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1.
以氢氧化锂、电解超细二氧化锰为原料,在不同条件下用溶胶-泥浆法制备了尖晶石型LiMn2O4,优化了反应条件并以此作正极材料进行了电化学测试。结果表明,首次充电比容量达125mAh.g^-1~145mAh.gA^-1,放电比容量达115mAh.gA^-1~125Ah.g^-1。可逆充放电效率在90%以上,循环28次后其充电比容量仍然保持在110mAh.g^-1~115mAh.g^-1,放电比容量达1  相似文献   

2.
纳米晶钛镧酸盐的水热合成和表征   总被引:13,自引:6,他引:7  
报道了在TiO2-La2O3-M2O-H2O水热体系中,新型钛镧酸盐M0.5La0.5TiO3(M=La,Ag0.66Na0.33,Li0.6Na0.4)的水热合成,用XRD、SEM、TEM、ICP、DTA-TG、IR和ac阻抗分析技术进行了结构表征。讨论了水热合成反应体系pH、反应混合物的组成比以及晶化温度等因素对合成的影响。XRD分析表明,Na0.5La0.5TiO3和Ag0.33Na0.17  相似文献   

3.
CaO-SiO2-Al2O3-MgO-TiOx-FeOy体系氧化动力学   总被引:3,自引:1,他引:2  
用电动势和化学分析方法研究了富钛还原熔渣-CaO-SiO2-Al2O3-MgO-TiO2-FeOy体系的氧化动力学,得出了氧在熔渣中的扩散速率常数分别为0.66*10^-5m.s^-1和1.98*10^-5m.s^-1,研究表明:固体电解质构成的氧浓差电池法得出的结果不仅可靠,且方法快速,简便。  相似文献   

4.
用循环伏安和红外光谱法对α-Fe_2O_3在室温LiOH溶液中的锂化行为进行研究.采用X射线衍射(XRD)、电感偶合等离子体光源的原子发射光谱(ICP)对α-Fe_2O_3电极在第一、二次循环中不同时段进行了跟踪分析测量.实验结果揭示: α-Fe_2O_3能进行少量锂化;大量的α-Fe_2O_3在第一次放电和充电后反应生成Fe_3O_4;之后,Fe_3O_4的锂化行为不可避免地为Fe的析出、氧化反应所限制,但在用KOH作电解质溶液的对比实验时发现:α-Fe_2O_3在LiOH溶液中的充放电行为与它在KOH溶液中是不同的,主要表现为,1)在LiOH溶液中,锂化和Fe析出、氧化反应协调的结果是其充放电曲线平台高度比在同碱度 KOH溶液中降低了 100 mV左右, 2)与 K~(+)对比, Li~(+)的插入反应促进了α-Fe_2O_3到Fe_3O_4的转化.  相似文献   

5.
酒石酸法合成的LiCoO2的结构及其二次锂电池行为研究   总被引:16,自引:0,他引:16  
章福平 《电化学》1995,1(3):342-347
采用X射线衍射,光电子能谱,库仓滴定,循环伏安等方法研究酒石酸法合成的LiCoO2的结构及其二次锂电池行为,结果表明LiCoO2具有六方晶系R^-3m空间群结构,相应晶胞参数a=0.2810nm,c=1.4088nm;其中Co^3+为低自旋;且其表面存在Li2O.同时,其二次锂电池电容量可达120mA.h.g^-1,半容量工作电压达3.8V,当正极中Li^+的含量(X)为0.451≤x≤0.934  相似文献   

6.
二次Li/LiNi0.3Co0.7O2电池反应研究   总被引:1,自引:0,他引:1  
章福平 《电化学》1996,2(3):305-309
利用循环伏安,库仑滴定,X射线衍射,恒电流阶跃等方法研究了Li/LiNi0.2Co0.7O2电池反应。结果表明该电池在4.30-3.00V间放电容量可达120-140mA.h.g^-1,充,放电机理为Li^+在LiNi0.3Co0.7O2中进行两步脱嵌与嵌入反应。  相似文献   

7.
申双龙 《分析化学》1998,26(11):1339-1341
报道了苄氧基甲基-12-冠-3-的合成,并以此化合物作载体研制成锂离子选择电极。用苄氧基甲基-12冠-3-为载体的电极对锂离子响应拇性范围为1.0×10^-1-8.3×10^-5mol/L.检测限为4.2×10^-5mol/L,斜率为57.4mV/pLi。电极具有好的稳定性和重现性。  相似文献   

8.
研究了3,5-Br2-PADAP在酸性介质中质子化,与IO^-3和SCN^-形成三元离子缔合物的最佳条件,其表现摩尔吸光系数为1.4*10^5L.mol^-1.cm^-1,缔合物组成比为3,5-Br2-PADAP:IO^3:SCN^-=1:1:1。  相似文献   

9.
本较详细研究了在H2SO4介质中,Ti(Ⅳ)-F^--o-NPF-CPC体系水相光度法测定痕量钛的新方法。四元体系的最大吸收峰在565nm处,表观摩尔吸光系数为2.1×10^5L.mol^-^1.cm^-^1,Sandell灵敏度为2.28×10^-^4μgTi/cm^2。钛含量在0-4μg/25mL范围内遵宁比尔定律。方法用于土壤,粮食,牧草,蔬菜和中草药中钛的测定,结果满意。  相似文献   

10.
液相法合成锂离子电池正极材料Li1+xMn2O4   总被引:11,自引:0,他引:11  
采用柠檬酸络合和溶液浸渍两种方法制备Li1+xMn2O4正极材料,用XRD和BET测试了材料晶体结构和比表面积,考察焙烤温度、Li/Mn比、起始原料对产物结构和电化学性能的影响,结果表明,焙烧温度与Li/Mn比是影响材料电化学性能的关键因素,确定了制备Li1+xMn2O4材料最佳条件为0≤x≤0.05,焙烧温度750℃,所得电池材料首次充放电容量达到120mAh/g,循环50次后,春充放电容量为1  相似文献   

11.
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.  相似文献   

12.
KMnO4-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.  相似文献   

13.
The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.  相似文献   

14.
An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.  相似文献   

15.
Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.  相似文献   

16.
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.  相似文献   

17.
18.
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.  相似文献   

19.
The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion.  相似文献   

20.
Quercetin, the polyphenolic compound, which has the highest daily intake, is well known for its protective effects against aging diseases and has received a lot of attention for this reason. Both quercetin 3-O-β-d-glucuronide and quercetin 3′-O-β-d-glucuronide are human metabolites, which, together with their regioisomers, are required for biological as well as physical chemistry studies. We present here a novel synthetic route based on the sequential and selective protections of the hydroxyl functions of quercetin allowing selective glycosylation, followed by TEMPO-mediated oxidation to the glucuronide. This methodology enabled us to synthesize the five O-β-d-glucosides and four O-β-d-glucuronides of quercetin, including the major human metabolite, quercetin 3-O-β-d-glucuronide.  相似文献   

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