原位聚合法制备凝胶型离子液体/PMMA聚合物电解质

采用原位聚合法制备了含有N-甲基、丙基哌啶双三氟甲磺酰亚胺离子液体的凝胶型聚合物电解质．利用SEM和XPS测试了电解质膜与LiFePO₄电极的界面状态,充放电循环后,在电解质膜与LiFePO₄之间有一层薄膜,这层薄膜中含有N和S元素．结果表明,随着充放电的不断进行,凝胶型电解质中未聚合的甲基丙烯酸甲酯与电极表面的锂离子之间发生电子转移,形成SEI膜,至少要三个循环后才能形成稳定的SEI膜．随着SEI膜的增厚,放电容量增加,阻碍了电子转移,使系统更加的稳定．在不同     

高性能的钛掺杂O3相O3-Na1-xCr1-xTixO2(x=0, 0.03, 0.05)用于钠离子电池正极材料的研究

本文通过凝胶热聚合路线合成了层状的O3相正极材料Na_1-xCr_1-xTi_xO₂(x=0, 0.03, 0.05),采用X射线衍射、扫描电子显微镜来分析其晶体结构和微观形貌. 研究发现,适量的钛掺杂有助于形成更均匀的颗粒并且会改变样品的颜色. 作为钠离子电池正极材料,Na//Na_0.97Cr_0.97Ti_0.03O₂具有非常高的库伦效率(首次高于96%),并且在2.0-3.6 V的电化学窗口下,用0.2 C的倍率循环100次,只有4%的容量衰减;在32 C倍率下有110 mAh/g的比容量.     

OCS分子在128 nm附近的光解动力学研究：S(3PJ=2,1,0)、S(1D2)以及S(1S0)产物通道

本文利用时间切片离子成像技术对OCS分子进行了真空紫外波段的光解动力学研究. 在四个光解光波长(从129.32到126.08 nm)下测量了硫原子解离产物S(³P_J=2,1,0)、S(¹D₂)、S(¹S₀)的速度影像，并从中清晰地发现了四个主要的解离产物通道：S(³P_J=2,1,0)+CO(X¹Σ⁺)，S(³P_J=2,1,0)+CO(A³π)，S(¹D₂)+CO(X¹Σ⁺)和S(¹S₀)+CO(X¹Σ⁺). 在实验影像中，产物CO分子的部分振动态结构能够得到分辨. 实验还获取解离产物总平动能谱，产物分支比和角分布. 对实验结果进行分析显示除绝热解离通道S(³P_J=2,1,0)+CO(A³π)之外，在其他三个产物通道中非绝热效应都起到非常重要的作用.     

2-三氟甲基吡啶的转动光谱及分子结构研究

本文测定了2-三氟甲基吡啶在2∽20 GHz频率范围内的高分辨转动光谱. 测定了转动常数、¹⁴N核四极耦合常数及离心畸变常数等一系列光谱参数. 同时还在自然丰度下测定了5个¹³C和1个¹⁴N单取代同位素异数体的光谱数据. 实验结果结合从头算准确地推导出2-三氟甲基吡啶的骨架结构. 实验测得同位素异数体的平面转动惯量P_cc数值均为44.46 u?²，表明此分子具有C_s对称性. 此外，本文计算了吡啶、2-氟吡啶、2-甲基吡啶和2-三氟甲基吡啶的分子表面静电势，以此分析了三氟甲基的取代对电子分布的影响.     

