LiNi0.8Co0.2-XMXO2的合成和电化学性能研究

锂离子电池手机、笔记本电脑、电动汽车技术、医疗仪器电源以及宇宙空间等领域。目前商品化锂离子电池正极活性材料主要是LiCoO2、LiNiO2、LiMn2O4,及其掺杂化合物。LiNiO2具有比容量高,功率大、价格适中等优点,但也存在合成困难,热稳定性差等问题,其实用化进程一直比较缓慢。     

添加磷、硼、硅和铝的锂离子电池材料LiNiO2研究

研究了添加元素磷，硼硅和铝对锂离子蓄电池材料LiNiO2的影响。添加磷，硼、硅和铝的目的是提高LiNiO2的放电平台和充放电稳定性，增加循环寿命并且提高充放电能量，在n(LiOH):n(Ni(OH)2)为1.1:1.0的材料中分别加入P2O5;H3BO3,SiO2,Al2O3，保持4种元素与锂的摩尔比值分别为0.01,0.02,0.03,0.04和0.05，分析测定了样品的充放电曲线和循环伏安曲线，并采用XRD对样品的放电过程和合成产品进行了结构分析，结果证明，当n(P)/n(Ni)=0.02,n(B)/n(Ni)=0.03,n(Si)/n(Ni)\0.02,n(Al)/n(Ni)=0.02时，LiNiO2的放电电压提高，添加元素使LiNiO2在充放电过程中的晶型转变过程发生改变，使六方晶系向单斜晶系转变的趋势变小，这将改善LiNiO2的循环性能，但没有影响锂离子的嵌入和脱嵌机理，XRD分析表明，添加磷和铝使LiNiO2的层状结构更完善，同时增加了活性，但添加硼和硅以后，LiNiO2的XRD图上的衍射峰（003）强度度减弱，衍射峰（018）和（019）峰也有改变，这证明B和Si影响了LiNiO2性能。     

新型电池材料LiNiyCozTi1-x-yO2的结构与性能研究

研究了新型锂离子电池材料LiNiyCozTi1-x-yO2的结构与性能,比较了LiNiyCozTi1-x-yO2与LiNiO2在充放电特性、物性、粒度分布等方面的异同,研究了LiNiyCozTi1-x-yO2的结构和电化学性能.结果表明,部分Ni被Co和Ti取代后,有效地改善了LiNiO2的性能.     

锂离子电池正极材料LiNi_(0.85)Co_(0.10)(TiMg)_(0.025)O_2合成及表征

以LiOH·H2O、Ni2O3、Co2O3、TiO2和Mg(OH)2为原料,应用固相反应法合成Co Ti Mg共掺杂的LiNiO2化合物LiNi0. 85Co0. 10 (TiMg)0. 025O2;TG DTA、XRD、SEM和电化学测试表明,该材料首次放电容量达182. 7mAh/g(3. 0~4. 3V, 18mA/g), 10次循环之后,容量还有 175. 5mAh/g,容量保持率为 96. 2%;与未掺杂的LiNiO2相比,该材料显示出良好的循环性能,是一种很有应用前景的锂电池正极材料.     

低热固相反应法制备纳米LiCoO2的研究(Ⅰ)

LiCoO2是目前商品锂离子电池的正极材料.虽然其价格昂贵,但与LiNiO2或LiMn2O4等相比,LiCoO2较易合成且生产工艺较成熟,因此其性能改进仍受到普遍关注.目前LiCoO2的合成方法主要是高温固相法[1～4],一般在700～900℃范围内烧结得到HT-LiCoO2;此外还可用低热法得到LT-LiCoO2[5～7];或通过CoOOH/LiOH·H2O/H2O混合物经H+/Li+离子交换得到LiCoO2[8].     

新型电池材料LiNi_yCo_zTi_(1-y-z)O_2的结构与性能研究

研究了新型锂离子电池材料LiNiyCozTi1 - y-zO2 的结构与性能 ,比较了LiNiyCozTi1 - y-zO2 与LiNiO2 在充放电特性、物性、粒度分布等方面的异同 ,研究了LiNiyCozTi1 -y-zO2 的结构和电化学性能 .结果表明 ,部分Ni被Co和Ti取代后 ,有效地改善了LiNiO2 的性能 .     

