离子液体掺杂凝胶电解质的制备及性能

以N-N二甲基丙烯酰胺(DMAA)和甲基丙烯酰氧基二苯酮(MABP)为单体,利用自由基共聚合制备了聚合物母体材料。将合成的母体材料,离子液体与双(三氟甲烷磺酰)亚胺锂一起混合成均匀溶液,采用简单的溶液铸膜工艺制备成膜,经紫外(UV)交联得到交联型凝胶电解质薄膜。通过红外光谱、差示扫描量热、X-射线衍射、力学拉伸测试仪、扫描电镜、电化学交流阻抗谱、线性扫描伏安法等不同测试方法对不同交联组分比例下制得的凝胶聚合物电解质进行表征。结果表明:聚合物母体材料中MABP质量含量为30%时,综合性能较好的电解质在30℃时电导率可达1.16×10~(-4) S/cm;采用循环伏安法测得该电解质的电化学稳定窗口为+4.6 V(vs Li/Li~+),可以满足锂离子电池的应用要求;以所制备的凝胶聚合物电解质组装的锂离子电池在0.2 C的电流密度下,首次放电比容量达到245.2mAh/g。所制备的凝胶电解质与文献报道的同类电解质相比具有较宽的电化学稳定窗口和略低的离子电导率,而且具有较高的首次放电比容量,表明所设计的凝胶电解质具有在锂离子电池中应用的潜力。     

纳米Al_2O_3复合聚醚凝胶电解质性能

通过添加不同质量分数Al_2O_3纳米粒子制备硅甲氧基封端的聚环氧丙烷为基体的复合凝胶聚合物电解质(纳米Al_2O_3/LiBOB/PC/BSPPO)。采用拉伸测试、差热和热重分析、交流阻抗、线性伏安扫描及极化电流-时间曲线等方法对其进行了力学性能和热性能等物理性能测试以及离子电导率、电化学窗口和离子迁移数等电化学性能测试。研究结果表明:当Al_2O_3纳米粒子质量分数为15%时,该凝胶聚合物电解质室温电导率最佳,达到1.1×10-3 S·cm-1,同时表现出较高的拉伸强度,良好的热稳定性,电化学窗口为4.8 V,离子迁移数为0.61。应用于磷酸铁锂半电池中表现出良好的循环稳定性和倍率性能,说明该复合凝胶聚合物电解质具有潜在的应用和研究价值。     

碳基凝胶聚合物电解质双电层电容器的研究

为了克服液体电解液电容器的漏液和安全问题,以活性炭作电极材料,丙烯腈作聚合物单体,分别以碳酸丙烯酯 碳酸乙烯酯、碳酸二甲酯 碳酸乙烯酯和碳酸甲乙酯 碳酸乙烯酯的混合液作增塑剂,高氯酸锂为支持电解质盐,采用内聚合法制备了PAN基凝胶聚合物电解质双电层电容器(GPE-EDLCs).采用交流阻抗法测量了凝胶聚合物电解质(GPE)的离子电导率.采用交流阻抗、循环伏安、恒流充放电等测试方法研究了GPE-EDLCs的性能,并与有机电解液双电层电容器(LOE-EDLCs)进行了比较.结果表明,PAN基GPE的电导率在室温下为6.51～8.94 mS·cm-1,PAN基GPE-EDLCs的工作电压为2.5 V,电容器的比容量为43.9～47.4F/g(i=0.5 mA/cm2),能量密度为128.8～148.1 J/g,与LOE-EDLCs性质相近.     

复合凝胶聚合物电解质的制备及电化学性能

以偏氟乙烯和六氟丙烯共聚物为基体,通过与聚甲基丙烯酸甲酯共混,加入导电盐LiPFs、增塑剂聚乙烯吡咯烷酮,制备了高电导率的复合凝胶聚合物电解质（CGPE）。用红外光谱测试了聚合物电解质膜的结构,用交流阻抗法测试了CGPE的导电性能,用线性扫描伏安法研究了它的电化学稳定性。测试了以CGPE为电解质制备的锂离子电池的充放电性能。结果表明,当聚甲基丙烯酸甲酯（PMMA）质量分数为20％时,CGPE电导率大于10^-3s／cm,在4．65V电化学窗口以下稳定。以磷酸亚铁锂为正极时,在0．1C和0．2C倍率下放电时,聚合物电解质电池的首次放电容量分别为138mAh／g和98．3mAh／g。     

