电解液对锂离子电池性能的影响

锂离子电池的性能与电解液有着密切的关系。电解液的组成主要是:有机溶剂、锂盐、添加剂。本文综述了电解液组成对锂离子电池电化学性能的影响规律;探讨了电解液量对锂离子电池性能的影响以及不同正极材料锂离子电池对电解液量的需求。     

1,2,3-三氟苯作为电解液添加剂的研究

电解液被称为锂离子电池的"血液",起到运输锂离子的重要作用,对锂电池的性能有重要影响,其中添加剂是电解液的重要组成,不同添加剂对电池的性能有不同的影响。本文针对1,2,3-三氟苯作为电解液添加剂进行了研究,分析了其对电池综合性能的影响。     

电解液PS含量对锂离子电池性能的影响

考察了电解液中PS添加剂含量对锂离子电池初始容量及内阻、高温储存性能、倍率性能、常温循环性能的影响。电解液中PS添加剂含量对于电池初始容量及内阻影响不大。电解液中PS添加剂含量越高,电池的高温储存性能越好。而随着电解液中PS添加剂含量的增加,电池的倍率性能和常温循环性能均有所下降。综合考虑,电解液中PS添加剂含量为1%时,电池性能较优。     

有机电解液在锂离子电池中的充放电机理

讨论了锂离子电池充放电过程中有机电解液的电化学行为,研究发现,有机电解液会在电极活性材料表面发生电化学反应而形成聚合物钝化层(SEI膜),其厚度和疏密性与电解液的组成及充放电制度有关;其组成和电化学性能还将直接影响锂离子电池的充放电容量和循环寿命。通过改变电解液的导电锂盐成分、有机溶剂组成和加入极性添加剂等方法可优化电解液的电化学特性,从而可有效控制该钝化层的成膜过程、膜组成与膜结构,提高锂离子电池的充放电及循环性能。     

锂离子电池安全添加剂的研究进展

锂离子电池具有高能量密度和良好的循环性能,是目前最为理想的动力电源储能体系。然而,由于大容量和高功率锂离子电池技术尚未成熟,存在安全隐患,导致其商业化应用受到了很大程度的限制。锂离子电池的安全问题主要有机械力破坏、异常充电、气体积聚和热失控等,本文分析了上述危险因素产生的原因以及抑制的方法。在这些增强电池安全性的方法中,使用安全添加剂是最为经济有效的手段,但要在电解液中找到一种对电池具有高安全性能且不牺牲其他性能的实用添加剂并不容易,未来同时具备多功能的添加剂将会是对电池性能提升最有希望的研究方向。本文分析了成膜添加剂、阻燃添加剂和防过充添加剂的作用机理,并对相关领域的发展方向进行了展望。     

二氟磷酸锂制备研究进展

二氟磷酸锂是一种在锂离子电池电解液中具有优异性能表现的功能添加剂,可以在锂离子电池的正负极表面形成低阻抗的界面膜,抑制电极与电解液之间的副反应,提高电池的循环寿命。对近年来二氟磷酸锂的合成工艺研究进展进行了回顾,并对各技术方案的特点进行总结。     

添加不同矿物的电解液对锂离子电池性能影响研究

研究了钠长石、滑石、蛭石作为电解液添加剂对锂离子电池性能影响,结果表明,滑石、蛭石矿物对锂离子电池的放电倍率、循环性能、稳定性等方面具有促进作用,而钠长石作用不明显。     