高容量正极材料0.08LiCo0.75Al0.25O2-0.92LiNiO2的合成与电化学性能研究

在恒定pH值下将层状钴铝双羟基复合金属氧化物(CoAl-LDH)均匀包覆在球状Ni(OH)2表面,与LiOH.H2O混合均匀后,经高温煅烧制得钴铝酸锂包覆镍酸锂0.08LiCo0.75Al0.25O2-0.92LiNiO2正极材料.电化学测试表明,0.08LiCo0.75Al0.25O2-0.92LiNiO2正极比容量高,具有良好的倍率性能和循环寿命,其0.1C放电比容量为211 mAh·g-1,0.5C放电比容量为195.6 mAh·g-1,3C放电比容量为161 mAh·g-1,0.5C 30周期循环后容量保持率为93.2%,明显优于LiNiO2和钴酸锂包覆镍酸锂0.08LiCoO2-0.92LiNiO2正极.     

Studies on Synthesis and Electrochemical Performance of Li_(1+δ) Ni_(1-x)Co_xO_(2-y)F_y Cathode Materials for Lithium-ion Batteries?

It is a technological problem of LiNiO2 cathode material for lithium-ion secondary batteries because of the difficult preparation and hard purification, instable performance, remarkable capacity fading at initial discharge, worse thermal stability and safety of Ni-series cathode materials, and it is also the key factor of hindering LiNiO2 cathode material from practical applications. Recently, by doping some metal cations such as Co, Mn, Mg, Al, Cr and so on[1-5] into LiNiO2, the preparat…     

低共熔混合锂盐相图的绘制及应用

采用热分析法对不同组成的混合锂盐二元体系进行研究, 绘制了混合锂盐体系的步冷曲线和T-x相图, 结果表明体系均为具有最低共熔点的二元体系. LiOH-LiNO3、LiOH-LiCl、LiOH-Li2CO3及LiNO3-LiCl体系的最低共熔点分别为175.7、294.5、418.2及221.6 ℃. 利用低共熔混合物LiNO3-LiOH为锂盐与不同前驱体反应, 制备出了层状结构良好的锂离子电池正极材料LiNiO2、LiNi0.8Co0.2O2及LiNi1/3Co1/3Mn1/3O2. X射线衍射分析表明, 合成的材料具有规整的层状NaFeO2结构, 且XRD衍射峰强度之比I(003)/I(104)>2.0, 电性能测试表明, 在2.7-4.3 V(vs Li/Li+)的电压范围内进行0.1C倍率充放电, LiNiO2、LiNi0.8Co0.2O2、LiNi1/3Co1/3Mn1/3O2首次充电比容量分别达168.0、225.4、194.0 mAh·g-1, 放电比容量分别为138.4、165.8、157.7 mAh·g-1.     

锂离子二次电池正极材料镍酸锂的量子化学研究

利用周期性体系的Hartree-Fock方法计算了以LiC6／LiNiO2锂离子二次电池的平均电压，结果与实验值相差 15％。计算表明，NiO2中嵌入一个Li原子变成LiNiO2后，负电荷主要从Li转移到O上，转移到Ni上的负电荷仅约20％，讨论了其对Jahn-Tell效应的影响。以Li0.5NiO2作为嵌锂中间物的代表，研究了锂离子的可能迁移路径。通过对NiO2和LiNiO2的电子态密度的计算，研究了NiO2在嵌锂过程中的能带变化及其对电极的电化学性质的影响。     

高岭土原位无溶剂法合成小粒径ZSM-5分子筛

结合原位水热法和无溶剂法的优点,在不添加有机模板剂和溶剂的基础上,以高岭土为原料通过晶种诱导绿色高效地合成出ZSM-5分子筛。运用X射线衍射、N2吸附-脱附、扫描电镜、透射电镜和NH3程序升温脱附(TPD-NH3)等技术对ZSM-5分子筛进行表征。表征结果与原位水热法合成的ZSM-5分子筛相比,原位无溶剂法合成ZSM-5分子筛的结晶度较高、晶体粒径较小、酸强度略高、孔结构相似。     

Facile synthesis of cyclopentapeptide,cyclo[Arg(NO2)-Gly-Asp(OBn)-D-Phe-Lys(Fmoc)], and its application in synthesis of integrin-targeting anticancer conjugate

An efficient approach for integrin-targeting cRGDfK conjugate synthesis has been developed using a new protected cyclopentapeptide, cR(NO₂)GD(Bn)fK(Fmoc), as the key intermediate. cR(NO₂)GD(Bn)fK(Fmoc) was conveniently prepared in high yield. The Fmoc group of this cyclopentapeptide was selectively removed under mild conditions which makes it an ideal intermediate for cRGDfK conjugate synthesis as was well demonstrated in this paper by the synthesis of cRGDfK chlorambucil conjugate.     