交叉分子束实验研究F+D2(v=1, j=0)反应

本文使用交叉分子束方法研究了氟原子和振动激发态氘分子D₂(v=1, j=0)的反应. 使用受激拉曼抽运的方法制备了振动激发的D₂分子. 实验中未观测到来自于旋轨耦合激发态氟原子F^*(²P_1/2)与振动激发态D₂分子的贡献. 观测到来自于旋轨耦合基态氟原子F(²P_3/2)和振动激发态D₂的反应信号,相应的产物DF分子布居于v''=2,3,4,5振动态上. 与振动基态反应F+D₂(v=1,j=0)相比,振动激发态反应F+D₂(v=1,j=0)生成的DF产物转动分布更“热”. 获得了振动激发反应的四个碰撞能在0.32至2.62 kcal/mol范围内的微分反应截面. 在最低的碰撞能0.32 kcal/mol下,所有振动态的DF产物都以后向散射为主. 随着碰撞能的增加,DF产物的角分布逐渐从后向转移到侧向. 测量了DF(v''=5)产物的前向微分散射截面随碰撞能变化的曲线. 前向散射的DF(v''=5)信号出现于1.0 kcal/mol. 在2.62 kcal/mol碰撞能下DF(v''=5)主要为前向散射.     

化学计量的氧化钠团簇阳离子结构的离子迁移质谱法研究

本文通过离子迁移质谱法研究了氧化钠团簇阳离子(Na_nO_m⁺,n≤11)的稳定结构. 质谱结果表明化学计量组成Na(Na₂O)_(n-1)/2⁺ (n=3、5、7、9和11)系列是稳定的,并且NaO(Na₂O)_(n-1)/2⁺ (n=5、7、9和11)系列作为二级稳定系列. 为了获得这些团簇离子的结构,通过离子迁移率测量实验测定离子和氦缓冲气体之间的碰撞截面. 同时计算了这些组合物优化结构的理论碰撞截面. 结果表明,Na(Na₂O)_(n-1)/2⁺和NaO(Na₂O)_(n-1)/2⁺的结构除了n=9之外,其它具有相似结构框架. Na(Na₂O)_(n-1)/2⁺所有的化合键位于钠和氧之间. 另一方面,NaO(Na₂O)_(n-1)/2⁺中除了Na-O键之外,还存在一个O-O氧键,表明NaO(Na₂O)_(n-1)/2⁺具有过氧化物离子(O₂^2-)作为Na(Na₂O)_(n-1)/2⁺的氧化物离子(O^2-) 的替代物. Na(Na₂O)_(n-1)/2⁺和NaO(Na₂O)_(n-1)/2⁺两种稳定系列都是闭壳组合物. 这些闭壳特征对氧化钠簇阳离子的稳定性具有强烈影响.     

OCS分子在里德堡F态的真空紫外光解动力学：S(3PJ=2,1,0)产物通道

本文利用可调谐真空紫外光源和时间切片离子速度成像技术研究了OCS分子的真空紫外光解动力学. 在对应OCS里德堡F态的五个光解波长下(133.26 nm∽139.96 nm)实验采集了S(³P_J=2,1,0)产物的离子影像,从中发现了两个解离通道：S(³P_J=2,1,0)+CO(X¹Σ⁺)和S(³P_J=2,1,0)+CO(A³π),其中前者为主要通道. 离子影像中CO产物的振动结构可部分分辨. 从离子影像中提取出了S(³P_J=2,1,0)+CO(X¹Σ⁺)通道的产物总平动能分布、各向异性参数和CO振动态分支比等信息. 发现了对应OCS在F态的几个低振动态下光解的产物各向异性参数取负值,而对应F态的几个高振动态下光解产物的各向异性参数为正值. 另外,同一光解波长下三种S产物S(³P₂)、S(³P₁)和S(³P₀)的各向异性参数也不相同. 经分析,这些现象可能来源于激发区域的其它不同对称性的电子态的贡献,从而导致解离过程中同时存在平行解离和垂直解离. 本工作有利于进一步理解OCS真空紫外光解中的非绝热耦合作用.     

Ti+(CO2)2Ar和Ti+(CO2)n(n=3-7)络合物离子的红外光解离光谱 (cited: 1)

利用脉冲激光溅射-超声分子束载带方法制备了气相Ti⁺(CO₂)₂Ar和Ti⁺(CO₂)_n(n=3-7)络合物离子．采用红外光解离光谱研究了这些选定的质量离子的振动光谱． 对于每一种络合物离子, 在CO伸缩振动频率范围都观察到了振动峰,表明这些离子具有插入的OTi⁺CO(CO₂)_n-1结构． 对于n≦5的OTi⁺CO(CO₂)_n-1离子,其CO振动和CO₂的反对称伸缩振动频率都比自由的CO和CO₂的频率要高,表明CO和CO₂配体与中心金属离子之间主要是静电相互作用．实验结果还表明TiO⁺可以直接络合五个配体(1个CO和4个CO₂分子)．对于n=2络合物体系,除了插入的OTi⁺CO(CO₂)结构以外,还观察到了具有弯曲结构的OCO-Ti⁺-OCO异构体的存在     

