环亚硫酸甘油酯衍生物作为电解液添加剂对锂离子电池电化学性能的影响

在亚硫酸酯基团的基础上引入苯环,设计并合成了3种环亚硫酸甘油酯衍生物[双(1,2-环亚硫酸甘油酯)对苯二甲酸酯、三(1,2-环亚硫酸甘油酯)均苯三甲酸酯和四(1,2-环亚硫酸甘油酯)均苯四甲酸酯],通过倍率充放电、恒流充放电、交流阻抗和扫描电子显微镜等测试研究了这些添加剂对锂离子电池性能的影响.结果表明,与空白电解液相比,加入三(1,2-环亚硫酸甘油酯)均苯三甲酸酯的电解液球化石墨电极表面可形成一层致密而稳定的固体电解质界面(SEI)膜,从而优化电极-电解液的界面性能,改善电池的倍率性能和循环性能,且在循环80周后电池阻抗增加较小;而双(1,2-环亚硫酸甘油酯)对苯二甲酸酯和四(1,2-环亚硫酸甘油酯)均苯四甲酸酯的加入不会明显改善电池的循环性能.研究结果表明苯环上亚硫酸甘油酯基团的数目对其性能影响较大.     

甲基丙烯酸类聚合物修饰的聚乙烯隔膜在锂离子电池中的应用

将环状碳酸酯基团引入到聚甲基丙烯酸甲酯(PMMA)侧链上, 制备了聚(2,3-环碳酸甘油酯)甲基丙烯酸酯(PDOMMA), 并用其修饰锂离子电池聚乙烯隔膜. 通过热重分析、 差示扫描量热分析及接触角和吸液率测试等研究了PDOMMA的热稳定性及其修饰的聚乙烯隔膜对电解液的浸润性和吸液率的影响, 并通过恒流充放电、 交流阻抗、 倍率性能测试及扫描电子显微镜观测等研究了修饰隔膜对锂离子电池性能的影响. 结果表明, 与未修饰隔膜相比, 修饰隔膜对电解液浸润性更优异(20 s内便完全浸润), 吸液率更高(440%), 电池循环性能更好(放电比容量提高了12.3%).     

晶态Li_4Ti_5O_(12)负极材料的制备及其与电解液的兼容性研究

本文以醋酸锂和钛酸丁酯为原料,以冰醋酸为抑制剂,采用溶胶-凝胶法制备了晶态Li4Ti5O12负极材料。与自制的3种电解液和实验室常用的电解液分别组装成锂/钛酸锂半电池。采用恒流充放电测试、循环伏安法(CV)及交流阻抗法(EIS)对其电化学性能进行研究。研究结果发现:在以环状碳酸酯类(EC、PC)和线性碳酸酯类(MEC)为溶剂、以六氟磷酸锂(LiPF6)为电解质的电解液中添加双乙二酸硼酸锂(LiBOB),有利于提高半电池的性能,首次放电比电容达到了198mA.h.g-1,且放电比电容经多次充放电后衰减得较小。而在电解液中加入碳酸亚乙烯酯(VC),半电池的性能有所下降。Li4Ti5O12对电解液表现出较明显的兼容性。     

添加剂氟代碳酸乙烯酯对锂离子电池性能的影响

在1 mol·L-1 LiPF6/碳酸乙烯酯(EC)+碳酸二甲酯(DMC)+碳酸甲乙酯(EMC)(EC、DMC、EMC体积比为1:1:1)电解液中加入体积比为2%的添加剂氟代碳酸乙烯酯(FEC), 用循环伏安法(CV)、扫描电镜(SEM)、能量散射光谱(EDS)、电化学阻抗谱(EIS)等方法, 研究了FEC 对锂离子电池性能及石墨化中间相碳微球(MCMB)电极/电解液界面性质的影响. 结果表明, 体积比2%FEC的添加可以抑制部分电解液溶剂的分解, 在MCMB电极表面形成一层性能优良的固体电解液相界面(SEI)膜, 降低了电池的阻抗, 明显提高了电池的比容量和循环稳定性.     