Facile Synthesis of Metallosalphen-Based 2D Conductive Metal-Organic Frameworks for NO2 Sensing: Metal Coordination Induced Planarization

As an emerging class of promising porous materials, the development of two-dimensional conductive metal organic frameworks (2D c-MOFs) is hampered by the few categories and tedious synthesis of the specific ligands. Herein, we developed a nonplanar hexahydroxyl-functionalized Salphen ligand (6OH-Salphen) through a facile two-step synthesis, which was further applied to construct layered 2D c-MOFs through in situ one pot synthesis based on the synergistic metal binding effect of the N₂O₂ pocket of Salphen. Interestingly, the C_2v-symmetry of ligand endows Cu-Salphen-MOF with periodically heterogeneous pore structures. Benefitting from the higher metal density and shorter in-plane metal-metal distance, Cu-Salphen-MOF showcased excellent NO₂ sensing performance with good sensitivity, selectivity and reversibility. The current work opens up a new avenue to construct 2D c-MOF directly from nonplanar ligands, which greatly simplifies the synthesis and provides new possibilities for preparing different topological 2D c-MOF based functional materials.     

A Facile Synthesis of Pure O2PtF6

A new and facile synthesis of O₂PtF₆ is reported without the demanding synthesis of PtF₆ or the use of high pressure fluorination in the presence of oxygen. The O₂PtF₆ is obtained in form of single crystals by direct Klemm‐type fluorination of commercially available PtO₂ · xH₂O in a stream of diluted F₂ of atmospheric pressure at a temperature of 275 °C. Its identity and purity was evidenced by powder X‐ray diffraction, Raman and infrared spectroscopy. The synthesis allows the preparation of pure dioxygenyl hexafluoridoplatinate(V). The new synthesis of O₂PtF₆ is deemed more convenient than those that require the extremely reactive PtF₆.     

Synthesis of 3-Deoxy-3-C-Trifluoromethyl-d-Ribose From d-Xylose or d-Glucose

Abstract

The synthesis of 3-deoxy-1,2,O-isopropylidene-3-C-trifluoromethyl-α-D-ribofuranose is described. After a first approach from a commercial D-xylose derivative which was limited by an incomplete stereoselectivity, the synthesis of the title compound was performed from 1,2:5,6-di-O-isopropylidene-α-D-glucofuranose by a reaction sequence where key steps: trifluoromethylation with CF₃SiMe₃ and radical deoxygenation are highly stereoselective.     

Sol–gel combustion synthesis of chromium doped yttrium aluminum perovskites

A water-based sol–gel combustion synthesis was optimized in order to achieve pure yttrium aluminium perovskite (YAlO₃, YAP). The method involved three main steps: xerogel formation, combustion treatment and calcination of the combusted precursors. TG DTA, FTIR and XRPD, used to investigate the precursor phase evolution, confirmed the strong influence of gel synthesis conditions, combustion temperature and calcination rate on YAP purity. Both stoichiometry and kinetics control during all the preparation steps are crucial in order to avoid the formation of undesired Y₃Al₅O₁₂ (YAG) and Y₄Al₂O₉ (YAM) stable phases. This method allowed to synthesize, for the first time from an aqueous sol–gel process, single phase samples of YAP. A series of samples with composition: YAl_(1−x)Cr_(x)O₃ where x is 0, 0.035, 0.135, 0.250, 0.500, 0.750 was obtained. A consistent decrease of calcination temperature, with respect to conventional solid state synthesis, was achieved by sol–gel combustion, avoiding polyphase materials even without the use of mineralizers. This is an important result in several applications like the synthesis of ceramic pigments.     

纳米微孔NixZn(1-x)Fe2O4的水热合成研究

０引言尖晶石型铁酸盐是一类重要的磁性材料，它可用于防止电磁波辐射设备以及隐身材料中的吸波剂犤１，２犦，具有价格低廉、吸波性能优良的特点。同时尖晶石型铁酸盐也是一类重要的催化剂，９０年代初又发现了氧缺位的该类化合物具有将CO２还原为C的优良催化性能犤３犦。因此，有关铁酸盐的制备及性能研究一直是化学工作者和材料科学工作者感兴趣的领域。随着新的合成方法的不断涌现，对传统铁氧体材料进行结构改造以提高其性能是一个重要的研究发展方向，本文采用模板剂造孔技术，首次在NixZn（１－x）Fe２O４水热合成中选用模板剂，…     

固相合成甲胺基阿维菌素苯甲酸盐

To implement the solid phase synthesis of 4““-epi-methylamino-4““-deoxyavermecfin B1 benzoate, tert-butyldimethylsilylchloride was chosen for the first solution synthesis. Then a novel silyl chloride resin 1, achieved from hydroxymethyl polystyrene resin and dimethyldichlorosilane, was used successfully for the attachment of avermectin B1 2. Through oxidation, amination formation, cleavage, and benzoate formation, resin bounded avermectin B1 9 gave 4““-epi-methylamino-4““-deoxyavermectin B1 benzoate 3.     