复合添加剂对钒电池正极电解液性能的影响

为了提高钒电池电解液的性能，选取了3种复合添加剂，研究了复合添加剂对钒电池正极电解液稳定性和电化学性能的影响。利用电化学方法制备了2 mol/L的全钒液流电池正极5价钒离子电解液，采用临界胶束浓度法得到复合添加剂的配比为：1% KHSO₄+3 mmol/L SDBS（十二烷基苯磺酸钠）、1% KHSO₄+2 mmol/L D-山梨醇、1% KHSO₄+2 mmol/L CTAB（十六烷基三甲基溴化铵），并考察添加剂加入电解液后的稳定性与电化学性能。通过XRD分析手段，对电解液沉淀物的成分进行了表征。研究表明：添加剂的加入，并不会引起钒离子价态的变化，1% KHSO₄+2 mmol/L CTAB加入后，电解液峰电位差减小12 mV，峰电流增加9.8 mA，说明CTAB与KHSO₄在合适配比下，能够有效提高正极电解液的稳定性及可逆性，添加剂的引入并未引起电解液沉淀物的物相组成变化，电解液性能显著提高。     

锂离子电池高压电解液研究进展

传统碳酸酯类电解液在高压(4.3V,vs.Li/Li~+)下易发生氧化分解反应,导致锂离子电池不可逆容量增加、循环性能下降.为解决这一问题,需从理论和实验两方面对电解液溶剂、锂盐、添加剂及其基本组成等进行针对性设计.耐高压溶剂是提升电解液稳定性的关键因素之一,既经济又有效,添加高浓锂盐是近年来研究较多的可提升电解液电化学窗口和循环稳定性的新策略.本工作从耐高压溶剂、高压添加剂和高浓锂盐三方面综述了近几年锂离子电池高压电解液的研究进展.     

锂离子二次电池电解液研究进展

电解液是锂离子电池的重要组成部分,对电池的许多性能如循环性能、安全性能等有着重要的影响。对近年来国内外涉及电解质盐及有机溶剂的最新研究成果进行了总结和分析。从电解液材料和电解液添加剂的阻燃性能两个角度对锂离子电池材料的安全性能研究进展进行综述,介绍了辅助溶剂的改良和阻燃添加剂的研究状况。     

Electrochemical tuning of titania nanotube morphology in inhibitor electrolytes

The electrochemical behavior of fluorine containing electrolytes and its influence in controlling the lateral dimensions of TiO₂ nanotubes is thoroughly investigated. Potentiostatic anodization is carried out in three different electrolytes, viz., aqueous hydrofluoric acid (HF), HF containing dimethyl sulphoxide (DMSO) and HF containing ethylene glycol (EG). The experiments were carried out over a broad voltage range from 2 to 200 V in 0.1-48 wt% HF concentrations and different electrolytic compositions for anodization times ranging from 5 s to 70 h. The chemistry that dictates how the nature of electrolytes influences the morphology of nanotubes is discussed. Electrochemical impedance spectra were recorded for varying compositions of all the electrolytes. It was observed that composition of the electrolyte and its fluorine inhibiting nature has significant impact on nanotube formation as well as in controlling the aspect ratio. The inhibiting nature of EG is helpful in holding fluorine at the titanium anode, thereby allowing controlled etching at appropriate voltages. Thus our study demonstrates that HF containing EG is a promising electrolytic system providing wide tunability in lateral dimensions and aspect ratio of TiO₂ nanotubes by systematically varying the anodization voltage and electrolyte composition.     

Characterization of Some Poly(Acrylonitrile)-Based Gel Electrolytes

A series of poly(acrylonitrile)-based gel electrolytes was synthesized using poly(acrylonitrile) (PAN), propylene carbonate (PC), and ethylene carbonate (EC) mixtures with different ratios of them for a group of alkali metal salts over a range of concentrations. The electrolytes were characterized in the present article. The conductivity of electrolytes reached values of the order of 10^-3S/cm at ambient temperature and varied with salt, solvent, and PAN content. The composition for a gel electrolyte with good properties was [PC]:[EC]:[PAN]:[salt] = 1.00:1.16:0.63:0.24 (mole ratio). The conduction behavior of the electrolytes is similar to that of solution electrolytes and conductivities were found to follow an Arrhenius law.     