钙钛矿型中温固体氧化物燃料电池阴极Ba0.5Sr0.5Al0.1Fe0.9O3-δ

研究一种新型不含钴的钙钛矿型中温固体氧化物燃料电池阴极Ba_0.5Sr_0.5Al_0.1Fe_0.9O_3-δ (BSAF)材料的晶体结构、电导率以及在对称电池中的电极极化性能. 研究发现,BSAF阴极在空气中低于450 oC表现出典型的具有正温度系数的半导体行为,最高电导率达到14 S/cm;在450-750 oC,却表现出负温度系数,且电导率在750 oC下降到6 S/cm. 电化学研究表明,在基于混合离子导体的对称电池中,BSAF阴极在650-700 oC表现出良好的电极极化性能.以3%H₂O/H₂为燃料和空气为氧化剂,单电池在700 oC的开路电压和最大功率输出分别达到420 mW/cm².     

OCS经由F 31Π里德堡态生成CO(X1Σ+)+S(1D2)产物的波长相关性光解离

本文利用时间切片离子速度成像技术在134∽140 nm波段研究了OCS分子经由F 3¹Π里德堡态的真空紫外光解离动力学. 在选取的5个分别对应OCS(F 3¹Π, v₁=0∽4)的伸缩振动激发的光解波长，实验测得了来自CO(X¹Σ⁺)+S(¹D₂)产物通道的SS(¹D₂))实验影像，并获得了总平动能谱和CO(X¹Σ⁺, v)共生产物的振动布居及角分布. 结果分析表明OCS分子解离生成CO(X¹Σ⁺)+S(¹D₂)产物的过程经历了上态F 3¹Π 与C_?v和C_s构型的下电子态间非绝热耦合过程. 实验结果显示了很强的波长相关性：OCS (F 3¹Π, v₁)的较低转动激发态(v₁=0∽2)和较高转动激发态(v₁=3, 4)的CO(X¹Σ⁺)产物的振动布居和角分布具有显著差异，表明该解离过程中具有不同的解离机理. 本结果提供了振动耦合可能对真空紫外光解离动力学产生关键作用的相关证据.     

A novel and shortcut method to prepare ionic liquid gel polymer electrolyte membranes for lithium-ion battery

The ionic liquid polymer electrolyte (IL-PE) membrane is prepared by ultraviolet (UV) cross-linking technology with polyurethane acrylate (PUA), methyl methacrylate (MMA), ionic liquid (Py₁₃TFSI), lithium salt (LiTFSI), ethylene glycol dimethacrylate (EGDMA), and benzoyl peroxide (BPO). N-methyl-N-propyl pyrrolidinium bis(trifluoromethanesulfonyl)imide (Py₁₃TFSI) ionic liquid is synthesized by mixing N-methyl-N-propyl pyrrolidinium bromide (Py₁₃Br) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The addition of Py₁₃TFSI to polymer electrolyte membranes leads to network structures by the chain cross-linking. The resultant electrolyte membranes display the room temperature ionic conductivity of 1.37 × 10^?3 S cm^?1 and the lithium ions transference number of 0.22. The electrochemical stability window of IL-PE is about 4.8 V (vs. Li⁺/Li), indicating sufficient electrochemical stability. The interfacial resistances between the IL-PE and the electrodes have the less change after 10 cycles than before 10 cycles. IL-PE has better compatibility with the LiFePO₄ electrode and the Li electrode after 10 cycles. The first discharge performance of Li/IL-PE/LiFePO₄ half-cell shows a capacity of 151.9 mAh g^?1 and coulombic efficiency of 87.9%. The discharge capacity is 131.9 mAh g^?1 with 95.5% coulombic efficiency after 80 cycles. Therefore, the battery using the IL-PE exhibits a good cycle and rate performance.     