QUANTITATIVE CORRELATION BETWEEN SPECTROPHOTOMETRIC PHYTOCHROME ASSAY AND PHYSIOLOGICAL RESPONSE

Abstract— Apparent synthesis* of the enzyme lipoxygenase in the cotyledons of the mustard seedling (Sinapis alba L.) is controlled by phytochrome (P_{fr ground state})? through a threshold (all-or-none) mechanism. This response was used to determine physiologically the photostationary states, Λ that is, the [P_fr]/[P_tot] ratios established by different wavelengths in the red and far-red range of the spectrum, including the standard red and far-red sources used in this laboratory (Mohr, 1966). Under the premises (for which justification has been given on previous occasions) that the [P_fr]/[P_tot] ratio for standard red light is 0.8, and that the decay of P_fr is a first-order process with a half-life of 45 min, the [P_fr]/[P_tot] ratios determined physiologically by means of the lipoxygenase response agree with the [P_fr]/[P_tot] ratios determined spectrophotometrically by Hartmann and Spruit (cf. Fig. 9 in Hanke et al., 1969) in hypocotyl hooks of mustard seedlings. In the hook the _fr, that is, the [P_fr]/[P_tot] ratio for standard far-red, is found to be 0.023. In the cotyledons, this ratio is several times higher (Schafer et al., 1972). The conclusion that apparent lipoxygenase synthesis in the cotyledons is controlled by phytochrome located in the hook has been substantiated by further spectrophotometric (Schäfer et al., 1973) and physiological experiments (H. Oelze-Karow and H. Mohr, in preparation). The minimum steepness of the threshold was determined. An increase of the P_fr level from 118 (relative units) to 130 leads to an instantaneous and total suppression of apparent lipoxygenase synthesis; a corresponding decrease from 130 (relative units) to 118 leads to an immediate resumption of apparent LOG synthesis at full speed. It is concluded that an explanation of the experimental facts requires a cooperative effect on the level of P_fr, a high degree of synchrony on the cellular and organismic level and rapid communication between the hypocotyl hook and the cotyledons. *The term ‘apparent synthesis’ is used operationally in the present paper to denote any increase of enzyme activity, although de novo synthesis of lipoxygenase has not so far been rigorously demonstrated. The usual inhibitor experiments (cf. Oelze-Karow et al., 1970) have led to the conclusion that intact RNA and protein synthesis is required for an increase of lipoxygenase activity.     

Power‐Law Kinetic Models for Synthesis of Ammonia Borane

In the past few years, there have been increasing numbers of studies for the production and dehydrogenation of ammonia borane (NH₃BH₃, AB), which has become a significant hydrogen storage material. However, kinetic model studies based on the synthesis of AB in the literature have not been encountered, though there are many kinetic modeling studies on dehydrogenation of AB (Akbayrak et al., Appl Catal B 2016, 198, 162–170; Choi et al., Phys Chem Chem Phys 2014, 16(17), 7959–7968; Esteruelas et al., Inorg Chem 2016, 55(14), 7176–7181; Park et al., Int J Hydrogen Energy 2015, 40(46), 16316–16322; Rakap, Appl Catal B 2015, 163, 129–134; Tonbul et al., Int J Hydrogen Energy 2016, 41(26), 11154–11162; Zhang et al., Int J Hydrogen Energy 2016, 41(39), 17208–17215). The paper describes the development of a kinetic model for synthesis of ammonia borane by using borohydride (NaBH₄) and ammonium salt (NH₄)₂SO₄. The synthesis of AB experiments was carried out at different temperature ranges between 25 and 50°C, different inlet molar ratios (NaBH₄/(NH₄)₂SO₄ = 1–4), and different molarities with respect to NaBH₄ (0.11–0.67 M NaBH₄). After the parametric experiments were conducted, empirical power law was evaluated for the synthesis reaction. The power‐law model represented the trends of the kinetics of the synthesis reaction and was reproduced as .