铝合金在不同溶液中的微弧氧化膜层性能研究

分析了ＬＹ１２铝合金在不同电解质溶液生成的微弧氧化膜,比较了微弧氧化膜厚度在不同溶液中随时间的变化。通过扫描电镜和电子探针分析微弧氧化膜的横截面结构,化学成分以及这些元素在微弧氧化膜载面不同位置的分布。实验结果表明微弧氧化膜的生长速度在不同溶液中各个同,但厚度随时间的变化规律基本相同。     

高镍锂离子电池三元材料NCM电解质的应用

高镍三元正极材料成本低、比容量高,符合锂离子电池可持续发展的理念,被认为是下一代的主流正极材料。但是,高镍材料需搭配合适的电解质才能有效发挥其性能,而这一研究很少被关注。因此,总结并选择适配的电解质对于高镍锂离子电池来说格外重要。本文简述了锂离子电池电解质的一般组成及其产生的电解质类型,重点综述了有机液体电解质、固体电解质及离子液体基电解质在高镍三元材料电池中的应用,并通过电解质的量化计算进行了验证总结。分析表明,离子液体-有机溶剂混合电解质在高镍三元材料（NCM）电池中具备更好的循环效果,同时满足了电池安全稳定的要求,更适合作为高镍材料电池的电解质。最后,针对混合电解质各溶剂间的相互作用机理及Li⁺传输等分子动力学研究进行了展望。     

Targeted synthesis of octacalcium phosphate and a study of its properties

The optimal conditions of synthesis of one of the most promising precursors of biological apatites— octacalcium phosphate (OCP)—have been determined. The OCP synthesis was carried out by two main methods: hydrolysis of brushite and precipitation from an aqueous solution. The samples’ phase composition, morphology, and thermal stability, as well as their bioresorbability in electrolytes of different acidity, have been investigated.     

Experimental and theoretical analysis of a thermogalvanic undivided flow cell with two aqueous electrolytes at different temperatures

The electrochemical and thermal performance of a new thermogalvanic undivided flow cell using two aqueous electrolytes maintained at different temperatures between platinum electrodes is described. Measurements on the Fe(CN) ₆ ^3– /Fe(CN) ₆ ^4– redox system in NaOH medium yield a thermoelectric effect between –1.1 and –1.4mV/degree depending on the composition of the electrolytes. The influence of different parameters (temperature gradient, concentration of the electroactive species, fluid velocities and channel thickness) on the power output are determined. The experimental results show that electrical power is largely limited by charge and mass transfer overvoltages, but that it is possible to maintain the temperature gradient between the electrodes, i.e. the thermal boundary layers developing at the interface between the electrolytes do not reach the electrodes. A model based on the generalized Butler-Volmer kinetic equation is found to be in very good agreement with the experiments in terms of the current-voltage relationship and power output. This model is used for the prediction of the maximum electrochemical performance. From a practical point of view the efficiency of these devices remains very low due to the high thermal flux between the hot and cold electrolytes.     

Electrocatalytic oxygen reduction on single-walled carbon nanotubes supported Pt alloys nanoparticles in acidic and alkaline conditions

The objective of this study is to improve the catalytic activity of platinum by alloying with transition metal (Pd) in gas diffusion electrodes (GDEs) by oxygen reduction reaction (ORR) at cathode site and comparison of the acidic and alkaline electrolytes. The high porosity of single-walled carbon nanotubes (SWCNTs) facilitates diffusion of the reactant and facilitates interaction with the Pt surface. It is also evident that SWCNTs enhance the stability of the electrocatalyst. Functionalized SWCNTs are used as a means to facilitate the uniform deposition of Pt on the SWCNT surface. The structure of SWCNTs is nearly perfect, even after functionalization, while other types of CNTs contain a significant concentration of structural defects in their walls. So catalysts supported on SWCNTs are studied in this research. The electrocatalytic properties of ORR were evaluated by cyclic voltammetry, polarization experiments, and chronoamperometry. The morphology and elemental composition of Pt alloys were characterized by X-ray diffraction (XRD) analysis and inductively coupled plasma atomic emission spectroscopy (ICP-AES) system. The catalytic activities of the bimetallic catalysts in GDEs have been shown to be not only dependent on the composition, but also on the nature of the electrolytes. The GDEs have shown a transition from the slow ORR kinetics in alkaline electrolyte to the fast ORR kinetics in the acidic electrolyte. The results also show that introduction of Pd as transition metal in the Pt alloys provides fast ORR kinetics in both acidic and alkaline electrolytes. The performance of GDEs with Pt–Pd alloy surfaces towards the ORR as a function of the alloy’s overall composition and their behavior in acidic electrolyte was also studied. These results show that the alloy’s overall composition and also the nature of the electrolytes have a large effect on the performance of GDEs for ORR.     