白藜芦醇对长期贮存锂离子电池电解液性能的影响

锂离子电池电解液从制造完成到使用,一般都会经历灌装、运输和贮存的过程,了解长期贮存过程对锂离子电池电解液性能的影响,对锂离子电池的生产具有一定的理论指导意义。本文运用电化学阻抗谱(EIS)测试并结合循环伏安法(CV)测试、充放电测试、扫描电子显微镜(SEM)等研究了1 mol·L^-1 LiPF₆-EC:EMC基础电解液中添加不同浓度白藜芦醇(RES)时,在长期贮存过程中对石墨电极性能的影响及机制。研究结果表明,新鲜的基础电解液在经历6个月的贮存后,石墨电极在其中无论是可逆循环容量还是循环稳定性(容量保持率)均出现大幅度的下降。这主要是由于在经历6个月贮存后的基础电解液中,石墨电极表面形成的 SEI 膜较厚,进而导致锂离子嵌入过程的不稳定造成的。在基础电解液中添加不同浓度的白藜芦醇均能有效抑制电解液长期贮存造成的石墨电极在其中电化学性能的下降,当基础电解液中含有200 ppm白藜芦醇经历6个月贮存后,石墨电极无论是可逆容量还是循环性能稳定性甚至优异于在新鲜的电解液中。     

丙酸乙酯对LiFePO4锂离子电池低温性能的影响

以丙酸乙酯(EP)作为碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)和碳酸二甲酯(DMC)的共溶剂,研究其对LiFePO4锂离子电池低温电化学性能的影响.利用循环伏安曲线、交流阻抗图谱和恒电流充放电曲线等方法测试电池电化学性能.结果表明,添加一定量EP,可提高碳酸酯电解液的离子电导率,改善电解液与正极LiFePO4材料和负极石墨材料的相容性,从而提高LiFePO4锂离子电池的低温性能.使用1 mol·L-1LiPF6/(EC:EMC:DMC:EP=1:1:1:3,by mass)电解液的石墨/LiFePO4锂离子电池在10oC(1C)、-10oC(0.2C)、-20oC(0.2C)、-30oC(0.2C)和-40oC(0.2C)下的相对放电容量(以25oC时的放电容量为基准)分别为82.9%、75.6%、59.0%、46.4%和37.6%.     

温度对石墨电极性能的影响

运用电化学阻抗谱(EIS)并结合循环伏安法(CV)研究了石墨电极25和60 ℃时在1 mol·L-1 LiPF6-EC(碳酸乙烯酯):DEC(碳酸二乙酯):DMC(碳酸二甲酯)电解液中, 以及60 ℃时在1 mol·L-1 LiPF6-EC:DEC:DMC+5%VC(碳酸亚乙烯酯)电解液中的首次阴极极化过程. 发现高温下(60 ℃)石墨电极在1 mol·L-1 LiPF6-EC:DEC:DMC电解液中可逆循环容量衰减的主要原因在于其表面无法形成稳定的固体电解质相界面(SEI)膜. 实验结果显示, VC添加剂能够增进高温下石墨电极表面SEI膜的稳定性, 进而改进石墨电极的循环性能.     

腈基功能化有机硅基电解液在4.4V钴酸锂/石墨锂离子电池中的性能研究

研究了3-丙基腈-甲氧基乙氧基-二甲基硅烷(SN1)作为电解液共溶剂对高电压钴酸锂/石墨全电池电化学性能的影响.在商业烷基碳酸酯电解液里掺入30%SN1(体积分数),钴酸锂/石墨全电池在4.4 V截止电压下仍表现出良好的循环稳定性和倍率性能:以0.5 C充放电,首次放电比容量为154 mA h/g,循环150周后,容量保持率为92.9%;当放电倍率增加到1和1.5 C时,放电容量分别为143和133 mA h/g.电化学阻抗谱、扫描电镜和傅里叶红外光谱的结果表明,耐高电压腈基功能化有机硅化合物的引入有效抑制了共溶剂电解液在正极材料表面的分解,压制了循环过程中电极极化的增长,为电极/电解液界面的Li+扩散和电荷转移提供了有利的动力学条件.     