聚合物锂离子电池用凝胶电解质的研究进展

综述聚氧化乙烯(PEO)、聚偏氟乙烯(PVDF)、聚甲基丙烯酸甲酯(PMMA)和聚丙烯腈(PAN)等聚合物材料用作锂离子电池凝胶电解质的特性.PAN体系凝胶电解质的离子电导率一般在10-3S/cm数量级,其锂离子迁移数比PEO体系大,可达到0.5;与PAN基凝胶电解质相比,以PMMA为基的凝胶电解质与锂电极的界面稳定性和循环性能更好,但是机械强度较差;PVDF大分子链上含有很强的推电子基(-CF2),且介电常数较高(ε=8.4),有利于促进锂盐更充分的溶解,增加载流子浓度.提出添加无机纳米粒子的凝胶电解质是目前的研究热点,是凝胶电解质的发展趋势.     

PMMA系聚合物在锂离子电池凝胶电解质领域中的研究进展

综述了聚甲基丙烯酸甲酯(PMMA)作为锂离子电池凝胶电解质的特性及应用情况.PMMA基凝胶电解质与锂金属电极的界面稳定性好,室温离子电导率高达10-3 S/cm数量级,循环充放电性能好;但较差的机械强度限制了其应用,因此常采取共混、涂覆以及共聚等不同方式与其他高聚物、无机纳米粒子、聚烯烃膜乃至非织造膜等结合,制备出复合凝胶电解质使用.指出未来研究趋势是采用静电纺丝技术制备出分层复合聚合物电解质.     

聚乙二醇二丙烯酸酯基透明凝胶电解质的制备及其性能研究

将三氟甲烷磺酸锂(LiCF3SO3)、碳酸丙烯酯(PC)、聚乙二醇二丙烯酸酯(PEGDA)以及2,2-二甲氧基-2-苯基苯乙酮(DMPAP)混匀后,采用紫外光固化法制备高分子透明凝胶电解质.其中,LiCF3SO3、PC、PEGDA和DMPAP的加入量是影响凝胶电解质电导率的四个主要因素,各因素分别设置5个水平,采用L25(54)正交设计进行试验,以凝胶电解质的电导率作为考察指标.通过极差分析,得出影响电导率的因素顺序为LiCF3SO3PCPEGDADMPAP,制备试验中LiCF3SO3、PC和PEGDA的最佳质量比为0.3∶3∶1.采用紫外-可见光谱仪、XRD、四探针电导率测定仪分别对凝胶电解质的光透过率、结晶程度和电导率进行了表征.结果表明,所制备的凝胶电解质具有较高的可见光透过率和电导率.通过在水中浸泡及外界自然环境下放置试验,测试表明所制得的凝胶电解质的稳定性较好.     

改性无机微粒掺杂的固体聚合物电解质

为了提高锂离子电池固体聚合物电解质的电导率,用硫酸对纳米SiO₂和TiO₂进行表面改性,并加入到PEO基体中.采用溶液铸膜法制备出无机微粒 LiClO₄PEO全固态聚合物电解质（SPE）.运用数字显微镜、交流阻抗和拉伸测试对电解质膜的性能进行了表征,研究了无机微粒中w（酸）对电解质电导率的影响.结果表明,SiO₂微粒中w（酸）对电导率影响不大;TiO₂微粒中的w（酸）与电导率成正比.当w（酸）=8%时,电解质的室温电导率可达1.83×10^-6 S/cm.改性后的TiO₂ 微粒,可进一步提高固体聚合物电解质的电导率.     

聚衣康酸/聚丙烯酸互穿网络水凝胶的研究

以聚衣康酸（PIAc）网络为基础，通过分步互穿聚合物网络（IPN）技术引入了聚丙烯酸（PAAc）网络，制得了一种新的由具有同种官能团的2种聚合物互穿而成的全IPN水凝胶。通过研究聚衣康酸水凝胶、聚丙烯酸水凝胶和IPN水凝胶在不同pH条件下的溶胀性能，发现3种水凝胶随着pH增加，溶胀率变大，均表现出pH敏感性。IPN水凝胶的溶胀规律与聚衣康酸、聚丙烯酸水凝胶的溶胀规律相比有明显的差别。     