Electrochemical characterization of ionic liquid based gel polymer electrolyte for lithium battery application

High molecular weight polymer poly(vinylidenefluoride-co-hexafluoropropylene) (PVdF-HFP), ionic liquid 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIMFSI), and salt lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)-based free-standing and conducting ionic liquid-based gel polymer electrolytes (ILGPE) have been prepared by solution cast method. Thermal, electrical, and electrochemical properties of 80 wt% IL containing gel polymer electrolyte (GPE) are investigated by thermogravimetric (TGA), impedance spectroscopy, linear sweep voltammetry (LSV), and cyclic voltammetry (CV). The 80 wt% IL containing GPE shows good thermal stability (~?200 °C), ionic conductivity (6.42?×?10^?4 S cm^?1), lithium ion conductivity (1.40?×?10^?4 S cm^?1 at 30 °C), and wide electrochemical stability window (~?4.10 V versus Li/Li⁺ at 30 °C). Furthermore, the surface of LiFePO₄ cathode material was modified by graphene oxide, with smooth and uniform coating layer, as confirmed by scanning electron microscopy (SEM), and with element content, as confirmed by energy dispersive X-ray (EDX) spectrum. The graphene oxide-coated LiFePO₄ cathode shows improved electrochemical performance with a good charge-discharge capacity and cyclic stability up to 50 cycles at 1C rate, as compared with the without coated LiFePO₄. At 30 °C, the discharge capacity reaches a maximum value of 104.50 and 95.0 mAh g^?1 for graphene oxide-coated LiFePO₄ and without coated LiFePO₄ at 1C rate respectively. These results indicated improved electrochemical performance of pristine LiFePO₄ cathode after coating with graphene oxide.     

Lithium solvation in a PMMA membrane plasticized by a lithium‐conducting ionic liquid based on 1‐butyl‐3‐methylimidazolium bis(trifluoromethanesulfonyl)imide

The Raman and Infrared (IR) spectra of poly(methyl methacrylate) (PMMA) membranes plasticized by ionic liquids of the (1 − x)[1‐butyl‐3‐methylimidazolium bis(trifluoromethanesulfonyl)imide (BMITFSI)],xLiTFSI type, where BMI⁺ is the 1‐butyl‐3‐methylimidazolium cation and TFSI⁻ the bis(trifluoromethanesulfonyl)imide anion, are analyzed for a lithium bis(trifluoromethane sulfone)imide (LiTFSI) mole fraction x = 0.23 and PMMA contents from 0 to 50 wt%. The lithium is found to have an average coordination of about three CO groups and less than one TFSI⁻ anion. It plays the role of a cross‐linker between the ester groups of PMMA and the nonvolatile ionic liquid. Addition of PMMA to the (1 − x)(BMITFSI),xLiTFSI ionic liquid lowers the conductivity but might improve the lithium transference number by transforming the [Li(TFSI)₂]⁻ anionic clusters present in the pure ionic liquid into a mixed coordination by ester groups and TFSI⁻ anions. Copyright © 2008 John Wiley & Sons, Ltd.     

A piperidinium-based ester-functionalized ionic liquid as electrolytes in Li/LiFePO<Subscript>4</Subscript> batteries

A new functionalized ionic liquid (IL) based on cyclic quaternary ammonium cations with ester group and bis(trifluoromethanesulfonyl)imide ([TFSI]^?) anion, namely, N-methyl-N-methoxycarbonylpiperidinium bis(trifluoromethanesulfonyl)imide ([MMOCPip][TFSI]), was synthesized and characterized. Physical and electrochemical properties, including Li-ion transference number, ionic conductivity, and electrochemical stability, were investigated. The electrochemical window of [MMOCPip][TFSI] was 6 V, which was wide enough to be used as a common electrolyte material. The Li-ion transference number of this IL electrolyte containing 0.1 M LiTFSI was 0.56. The half-cell tests indicated that the [MMOCPip][TFSI] obviously improved the cyclability of a Li/LiFePO₄ cell. For the Li/LiFePO₄ half-cells, after 20 cycles at room temperature at 0.1 C, the discharge capacity was 109.7 mAh g^?1 with 98.7% capacity retention in the [MMOCPip][TFSI]/0.1 M LiTFSI electrolyte. The good electrochemical performance demonstrated that the [MMOCPip][TFSI] could be used as electrolyte for lithium-ion batteries.     