对苯二甲酸镁作为钠离子电池的有机负极材料

报道了对苯二甲酸镁作为钠离子电池负极材料的研究.以对苯二甲酸和氢氧化镁为原料,采用酸碱中和反应制备了含结晶水的对苯二甲酸镁(MgC8H4O4·2H2O),该材料对钠离子电池表现出了较好的电化学活性、优异的倍率性能以及良好的循环稳定性.在0.5C(1C=300 mA·g-1)倍率下循环50周以后,可逆容量由114mAh·g-1降至95 mAh·g-1,容量保持率高达83%;在2C的倍率下有高达90 mAh·g-1的可逆比容量.另外,在氮气气氛中,400℃进行后续热处理得到了不含结晶水的对苯二甲酸镁(MgC8H4O4),探讨了结晶水对其电化学性能的影响.结果表明,MgC8H4O4·2H2O的比容量、倍率性能以及循环稳定性都明显优于不含结晶水的对苯二甲酸镁.     

不可燃氟代碳酸酯基钠离子电池电解液（英文）

锂离子电池由于其较高的能量密度而在我们的日常生活中被广泛使用,比如手机、笔记本电脑和电动汽车。然而,地球上有限的锂资源可能会阻碍其进一步的发展。近来,由于丰富的资源、合适的电化学平台和低廉的价格,钠离子电池正得到大家越来越多的关注,有希望成为下一代主流储能体系。然而,跟锂离子电池类似,钠离子电池的电解液主要是由易燃的有机碳酸酯或醚类溶剂、钠盐和一些添加剂组成,这就带来了安全隐患。此外,钠金属具有比锂更高的化学活性,导致钠离子电池可能具有比锂离子电池更大的危险性。为了解决这个安全性问题,我们提出一种不可燃的氟代碳酸酯基电解液。电解液成分是由0.9 mol·L~(-1) Na PF6溶解在氟代碳酸乙烯酯(FEC)和二-2,2-三氟乙基碳酸酯(TFEC)(3:7,体积比)混合溶剂中组成。测试结果表明,该电解液体系不仅具有优异的阻燃能力,而且与钠离子电池的正负极都具有很好地相容性。在此电解液中,普鲁士蓝正极时表现出色的电化学性能,循环50圈后,仍有84 m Ah·g~(-1)的容量。此外,商业化硬碳材料在该电解液中也表现出了较好的电化学性能。这项工作可能为开发下一代安全型钠离子电池提供新途径。     

二氟草酸硼酸钠作为电解液添加剂对石墨负极性能的影响

锂离子电池日益广泛的应用对其性能提出越来越高的要求,而在电解液中加入适当的添加剂能够显著提升电极材料的电化学性能. 本文首次在1 mol·L^-1 LiPF₆/EC + DMC + EMC（体积比1:1:1）的电解液中添加一定量的二氟草酸硼酸钠(NaDFOB),并通过循环伏安（CV）、电化学阻抗图谱（EIS）和扫描电子显微镜（SEM）等分析考察了其对石墨负极材料性能的具体影响. 结果显示,添加NaDFOB的电解液显著提高了石墨材料在常温下的可逆充放电容量和循环性能,同时明显改善了石墨材料的高温循环性能. 其机理在于NaDFOB的阴阳离子同时参与了石墨表面固体电解质界面膜（SEI）的形成,形成高稳定性的电解液/电极界面.     

