,随着KOH含量的增加,该薄膜的离子电导率表现为先增大而后减小的变化趋势,当KOH含量为42%(bymass,下同)时,电导率达到最大值,为2.01×10-3S/cm.X射线衍射(XRD)结果表明,当膜中KOH含量大于20%时,晶态的PVA就逐渐转变为非晶态结构.又当KOH含量增加到一定值后,由于体系中未电离的非晶态KOH量的增多而导致离子电导率下降.循环伏安(CV)和拉曼光谱(Raman)结果表明,该薄膜具有很好的电化学稳定性,可应用于碱性二次电池.     

Effect of plasticizers (EC or PC) on the ionic conductivity and thermal properties of the (PEO)9LiTf: Al2O3 nanocomposite polymer electrolyte system

A new plasticized nanocomposite polymer electrolyte based on poly (ethylene oxide) (PEO)-LiTf dispersed with ceramic filler (Al₂O₃) and plasticized with propylene carbonate (PC), ethylene carbonate (EC), and a mixture of EC and PC (EC+PC) have been studied for their ionic conductivity and thermal properties. The incorporation of plasticizers alone will yield polymer electrolytes with enhanced conductivity but with poor mechanical properties. However, mechanical properties can be improved by incorporating ceramic fillers to the plasticized system. Nanocomposite solid polymer electrolyte films (200–600 μm) were prepared by common solvent-casting method. In present work, we have shown the ionic conductivity can be substantially enhanced by using the combined effect of the plasticizers as well as the inert filler. It was revealed that the incorporating 15 wt.% Al₂O₃ filler in to PEO: LiTf polymer electrolyte significantly enhanced the ionic conductivity [σ _RT (max)?=?7.8?×?10^?6 S cm^?1]. It was interesting to observe that the addition of PC, EC, and mixture of EC and PC to the PEO: LiTf: 15 wt.% Al₂O₃ CPE showed further conductivity enhancement. The conductivity enhancement with EC is higher than PC. However, mixture of plasticizer (EC+PC) showed maximum conductivity enhancement in the temperature range interest, giving the value [σ _RT (max)?=?1.2?×?10^?4 S cm^?1]. It is suggested that the addition of PC, EC, or a mixture of EC and PC leads to a lowering of glass transition temperature and increasing the amorphous phase of PEO and the fraction of PEO-Li⁺ complex, corresponding to conductivity enhancement. Al₂O₃ filler would contribute to conductivity enhancement by transient hydrogen bonding of migrating ionic species with O–OH groups at the filler grain surface. The differential scanning calorimetry thermograms points towards the decrease of T _g , crystallite melting temperature, and melting enthalpy of PEO: LiTf: Al₂O₃ CPE after introducing plasticizers. The reduction of crystallinity and the increase in the amorphous phase content of the electrolyte, caused by the filler, also contributes to the observed conductivity enhancement.     

Effects of organophilic clay on the solvent‐maintaining capability,dimensional stability,and electrochemical properties of gel poly(vinylidene fluoride) nanocomposite electrolytes

Four quaternary alkyl ammonium salts were used in an organophilic procedure, performed on montmorillonite clay, and resulted in intercalation in dimethylformamide (DMF) or ethylene carbonate (EC)/propylene carbonate (PC) as a cosolvent between poly(vinylidene fluoride) (PVdF) and the organophilic clay. An examination using X‐ray diffraction revealed that PVdF entered galleries of montmorillonite clay, and it exhibited exfoliation and intercalation phenomena when it was analyzed with transmission electron microscopy. Gel PVdF nanocomposite electrolyte materials were successfully prepared by the addition of the appropriate percentages of DMF or PC/EC as a cosolvent, organophilic clay, and lithium perchlorate to PVdF. The maximum ionic conductivity was 1.03 × 10^?2 S/cm, and the materials exhibited better film formation, solvent‐maintaining capability, and dimensional stability than electrolyte films without added organophilic clays. The results of cyclic voltammetry testing showed that the addition of the organophilic clays significantly enhanced the electrochemical stability of the polymer electrolyte system. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3873–3882, 2002     

燃料电池用聚乙烯醇基碱性聚合物电解质膜的制备及其性能

通过在不同浓度KOH溶液中进行掺杂,制备出了聚乙烯醇(PVA)、聚乙烯醇/聚乙烯吡咯烷酮(PVA/PVP)和聚乙烯醇/聚乙二醇二甲醚(PVA/PEGDE)碱性聚合物电解质膜详细考察了膜的外观形貌、微观结构、热稳定性、离子电导率和化学稳定性等.结果表明,PVA与PVP以及PEGDE具有很好的相容性,所制备的复合膜断面致密...     

