Lithium electrochemistry of NiSe2: A new kind of storage energy material

NiSe₂ thin film has been successfully fabricated by reactive pulsed laser deposition and was investigated for its electrochemistry with lithium for the first time. The reversible discharge capacities of NiSe₂/Li cells cycled between 1.0 V and 3.0 V were found in the range of 314.9–467.5 mA h g⁻¹ during the first 200 cycles. By using ex situ X-ray diffraction, transmission electron microscopy, and selected-area electron diffraction measurements, the intermediates of β-NiSe, and Ni₃Se₂ were identified during the reversible conversions of NiSe₂ into metal nickel and Li₂Se. Both cation (nickel) and anion (selenium) in NiSe₂ provide the redox active centers in its electrochemical reaction with lithium, indicating one of the features of its lithium electrochemistry. The high reversible capacity and good cycle ability of NiSe₂ electrode made it become a promising cathode material for future rechargeable lithium batteries.     

电阻应变法用于密封电池内压变化的动态检测

报道了采用电阻变法动态检测密封电池内压变化的实验方法，并以镍氢电池为例，介绍了这一方法在研究电池工艺技术条件与电池充放电性能关系时的具体应用。     

A novel PEO-based composite solid-state polymer electrolyte with methyl group-functionalized SBA-15 filler for rechargeable lithium batteries

Functionalized molecular sieve SBA-15 with trimethylchlorosilane was used as an inorganic filler in a poly(ethyleneoxide) (PEO) polymer matrix to synthesize a composite solid-state polymer electrolyte (CSPE) using LiClO₄ as the doping salts, which is designated to be used for rechargeable lithium batteries. The methyl group-functionalized SBA-15 (^fSBA-15) powder possesses more hydrophobic characters than SBA-15, which improves the miscibility between the ^fSBA-15 filler and the PEO matrix. The interaction between the ^fSBA-15 and PEO polymer matrix was investigated by scanning electron microscopy, X-ray diffraction, and differential scanning calorimetry. Linear sweep voltammetry and electrochemical impedance spectroscopy were employed to study the electrochemical stability windows, ionic conductivity, and interfacial stability of the CSPE. The temperature dependence of the change of the PEO polymer matrix in the CSPE from crystallization to amorphous phase was surveyed, for the first time, at different temperature by Fourier transform infrared emission spectroscopy. It has demonstrated that the addition of the ^fSBA-15 filler has improved significantly the electrochemical compatibility of the CSPE with a lithium metal electrode and enhanced effectively the ion conductivity of the CSPE. Dedicated to Professor Oleg Petrii on the occasion of his 70th birthday on August 24th, 2007.     

Preparation and characterization of aqueous polyaniline battery using a modified polyaniline electrode

A rechargeable battery of the type Zn/ZnCl₂, NH₄Cl/polyaniline (PAn)-reticulated vitreous carbon was successfully prepared based on a PAn modified electrode. Voltage of the battery was 1.2 V. Charge-discharge behavior at a constant load of 2.5 k, recycle ability and the rate of self-discharge were measured. The results showed that the battery has a capacity of 121 mA h g⁻¹ polymer weight and coulombic efficiency was in the range between 75% and 100%. Self-discharge rate was less than 1% per day and the battery showed a good recycle ability. It was also found that even after 70 cycles, the decrease in the open-circuit voltage was less than 5%.     

吡唑基镁卤化物/四氢呋喃可充镁电池电解液

将不同配比的吡唑与格氏试剂反应制得的吡唑基镁卤化物/四氢呋喃（THF）溶液用作可充镁电池电解液,采用循环伏安和恒电流充放电测试研究了该电解液的镁沉积-溶出性能和氧化分解电位;并通过X射线衍射（XRD）和扫描电镜（SEM）对沉积物的组分和形貌进行了分析. 结果表明,吡唑上的取代基、吡唑与格氏试剂的反应配比对电解液的电化学性能都有影响. 1 mol·L^-1 1-甲基吡唑-PhMgCl（1：1摩尔比）/THF反应配制的电解液在不锈钢（SS）集流体的阳极氧化分解电位达到2.4 V（vs Mg/Mg²⁺）,并具有镁沉积-溶出电位低、循环稳定性高、配制方便的特点,有希望应用于实际的可充镁电池体系中.     