An efficient high-yield synthesis of D-ribo-phytosphingosine

[Structure: see text] [4R-[4alpha(S),5alpha]]-2,2-Dimethyl-4-(2-oxo-5-vinyl[1,3]dioxolan-4-yl)oxazolidine-3-carboxylic acid tert-butyl ester 5a, obtained in excellent yield and diastereoselectivity by the alpha-hydroxyallylation of the Garner aldehyde (4), is exploited in a novel high-yield synthesis of D-ribo-phytosphingosine (8), using microwave-enhanced cross metathesis as the key step in the chain elongation.     

Stepwise unidirectional synthesis of oligo phenylene vinylenes with a series of monomers. Use in plastic solar cells

Four new monomers for directional stepwise synthesis of oligophenylenevinylenes (OPVs) (4-{2-[4-(5,5-dimethyl[1,3]dioxan-2-yl)-2,5-dipropoxyphenyl]vinyl}benzyl)phosphonic acid diethyl ester, (5-{2-[4-(5,5-dimethyl[1,3]dioxan-2-yl)-2,5-dipropylphenyl]vinyl}thiophene-2-ylmethyl)phosphonic acid diethyl ester, (5-{2-[4-(5,5-dimethyl[1,3]dioxan-2-yl)-2,5-dipropoxyphenyl]vinyl}thiophene-2-ylmethyl)phosphonic acid diethyl ester, and (7-{2-[4-(5,5-dimethyl[1,3]dioxan-2-yl)-2,5-dipropylphenyl]vinyl}benzo[1,2,5]thiadiazol-4-ylmethyl)phosphonic acid diethyl ester have been prepared. Trimeric OPVs were then synthesized and tested as active materials in photovoltaic cells. Conversion efficiencies in the range of 0.5-1% were obtained in blends with the soluble C(60) derivative PCBM. A terpyridine end-functionalized trimer and a heterotrimer with a mixed composition of monomers were also prepared.     

New poly(ester amide ether amide)s from a novel flexible diamine and different diacid chlorides using TMSCl for in situ silylation

A novel flexible diamine with built-in ester, amide and ether groups named terephthalic acid bis(4-{2-[2-(2-amino ethoxy)ethoxy]ethyl carbamoyl}phenyl) ester (TABE), was synthesized via two steps. Nucleophilic reaction of 4-hydroxybenzoic acid with terephthaloyl chloride in the presence of NaOH yielded terephthaloyl bis (4-oxybenzoic) acid (TOBA). The diamine (TABE) was prepared via two direct and indirect methods. In the indirect method TOBA was converted to related diacid chloride and reacted with 1,8-diamino-3,6-dioxaoctane (DADO). Direct method was achieved through the reaction of TOBA with DADO via Yamazaki method. TOBA and TABE were fully characterized and TABE was used to prepare new poly(ester amide ether amide)s through polycondensation with different diacid chlorides in the presence of trimethylchlorosilane (TMSCl). The polymers were characterized using conventional methods and their physical properties including inherent viscosity, thermal behavior, thermal stability, crystallinity, and solubility were studied. The polymers showed good thermal stability and improved solubility.     