Solid polymer electrolytes based on poly(lithium carboxylate) salts

The ionic conductivity, lithium ion transference number, electrochemical stability, and thermal property of solid polymer electrolytes composed of poly(ethylene oxide) (PEO) and poly(lithium carboxylate)s, (poly(lithium acrylate) (Poly(Li-A)) or poly(lithium fumarate) (Poly(Li-F)), with and without BF₃·OEt₂ were investigated. The ionic conductivities of all solid polymer electrolytes were enhanced by one to two orders of magnitude with addition of BF₃·OEt₂ because the dissociation of lithium ion and carboxylate anion was promoted by the complexation with BF₃. The lithium ion transference number in the solid polymer electrolytes based on poly(lithium carboxylate)s showed relatively high values of 0.41–0.70, due to the suppression of the transport of counter anion by the use of a polymeric anion. The solid polymer electrolytes with addition of BF₃·OEt₂ showed good electrochemical stability.     

Vibrational,electrical, and ion transport properties of PVA-LiClO<Subscript>4</Subscript>-sulfolane electrolyte with high cationic conductivity

Novel solid polymer electrolytes, poly(vinylalcohol)-lithium perchlorate (PVA-LiClO₄) and PVA-LiClO₄-sulfolane are prepared by solvent casting method. The experimental results show that sulfolane addition enhances the ionic conductivity of PVA-LiClO₄ complex by three orders. The maximum ionic conductivity of 1.14 ± 0.20 × 10^?2 S cm^?1 is achieved for 10 mol% sulfolane-added electrolyte at ambient temperature. Polymer-salt-plasticizer interactions are analyzed through attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. Lithium ion transference number is found by AC impedance spectroscopy combined with DC potentiostatic measurements. The results confirm that sulfolane improves the Li⁺ transference number of PVA-LiClO₄ complex to 0.77 from 0.40. The electrochemical stability window of electrolytes is determined by cyclic voltammetry (CV). The broad electrochemical stability window of 5.45 V vs. lithium is obtained for maximum conducting electrolyte. All-solid-state cell is fabricated using maximum conducting electrolyte, and electrochemical impedance study is carried out. It reveals that electrolyte interfacial resistance with Li electrode is very low. The use of PVA-LiClO₄-sulfolane as a viable electrolyte material for high-voltage lithium ion batteries is ensured.     

Lithium ion transport and ion-polymer interaction in PEO based polymer electrolyte plasticized with ionic liquid

The polyethylene oxide (PEO) based lithium ion conducting polymer electrolytes complexed with lithium trifluoromethanesulfonate (LiCF₃SO₃ or LiTf) plasticized with an ionic liquid 1-ethyl 3-methyl imidazolium trifluoromethanesulfonate (EMITf) have been reported. Morphological, spectroscopic, thermal and electrochemical investigations demonstrate promising characteristics of the polymer films, suitable as electrolyte in various energy storage/conversion devices. Significant structural changes have been observed in the polymer electrolyte due to the ionic liquid addition, investigated by X-ray diffraction (XRD) and optical microscopy. The ion-polymer interaction, particularly the interaction of imidazolium cation with PEO chains, has been evidenced by IR and Raman spectroscopic studies. The optimized composition of the polymer electrolyte i.e. PEO_25.LiTf + 40 wt.% EMITf offer room temperature ionic conductivity of ~ 3 × 10^− 4 S cm^− 1 with wide electrochemical stability window and excellent thermal stability. The ‘σ versus 1/T’ curves show apparent Arrhenius behavior below and above melting temperature. The ionic conductivity has been observed due to Li⁺ ions, as confirmed from ⁷Li-NMR studies, though the component ions of ionic liquid and anions also contribute significantly to the overall conductivity.     

