Preparation of spiro-type quaternary ammonium salt via economical and efficient synthetic route as electrolyte for electric double-layer capacitor

A spiro-type quaternary ammonium salt, spiro-(1,1′)-bipyrrolidinium tetrafluoroborate(SBP-BF4) was successfully prepared by an economical and efficient three-step process comprising the cyclization reaction of 1,4-dibromobutane and pyrrolidine, and subsequent ion exchange pathway with KOH followed by neutralization reaction via HBF4 in the system of ethanol solution. 1H NMR, 13 C NMR, FI-IR and XPS analyses showed the structure of SBP-BF4. The as-obtained SBP-BF4 was dissolved in AN and used as the electrolyte for supercapacitor. Electrochemical measurements demonstrate that, compared with commercial electrolyte TEMA-BF4/AN, SBP-BF4/AN exhibits high ionic conductivity, lower resistance and improved cycling performance, which is due to its smaller ion size and stable symmetry structure.

Anode material NbO for Li-ion battery and its electrochemical properties

The NbO electrode materials were successfully synthesized by high-temperature solid-phase method using Nb powders and Nb2O5 powders as raw materials. The crystalline structure, morphology, and electrochemical properties of the obtained materials were characterized by X-ray diffi＇action （XRD）, scanning electron microscopy （SEM）, dynamic light scattering instrument （DLSA）, half- cell charge-discharge tests, and cyclic voltammetry （CV）. The reaction mechanism of lithium with NbO was inves- tigated by ex-situ XRD studies. The results show that material average Li storage voltage is nearly located at 1.6 V, and the lithium intercalation into NbO remains a single-phase process. For the first discharge, a capacity of 355 mAh·g^-1 is obtained at a current rate of 0.1C, and 293 mAh·g^-1is maintained after 50 cycles, whereas a capacity of 416 mAh·g^-1 is obtained at a current rate of 0.1C alter ball milling. And 380 mAh·g^-1 reversible capacity remains for the ball milling sample.

二氟草酸硼酸锂(LiODFB)的制备及其在碳酸二甲酯中的相图和离子缔合规律（英文）

本文介绍了一种新型两步合成法合成二氟草酸硼酸锂,简化了LiODFB的重结晶分离过程。通过NMR、ICP-AES以及卡尔费休法测定所制备的Li ODFB的纯度,结果表明,制备的LiODFB纯度高达99.95%,所含金属离子及水分均得到了很好的控制。此外,采用FTIR、Raman和DSC-TGA分析了LiODFB的结构信息及热力学性质,发现LiODFB具有非常优异的热力学稳定性和较低的水分敏感性,并且其结构信息与文献报道一致。另外,结合相图以及拉曼光谱技术研究了LiODFB-DMC二元体系的热力学相转变和离子规律,用来指导优化LiODFB的合成及重结晶工艺。结果表明,尽管在LiODFB-DMC二元体系中存在3种类型的分子间相互作用形式(CIPs,AGG-Ⅱa,AGG-Ⅲb),但受成核动力学条件影响,LiODFB仅可以通过缓慢冷却的方式获得较大的单晶溶剂化物—LiODFB·(DMC)_(3/2)。本文所提供的基础数据有助于推动LiODFB在锂离子电池领域的应用。

Electrochemical performance of Al_2O_3 pre-coated spinel LiMn_2O_4

Al_2O_3-coated spinel LiMn_2O_4 cathode materials, presintered LiMn_2O_4(P-LMO), and calcined LiMn_2O_4(C-LMO) were synthesized by chemical deposition and thermal treating method using presintered and calcined LiMn_2O_4 as precursors. The crystal structure, morphology,the thickness of the coating layer, and particle size of prepared samples were investigated by X-ray diffraction(XRD), scanning electron microscopy(SEM), high-resolution transmission electron microscopy(HRTEM), and Malvern instruments. The average particle size of P-LMO with like-spheres(0.3 μm) is much smaller than that of C-LMO(0.5 μm). The Al_2O_3 layer of P-LMO can effectively reduce the charge transfer resistance and inhibit the Mn dissolution. The electrochemical performance of P-LMO is better than that of C-LMO. It is found that the LiMn_2O_4 cathode materials have excellent electrochemical cyclability by coated 2 mol% Al_2O_3 at the surface of presintered material. The initial discharge capacity of the material with 2 mol% Al_2O_3-coated is 114.0 m Ah·g^(-1) at 0.1 C rate and 55 ℃, and the capacity retention is 87.3 % at 0.5 C rate.

Preparation,Thermal Stability and Electrochemical Properties of LiODFB

Lithium oxalyldifluoroborate （LiODFB） was synthesized in dimethyl carbonate solvent and purified by the method of solvent-out crystallization. The structure characterization and thermal stability of LiODFB were performed by Fourier transform infrared （FTIR） spectrometry, nuclear magnetic resonance （NMR） spectrometry and thermogravimetric analyzer （TGA）. LiODFB was exposed to 50% humid air at 25 ℃for different time, then dried at 80 ℃ for 12 h, and the electrochemical properties of the cells using 1 mol/L dried LiODFB in ethylene carbonate -I- dimethyl carbonate ＋ ethyl（methyl）carbonate were investigated. The results showed that, pure crystallization LiODFB was obtained; it had good thermal stability with a thermal decomposition temperature of 248 ℃; when it was exposed to humid air, it was firstly converted into LiODFB.H20; with increasing exposure time, more and stronger impurity peaks in the X-ray diffraction （XRD） patterns of LiODFB were observed, and both the discharge specific capacity and the capacity retention decreased gradually.

Corrosion and wear resistance behaviors of electroless Ni-Cu-P-TiN composite coating

Composite coating of Ni-Cu-P alloys containing TiN particles was prepared by electroless technique based on the excellent wear resistance of TiN and better anti-corrosion property of electroless Ni-Cu-P alloys on carbon steel surfaces.Electrochemical method which uses Tafel polarization curves was carried out to study the corrosion performance of the coating.The results indicate that the anti-corrosion ability of the Ni-Cu-P-TiN composite coating(7.92 μA) is almost doubled compared with that of the as-coated Ni-P(13.60 μA).Furthermore,heat treatment results in first increase and then decrease in anticorrosion ability.And the Ni-Cu-P-TiN composite coatings heat-treated for 40 min have maximum hardness of HV 960 and a self-corrosion current of 28.20 μA.The friction coefficient of electroless composite coatings was measured by end-facing tribometer.It is found that the friction coefficient of the Ni-Cu-P-TiN composite coating decreases apparently compared with those of Ni-P and Ni-Cu-P electroless coatings.