Rhenium tricarbonyl core complexes of thymidine and uridine derivatives

Thymidine and uridine were modified at the C2' and C5' ribose positions to form amine analogues of the nucleosides (1 and 4). Direct amination with NaBH(OAc)3 in DCE with the appropriate aldehydes yielded 1-{5-[(bis(pyridin-2-ylmethyl)amino)methyl]-4-hydroxytetrahydrofuran-2-yl}-5-methyl-1H-pyrimidine-2,4-dione (L1), 1-{5-[(bis(quinolin-2-ylmethyl)amino)methyl]-4-hydroxytetrahydrofuran-2-yl}-5-methyl-1H-pyrimidine-2,4-dione (L2), and 1-[3-(bis(pyridin-2-ylmethyl)amino)-4-hydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl]-1H-pyrimidine-2,4-dione (L5), while standard coupling procedures of 1 and 4 with 5-(bis(pyridin-2-ylmethyl)amino)pentanoic acid (2) and 5-(bis(quinolin-2-ylmethyl)amino)pentanoic acid (3) in the presence of HOBT-EDCI in DMF provided a second novel series of bifunctional chelators: 5-(bis(pyridin-2-ylmethyl)amino)pentanoic acid [(3-hydroxy-5-(5-methyl-4-oxo-3,4-dihydro-2H-pyrimidin-1-yl)tetrahydrofuran-2-yl)methyl] amide (L3), 5-(bis(quinolin-2-ylmethyl)amino)pentanoic acid [(3-hydroxy-5-(5-methyl-4-oxo-3,4-dihydro-2H-pyrimidin-1-yl)tetrahydrofuran-2-yl)methyl] amide (L4), 5-(bis(pyridin-2-ylmethyl)amino)pentanoic acid [2-(2,4-dioxo-3,4-dihydro-2H-pyrimidin-1-yl)-4-hydroxy-5-(hydroxymethyl)tetrahydrofuran-3-yl] amide (L6), and 5-(bis(quinolin-2-ylmethyl)amino)pentanoic acid [2-(2,4-dioxo-3,4-dihydro-2H-pyrimidin-1-yl)-4-hydroxy-5-(hydroxymethyl)tetrahydrofuran-3-yl] amide (L7). The rhenium tricarbonyl complexes of L1-L4, L6, and L7, [Re(CO)3(LX)]Br (X=1-4, 6, 7: compounds 5-10, respectively), have been prepared by reacting the appropriate ligand with [NEt4][Re(CO)3Br3] in methanol. The ligands and their rhenium complexes were obtained in good yields and characterized by common spectroscopic techniques including 1D and 2D NMR, HRMS, IR, cyclic voltammetry, UV, and luminescence spectroscopy and X-ray crystallography. The crystal structure of complex 6.0.5NaPF6 displays a facial geometry of the carbonyl ligands. The nitrogen donors of the tridentate ligand complete the distorted octahedral spheres of the complex. Crystal data: monoclinic, C2, a = 24.618(3) A, b = 11.4787(11) A, c = 15.5902(15) A, beta = 112.422(4) degrees , Z = 4, D(calc) = 1.562 g/cm3.     

C,O-dialkylation of Meldrum's acid: synthesis and reactivity of 1,3,7,7-tetramethyl-4H,10H-6,8,9-trioxa-2-thiabenz[f]azulen-5-one

Reaction of Meldrum's acid with 3,4-bis(chloromethyl)-2,5-dimethylthiophene (1) or 3,4-bis(bromomethyl)-2,5-dimethylthiophene (2) produces the kinetically favored C,O-dialkylation product, 1,3,7,7-tetramethyl-4H,10H-6,8,9-trioxa-2-thiabenz[f]azulen-5-one (4). Recrystallization of 4 from refluxing methanol results in the methanolysis product 5-(4-methoxymethyl-2,5-dimethylthiophen-3-ylmethyl)-2,2-dimethyl[1,3]dioxane-4,6-dione (5). Attempts to isomerize 4 to the thermodynamically favored C,C-dialkylation product, 1,3-dimethyl-5,6-dihydro-4H-cyclopenta[c]thiophene(2-spiro-5)2,2-dimethyl-4,6-dione (8), result in the formation of 1,3-dimethyl-7,8-dihydro-4H-thieno[3,4-c]oxepin-6-one (6). The transformation occurs via a retro-Diels-Alder elimination of acetone followed by hydrolysis and decarboxylation of the resulting ketene. The ketene is trapped by tert-butyl alcohol, furnishing 1,3-dimethyl-6-oxo-7,8-dihydro-4H,6H-thieno[3,4-c]oxepine-7-carboxylic acid tert-butyl ester (7). All compounds are characterized spectroscopically as well as by X-ray crystallography of products 4-7.     