纳米SiO2的改性及其复合电解质的性能分析

锂离子电池具有高电压、高容量和高比能量等特点,是重要的储能器件。针对传统的液态锂离子电池容易发生电解液泄漏、燃烧爆炸和短路等问题,聚合物锂离子电池虽可以较好地解决安全问题,但仍存在电导率、离子迁移分数和力学性能较低等因素。以叔丁醇钾与纳米SiO2表面的羟基进行反应,再将1,3-丙磺酸内酯进行接枝反应,对纳米SiO2表面进行接枝改性;以改性和未改性的纳米 SiO2与苯乙烯、甲基丙烯酸甲酯进行聚合反应,制备SiO2/P（ MMA-S）复合聚合电解质。FT-IR和TGA研究结果表明,纳米SiO2表面含有丙磺酸锂基团。采用扫描电镜研究改性前后的纳米SiO2颗粒的形态,发现改性后纳米SiO2粒度分布均匀、团聚减弱。SiO2/P（ MMA-S）复合聚合物电解质的研究结果表明,含有质量比为6℅的改性纳米SiO2的复合电解质膜的吸液率可达310℅,经历15 d失重率不超过18℅,抗拉强度可达40.0 MPa以上,断裂伸长率也超过40℅,交流阻抗法测定其室温电导率可达3.98×10-3 S/cm。     

Synthesis and properties of physically crosslinked poly (vinyl alcohol) hydrogels

The present study is an investigation of the properties of poly (vinyl alcohol), which would be a better contact lens material than conventional HEMA in some ways. A transparent PVA hydrogel was prepared from a PVA solution in a mixed solvent consisting of water and a water-miscible organic solvent, DMSO, by the freezing-thawing method. The water content, visible light transmittance, mechanical and swelling properties of the hydrogels were evaluated as a function of PVA concentration and number of freeze-thaw cycles. The results show that the properties of PVA hydrogels depend on the polymer concentration, the number of freeze-thaw cycles and the addition of the organic solvent.     

Enhancing the formation of starch-based hybrid hydrogel by incorporating carboxyl groups into starch chains

A novel starch-based hybrid hydrogel was formed by physical and mild steps. Firstly, aqueous solution of a mixture of starch maleic half-ester (SM) and poly(vinyl alcohol) (PVA) was subjected to freezing-thawing cycles to generate a physical functional SM/PVA hydrogel. Subsequently, the SM/PVA/HA hybrid hydrogel was obtained through the alternate soaking process. The structure and morphology of the hydrogels were examined with Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). It was found that the existence of carboxylic groups on SM chains not only enabled SM/PVA hydrogel to be pH-sensitive, but also enhanced the formation of hydroxyapatite in the hydrogel via chelating calcium ions onto the matrix.     

Electrochemical behaviors of novel composite polymer electrolytes for lithium batteries

A novel composite polymer electrolyte was prepared by blending an appropriate amount of LiC104 and 10% (mass fraction) fumed SiO2 with the block copolymer of poly (ethylene oxide) (PEO) synthesized by poly (ethylene glycol) (PEG) 400 and CH2CI2.The ionic conductivity, electrochemical stability, interfacial characteristic and thermal behavior of the composite polymer electrolyte were studied by the measurements of AC impedance spectroscopy, linear sweep voltammetry and differential scanning calorimetry (DSC), respectively. The glass transition temperature acts as a function of salt concentration, which increases with the LiC104 content.Lewis acid-base model interaction mechanism was introduced to interpret the interactive relation between the filled fumed SiO2 and the lithium salt in the composite polymer electrolyte. Over the salt concentration range and the measured temperature, the maximum ionic conductivity of the composite polymer electrolyte (10^4.41 S/cm) appeared at EO/Li=25 (mole ratio) and 30~C, and the beginning oxidative degradation potential versus Li beyond 5 V.     

可修复水凝胶光子晶体的制备

采用冷冻-解冻法制备物理交联聚乙烯醇(PVA)水凝胶,在常温下可通过简单贴合实现断口自修复。考察了不同冷冻时间和解冻时间对自修复后水凝胶断裂拉伸应力的影响,结果表明,冷冻时间为24 h,解冻时间为1 h,所得水凝胶在自修复后具有最佳机械性能。进一步研究发现,以PVA水凝胶为基体包封180 nm聚苯乙烯(PS)微球制备的凝胶光子晶体(PC)可通过断面涂覆PVA溶液实现常温自修复,且PVA PCs可以制备成任意形状。衍射光谱表征证明了PVA PCs能够对外部压力刺激产生响应。     