On the interaction of carbon electrodes and non conventional electrolytes in high-voltage electrochemical capacitors

This study is essentially based on innovative electrolytes such as the organic salt N-methyl-N-butylpyrrolidinium tetrafluoroborate (Pyr₁₄BF₄) dissolved in propylene carbonate (PC) and the pure ionic liquid (N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr₁₄TFSI) and its solution in PC. Activated carbon cloths were used as self-standing binder-free electrodes. It is found that the presence of impurities in carbon electrodes may lead to electrolyte decomposition and electrode degradation which notably affect the electrochemical double-layer capacitor (EDLC) performance. Such processes greatly depend on the composition of both the electrode and the electrolyte, being much less significant with solvent-containing electrolytes. By raising the operation temperature to 60 °C, the EDLC performance in the ionic liquid Pyr₁₄TFSI is notably improved due to a relevant decrease in the viscosity and increase in ionic conductivity. By contrast, the presence of impurities, e.g., Zn and Al, in the electrodes remarkably reduces the electrolyte stability and a thick layer of decomposition products completely covers the carbon fibers after cycling at high temperature. The ionic liquid in solution maintains the high maximum operative voltage of the net ionic liquid whereas its viscosity and ionic conductivity are close to those of the conventional Et₄NBF₄/PC. Furthermore, the presence of propylene carbonate as solvent prevents to some extent the ionic liquid degradation.     

聚乙烯醇/聚乙烯吡咯烷酮碱性复合膜的制备及其性能

通过在不同浓度KOH溶液中进行掺杂,制备出了聚乙烯醇/聚乙烯吡咯烷酮(PVA/PVP)碱性聚合物电解质膜.详尽考察了膜的组成、微观结构、热稳定性、离子电导率和甲醇吸收率.结果表明,PVA与PVP两者具有较好的相容性,当m(PVA)∶m(PVP)=1∶0.5时,膜断面致密、均匀,未发生大尺度相分离.PVP的混入可以极大提高复合膜的电导率和热稳定性.当m(PVA)∶m(PVP)=1∶1时,复合膜的电导率可达2.01×10-3 S.cm-1.PVA/PVP/KOH膜的甲醇吸收率随温度的升高没有明显变化,100℃时其甲醇吸收率仅为同条件下Nafion 115膜的1/4.这表明该复合膜有望作为一种新型的碱性直接甲醇燃料电池用固体电解质膜且可提高膜的使用温度.     

Alkaline Zn-air and Al-air cells based on novel solid PVA/PAA polymer electrolyte membranes

High ionic conducting solid polymer electrolyte membranes (SPEM) had been successfully prepared from poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA). The solution casting method yielded highly hydrophilic membranes with uniform structure that were suitable for electrochemical applications. The room temperature ionic conductivity of the alkaline PVA/PAA polymer electrolyte membranes was in the range of 0.142–0.301 S cm⁻¹ depending on the composition. The cyclic voltammetry analysis was carried out using Zn|SPEM|Zn and Al|SPEM|Al cells. The analysis results revealed the excellent electrochemical stability of these newly developed alkaline solid PVA/PAA polymer electrolyte membranes. Metal-air fuel cells were also prepared from the alkaline solid PVA/PAA polymer electrolyte membranes. The electrochemical cell performance was evaluated based on Zn-air and Al-air cells at C/10 and C/5 discharge rates. The experimental results exhibited high percent of utilization for metal powders at room temperature. It was up to 90% for Zn-air cell when assembled with PVA:PAA = 10:7.5 polymer electrolyte membrane and discharged at C/10 rate. The power density could be as high as 50 mW cm⁻² at room temperature. However, the cell percent utilization was reduced to 73% with the same composition electrolyte membrane when C/5 discharge rate was tested.     

一种新型有机硅离子液体电解液在超级电容中的应用

设计合成了一种新型有机硅室温离子液体(SiN1IL), 并对其化学结构和电化学窗口进行表征, 通过与具有高介电常数的丙烯碳酸酯(PC)/低粘度的乙腈(AN)匹配组成电解液, 其离子电导率达到商业实际应用的要求(19.6 mS·cm^-1). 对以活性炭(AC)为对称电极的超级电容器的电化学性能测试表明, SiN1IL 基电解液与活性炭有很好的界面相容性, 其高倍率充放电、阻抗性能优于商用四乙基四氟硼酸铵(Et₄NBF₄)/PC 电解液, 在电流密度为1000 mA·g^-1的条件下, 工作电压为2.7 V, 其比电容为108 F·g^-1.     

Characterization of poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) electrolytes complexed with different lithium salts

Poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) gel electrolytes comprising a combination of plasticizers, ethylene carbonate (EC) and propylene carbonate (PC) and lithium salt LiX have been prepared using the solution casting technique in an argon atmosphere. The prepared electrolytes were subjected to ionic conductivity, compatibility with lithium metal anode and thermogravimetric (TG)/differential thermal analysis (DTA). The membranes, which possess lithium salt, LiBF₄ exhibited maximum conductivity and on contrary it undergoes severe passivation with lithium metal. All these membranes are found to be stable thermally about 70 °C.     

溶剂及电解质盐对氧在有机电解液体系中电化学还原的影响

应用线性循环伏安(CV)法研究了氧在几种有机电解液体系中的电化学还原过程.实验表明,氧在四丁基六氟磷酸铵(TBAPF6)/乙腈(MeCN)或TBAPF6/丙烯碳酸酯(PC)电解液中,均首先发生1电子还原生成O2-的过程,但电位回扫还原过程的可逆性却表现出很大差异:在乙腈溶液中反应可逆性较好,CV曲线表现出一对可逆的氧化还原峰,而在丙烯碳酸酯为溶剂的电解液中,氧还原过程可逆性差,不仅初始氧还原电流显著减小,而且表征O2-氧化的电流峰几乎消失.此外,电解质盐对氧还原过程也具有很大影响,在六氟磷酸锂(LiPF6)/乙腈电解液中,氧的还原可逆性较差.