石墨负极在Et4NBF4+LiPF6/EC+PC+DMC电解液中的电化学行为

在PC+EC+DMC复合溶剂体系中, 研究了Et4NBF4(四氟硼酸四乙基铵)与LiPF6组成的复合盐电解质对石墨负极材料界面性质的影响. 用循环伏安和恒电流充放电测试方法研究了电解液与石墨负极的相容性, 通过傅里叶变换红外光谱(FTIR)对固体电解质中间相膜(SEI)的成分变化进行了研究. 结果表明, 电解液中的Et4NBF4参与了SEI膜的形成; 当Et4NBF4浓度为0.2 和0.5 mol·L-1时, 电池首次充放电不可逆容量损失明显减少, 循环效率分别上升到76.0%和81.6%. Et4NBF4/LiPF6复合盐电解质改善了PC基电解质与石墨负极的相容性.     

Condensed isoquinolines 32. Synthesis of 4H-thieno-[3′,2′:5,6]-and-[2′,3′: 5,6]pyrimido-[1,2-b]isoquinolines and 6,12-dihydro-5H-isoquino-[2,3-a]quinazoline-5,12-dione derivatives

Treatment of 2-(4-oxo-3,4-dihydrothieno[2,3-d]-and-[3,2-d]pyrimidin-2-ylmethyl)benzoic acids and 2-(4-oxo-3,4-dihydro-2-quinazolinylmethyl)benzoic acid with acetic anhydride gave thieno[3′,2′:5,6]-and-[2′,3′:5,6]pyrimido[1,2-b]isoquinoline-4,11-diones and isoquino[2,3-a]quinazoline-5,12-dione respectively. NMR spectroscopy showed that an intramolecular acylation of the above acids occurs at the atom N-1 of the pyrimidinone part of the bicycle. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1053–1061, July, 2008.     

Synthesis and screening of some novel substituted indoles contained 1,3,4-oxadiazole and 1,2,4-triazole moiety

A series of novel 3-[5-(1H-indol-3-yl-methyl)-2-oxo-[1,3,4]oxadiazol-3-yl]propionitrile(5),3-[4- amino-3-(1H-indol-3-yl-methyl)-5-oxo-4,5-dihydro-[1,2.4]triazol-1-yljpropionitrile(6),3-[5-(1H- indol-3-yl-methyl)-2-thioxo-[1,3,4]oxadiazol-3-yl]propionitrile(7) and 3-[4-amino-3-(1H-indol-3-yl-methyl) -5-thioxo-4,5-dihydro-[1,2,4]triazol-l -yljpropionitrile(8) were synthesized in good yields from the intermediate(1H-indol-3-yl)-acetic acid N’-(2-cyanoethyl)hydrazide(4).The chemical structures of the newly synthesized compounds were elucidated by their IR,~1H NMR and MS.Further,all the compounds were screened for their antimicrobial activity against Gram-positive,Gram-negative bacteria and also tested their ability toward anti-inflammatory activity.     

Synthesis and conversions of 3-(4-amino-5-methyl-4H-1,2,4-triazol-3-ylmethylene)-2-oxo-1,2,3,4-tetrahydroquinoxaline

The reaction of the hydrazone 3a with hydrazine hydrate in DBU/ethanol conveniently gave 3-(4-amino-5-methyl-4H-1,2,4-triazol-3-ylmethylene)-2-oxo-1,2,3,4-tetrahydroquinoxaline 6 . The reactions of 6 with an equimolar and 2-fold molar amount of nitrous acid afforded 3-(α-hydroxyimino-4-amino-5-methyl-4H-1,2,4-triazol-3-ylmethyl)-2-oxo-1,2-dihydroquinoxaline 9 and 3-(α-hydroxyimino-5-methyl-2H-1,2,4-triazol-3-ylmethyl)-2-oxo-1,2-dihydroquinoxaline 10 , respectively, which were converted into the 3-heteroarylisoxazolo[4,5-b]quin-oxalines 13a,b and 11 , respectively. Compound 9 was also cyclized into the 8-quinoxalinyl-1,2,4-triazolo-[3,4-f][1,2,4]triazines 14a,b .