Electrodeposition of aluminium-copper alloys from alkyl benzene electrolytes

An experimental programme in which aluminium-copper alloys were electroplated from alkyl benzene/ AlBr₃ electrolytes is described. The investigation showed that Al-Cu alloys (0–3.5 wt% Cu) can be plated onto steel and that the resulting coatings are bright, adherent and less porous than equivalent coatings of pure aluminium. The composition of the cathode deposits can be readily controlled by using Al-Cu anodes of specified copper content. About half the copper dissolved from the anodes is transferred to the cathode, the remainder being precipitated from the electrolyte as CuBr. Coating composition varies with current density and this parameter can also be used to control the process. In a parallel investigation, potential differences between aluminium and a number of other metals (Zn, Pb, Cd, Sn, Cu, Ag) were measured. Potential differences in the alkyl benzene electrolytes were found to be 10–30 times less than in aqueous electrolytes which indicates that the alkyl benzenes should be useful for plating other alloys in addition to those of aluminium and copper.     

Membrane potential and fixed-charge density across TiPO4–VPO4 composite membranes for uni-univalent electrolyte solution

The TVP composite membranes were prepared by sol–gel process, and the membrane potential has been measured for characterizing the ion-transport phenomena across a charged membrane using electrolytes (KCl, NaCl and LiCl). The membrane potential offered by the electrolytes is in the order of LiCl > NaCl > KCl, and the membrane is found to be cation-selective. The results have been used to estimate fixed-charge density, distribution coefficient, charge effectiveness and transport properties of electrolytes of this membrane. The fixed-charge density is the most important parameter, governing transport phenomena in membranes. It is estimated by the TMS method; it is dependent on the feed composition due to the prefential adsorption of some ions. The results indicate that the applied pressure is also an important variable to modify the charge density and, in turn, the performance of membrane. The order of charge effectiveness of the electrolytes in membrane depends on the ionic radii of the counter-ions. The experimental results for membrane potential are quite consistent with the theoretical prediction. The morphology of the membrane surface is studied by scanning electron micrographs (SEM).     

Influence of Zn2+ ions on copper electrowinning from sulfate electrolytes

During electrowinning of copper from wastes, it was observed that Zn2+ impurities had some effects on the aspect of the deposits although the codeposition of these two metals is impossible under normal conditions. Cyclic voltammetry, impedance analysis and rotating disc electrode techniques were used to characterize the effect of the presence of small amounts of Zn2+ on the copper electrodeposition kinetics from acidic sulphate electrolytes. SEM and X-ray diffraction analysis were used to determine the morphology and the structure of the copper deposits. Their composition was determined using X-ray dispersive analysis. The addition of small amounts of Zn2+ had no effect, either on the crystal growth orientation of the copper deposits, or on their composition, but it modified slightly their morphology by increasing their microscopic roughness. An increase in the cathodic peak of the cyclic voltammograms observed in the presence of Zn2+ can be attributed to the higher roughness of the copper deposits. From impedance analysis, it can be deduced that Zn2+ ions are electrosorbed at the interface and have an effect on the copper electrodeposition kinetics. The adsorption capacitance, Ca, was calculated and correlated with the Zn2+ concentration. It was found that the nucleation time constant, parameter influenced by the growing mode of the deposit, decreased in the presence of Zn2+, especially at low concentrations.