Influence of nano-sized fumed silica on physicochemical and electrochemical properties of cellulose derivatives-ionic liquid biopolymer electrolytes

Nanocomposite biopolymer electrolyte was prepared by solution-casting technique. Carboxymethyl cellulose from kenaf bast fibre, ammonium acetate, (1-butyl)trimethyl ammonium bis(trifluoromethylsulfonyl)imide ionic liquid and silica nanofiller was used to prepare the biopolymer electrolyte samples. The films were characterized by Fourier transform infrared spectroscopy, electrochemical impedance spectroscopy, scanning electron microscopy, transference number measurement and linear sweep voltammetry. The interactions of doping salt, ionic liquid and inorganic nanofiller with the host biopolymer were confirmed by FTIR study. The highest conductivity achieved was 8.63 × 10^?3 S cm^?1 by the incorporation of 1 wt% of SiO₂ at ambient temperature. The electrochemical stability of the highest conducting sample was stable up to 3.4 V, and the ion transference number in the film was 0.99.     

Triethylbutylammonium bis(trifluoromethanesulphonyl)imide ionic liquid as an effective electrolyte additive for Li-ion batteries

Ionic liquids are promising additives for Li-ion batteries owing to its desirable physicochemical properties. Triethylbutylammonium bis(trifluoromethanesulphonyl)imide ([N₂₂₂₄][Tf₂N]) ionic liquid was synthesized and their physical and electrochemical properties were investigated. Among several quaternary ammonium ionic liquids, [N₂₂₂₄][Tf₂N] exhibited higher conductivity (1.31 mS?cm^?1), better thermal and electrochemical stabilities, and wide electrochemical window, i.e., more than 5.9 V. Standard solution was prepared by dissolving lithium bis(trifluoromethanesulphonyl)imide (LiTf₂N) in ethylene carbonates/dimethyl carbonate (1:1, by weight). The conductivity for the electrolyte containing [N₂₂₂₄][Tf₂N] and the mixed electrolyte without additives at 25 °C are 10.24 and 8.79 mS?cm^?1, respectively. LiFePO₄ half-cell containing 0.6 mol?L^?1 LiTf₂N-based organic electrolyte with [N₂₂₂₄][Tf₂N] showed relatively high initial discharge capacity and coulombic efficiency at first cycle. It is found that the mix [N₂₂₂₄][Tf₂N] electrolyte exhibits relatively high-rate capacity. The capacity retention of half-cell containing [N₂₂₂₄][Tf₂N] is 2 % more than without additive at 0.2 C. However, the rate capacity retention of the half-cell with mix [N₂₂₂₄][Tf₂N] electrolyte is above 10 % more than without additive at 0.5 C. The results showed that [N₂₂₂₄][Tf₂N] was an effective electrolyte additive in LiFePO₄ half-cell.     

New polymer electrolyte based on (PVA–PAN) blend for Li-ion battery applications

A polymer blend electrolyte based on polyvinyl alcohol (PVA) and polyacrylonitrile (PAN) was prepared by a simple solvent casting technique in different compositions. The ionic conductivity of polymer blend electrolytes was investigated by varying the PAN content in the PVA matrix. The ionic conductivity of polymer blend electrolyte increased with the increase of PAN content. The effect of lithium salt concentrations was also studied for the polymer blend electrolyte of high ionic conductivity system. A maximum ionic conductivity of 3.76×10⁻³ S/cm was obtained in 3 M LiClO₄ electrolyte solution. The effect of ionic conductivity of polymer blend electrolyte was measured by varying the temperature ranging from 298 to 353 K. Linear sweep voltammetry and DC polarization studies were carried out to find out the stability and lithium transference number of the polymer blend electrolyte. Finally, a prototype cell was assembled with graphite as anode, LiMn₂O₄ as cathode, and polymer blend electrolyte as the electrolyte as well as separator, which showed good compatibility and electrochemical stability up to 4.7 V.