PEO基纳米复合聚合物电解质电化学性质的研究

以PEO8 LiClO4作母体,纳米SiO2为填料,制成PEO8 LiClO4 SiO2(x%)系列复合聚合物电解质,测定这该电解质的电导率、锂离子迁移数和电化学稳定窗口,并对其晶态结构作差热分析表征.结果表明,纳米SiO2的引入,显著提高了电解质的电导率,在22℃时达到4.3×10-5S·cm-1.此外,还探讨了填料对复合聚合物电解质电导率提高的影响机理.     

Influence of structural defects on the insertion behavior of γ-MnO2: comparison of H and Li

In an attempt to correlate the crystallographic disorder of γ-MnO₂ compounds to their cationic uptake, the influence of their structural defects on their lithium and proton insertion behavior has been studied and compared. The rate of structural defects in the starting γ-MnO₂ compounds strongly modifies both the voltage vs. cation composition profiles (in terms of shape, average voltage of each electrochemical process, polarization and cycled capacity) and the cycling behavior during the first cycles. This work illustrates that the relationships between structure and cation insertion behavior are different for Li and for proton. The study allows to select for better performing samples in terms of maximum cycled capacity: Li insertion is favored by a very small amount of initial disorder (i.e. a low rate of structural defects in starting compound), while proton insertion requires maximum initial disorder (i.e. an intermediate rate of structural defects). Extrapolation of the results demonstrates the interest of Ramsdellite γ-MnO₂ compounds for cathode applications of rechargeable Li batteries.     

Synthesis of lithium-manganese oxide spinel in hydrothermal conditions

Abstract

Lithium-manganese oxide spinel LiMn₂O₄ was synthesized in hydrothermal conditions (400°C, 20 MPa) in the course of thermovaporous treatment mixtures of MnO₂ and LiOH/or Li₂CO₃. The conditions of synthesis of the spinel as monophase product were determined. The obtained product has been characterized by means of various physical and chemical methods. The spinel has been used for manufacturing cathodes of rechargeable lithium cells. The cells discharged in the potential range 2.8-3.5 V. The specific capacity was 100-140mAh/g.     

苯硫酚盐基溶液的可充镁电池电解液

将4-甲基苯硫酚、4-异丙基苯硫酚和4-甲氧基苯硫酚(RSH)分别与格氏试剂C₂H₅MgCl/THF(四氢呋喃)反应制得的苯硫酚氯化镁(RSMgCl)(分别标记为MBMC、IPBMC和MOBMC)/THF和进一步与Lewis 酸AlCl₃反应制得的(RSMgCl)_n-AlCl₃/THF(n=1,1.5,2)苯硫酚盐基溶液用作可充镁电池电解液,采用循环伏安和恒电流充放电测试研究了电解液的镁沉积-溶出性能和氧化分解电位. 结果表明,苯硫酚上的基团种类和RSMgCl与AlCl₃的比例对其电化学性能有影响. 其中,0.5 mol·L^-1(IPBMC)_1.5-AlCl₃/THF 溶液具有最佳的电化学性能,其氧化分解电位适宜(2.4 V(vs Mg/Mg²⁺)),镁沉积-溶出循环效率稳定,过电位低,电导率较高(2.48 mS·cm^-1),与正极材料Mo₆S₈兼容性良好,且具有一定的空气稳定性,配制方便,有希望应用于实际的可充镁电池体系中.     

Corrosion crack enhancement during the cathodic activation of zirconium AB<Subscript>2</Subscript> alloys

The activation of zirconium nickel alloys with and without the addition of chromium and titanium is investigated through electrochemical and optical techniques. Recent investigations in aqueous 1 M KOH indicate oxide layer growth and occlusion of hydrogen species in the alloys during the application of different cathodic scan potential programmes currently used for the activation process. In this research, several techniques, such as voltammetry, ellipsometry, energy dispersive analysis of X-rays and scanning electron microscopy, are applied to three polished massive alloys, Zr_1−x Ni _x , x = 0.36 and 0.43, and Zr_0.9Ti_0.1NiCr. Data analysis shows that the stability, compactness and structure of the passive layers are strongly dependent on the applied potential programme. The alloy activation depends on the formation of deep crevices that remain after further polishing. The microscopic observation shows an increase in crevice thickness after cathodic sweep potential cycling, which produces fragmentation of the grains and oxide growth during the activation process. This indicates metal breaking and intergranular alloy dissolution that take place together with oxide and hydride formation. In some cases, the resultant crevice thickness is one or two orders higher than the growth of surface oxide indicating localised intergranular corrosion. Dedicated to Prof. Dr. Teresa Iwasita on the occasion of her 65th birthday in recognition of her numerous contributions to interfacial electrochemistry.