电子束辐射制备pH敏感性聚乙烯醇水凝胶

应用电子束辐射交联技术制备了聚乙烯醇接枝丙烯酸(PVA-g-AAc)水凝胶。研究了pH值、AAc单体用量和辐照剂量等因素对PVA-g-AAc水凝胶溶胀率的影响。实验结果表明,在1 697cm-1处,PVA-g-AAc水凝胶的红外光谱图上出现强烈的羰基的C O特征峰,表明AAc成功接枝到PVA分子上;PVA-g-AAc水凝胶的溶胀率随PVA/AAc/H2O中AAc的质量分数和浸泡时间增加而增大;在pH=9.2时,PVA-g-AAc水凝胶具有显著的pH敏感性;辐射剂量为15kGy时,由PVA/AAc/H2O(1/1/20,质量比)混合溶液制备的PVA-g-AAc水凝胶具有较高的溶胀率;辐射剂量为5kGy时,由PVA/AAc/H2O(1/5/20,质量比)混合溶液制备的PVA-g-AAc水凝胶具有较高的溶胀率。     

Preparation and Swelling Behavior of Physically Crosslinked Hydrogels Composed of Poly（vinyl alcohol） and Chitosan

The physically crosslinked poly（vinyl alcohol）/chitosan （CS） composite hydrogels were prepared by cyclic freezing/thawing techniques, and the microstructure and swelling behavior of the hydrogels in the simulated gastric （pH 1.0） and intestinal （pH 7.4） media were investigated. The experimental results of infrared spectra （IR）, scanning electron microscope （SEM） and differential scanning calorimetry （DSC） demonstrated that poly（vinyl alcohol） and chitosan had good miscibility in the composite hydrogels, and the addition of chitosan perturbed the formation of poly（vinyl alcohol） crystallites. The swelling kinetics results indicated that the composite hydrogels had good pH sensitive properties to the acidic environments, and with the increase of chitosan content in the blend, the maximum swelling degreed and the swelling rate both increased, but it led to more dissolution at pH 1.0. And the composite hydrogels also exhibited good reversible swelling behavior with pH value of the swelling medium altering between 1.0 and 7.4. In addition, the higher freezing/thawing cycle times resulted in the lower swelling rate. Therefore, the swelling behavior of the composite hydrogels could be adjusted by changing the chitosan contents and the freezing/thawing cycle times.     

聚乙烯吡咯烷酮改善聚乙烯醇水溶液的电纺性研究

聚乙烯醇（PVA）水溶液中的高价金属离子与PVA大分子链上的羟基相互作用，形成了分子内和分子间的交联结构，降低了可纺性。添加具有羰基和亚氨基双官能团聚乙烯吡咯烷酮（PVP）后，由于PVP优先络合高价金属离子，这样，使PVA大分子链从交联结构中游离出来，提高了PVA的可纺性。当PVP过量时，PVP又与PVA形成交联作用，反而降低了PVA的可纺性。     

聚乙烯醇-壳聚糖水凝胶制备与溶胀行为的研究

研究了聚乙烯醇与壳聚糖质量比、溶剂醋酸溶液体积、交联剂戊二醛浓度等对聚乙烯醇-壳聚糖水凝胶溶胀性能的影响,正交实验的结果表明当聚乙烯醇与壳聚糖质量比为2、溶剂醋酸体积为100 mL、交联剂戊二醛的浓度为0.213 mol/L时凝胶溶胀度最大.凝胶溶胀度随着聚乙烯醇与壳聚糖质量比、交联剂戊二醛浓度的增大而减小,随着溶剂醋酸溶液体积增加而增大.     

Preparation and electrochemical properties of polymer Li-ion battery reinforced by non-woven fabric

A polymer electrolyte based on poly(vinylidene) fluoride-hexafluoropropylene was prepared by evaporating the solvent of dimethyl formamide, and non-woven fabric was used to reinforce the mechanical strength of polymer electrolyte and maintain a good interfacial property between the polymer electrolyte and electrodes. Polymer lithium batteries were assembled by using LiCoO2 as cathode material and lithium foil as anode material. Scanning electron microscopy, alternating current impedance, linear sweep voltammetry and charge-discharge tests were used to study the properties of polymer membrane and polymer Li-ion batteries. The results show that the technics of preparing polymer electrolyte by directly evaporating solvent is simple. The polymer membrane has rich micro-porous structure on both sides and exhibits 280% uptake of electrolyte solution. The electrochemical stability window of this polymer electrolyte is about 5.5 V, and its ionic conductivity at room temperature reaches 0.151 S/m. The polymer lithium battery displays an initial discharge capacity of 138 mA·h/g and discharge plateau of about 3.9 V at 0.2 current rate. After 30 cycles, its loss of discharge capacity is only 2%. When the battery discharges at 0.5 current rate, the voltage plateau is still 3.7 V. The discharge capacities of 0.5 and 1.0 current rates are 96% and 93% of that of 0.1 current rate, respectively.