Propylene sulfite as film-forming electrolyte additive in lithium ion batteries

Propylene sulfite (PS) has been studied as a film-forming electrolyte additive for use in lithium ion battery electrolytes. Even small amounts in the order of 5 vol.% PS suppress propylene carbonate (PC) co-intercalation into graphite. In addition, a 1 M LiClO₄/PC/PS (95:5 by volume) electrolyte is characterised by a high oxidation stability at a LiMn₂O₄ cathode.     

GBL-based electrolyte for Li-ion battery: thermal and electrochemical performance

Thermal stability, flammability, and electrochemical performances of the cyclic carbonate-based electrolytes [where γ-butyrolactone (GBL) is a main component (at least 50 vol.%) among of EC and PC with LiBF₄] have been examined in comparison with contemporary (EC/EMC, 1:3 vol.%, 1 M LiPF₆) electrolyte by DSC, accelerating rate calorimetry (ARC), AC impedance, and cyclic voltammetry (CV). This study shows that GBL-based electrolytes have perfect thermal stability and will improve Li-ion battery safety (including flammability) without performance trade-off with the accurate combination of active materials and separator. Several types of negative electrode materials (such as hard carbon, MCMB, and SWF) have been tested to evaluate GBL-based electrolyte influence on SEI formation and battery performance. Finally, GBL-based electrolytes show not only equal electrochemical performance in comparison to commonly used electrolytes (EC/EMC in this study) but it will notably improve battery safety.     

亚磷酸三甲酯作为锂离子电池电解液溶剂的研究

为了提高锂离子电池电解液的热稳定性,使用亚磷酸三甲酯TMP作为溶剂来配置锂离子电池电解液,研究该电解液燃烧性能、电化学性能和热稳定性,并与商业用电解液作了比较.循环性能测试结果表明,亚磷酸三甲酯基电解液与正极材料LiNg0.8Co0.2O2有很好的相容性,有良好的电化学稳定性,而且与PC组成电解液时可一定程度地抑制PC对负极石墨材料的剥离.燃烧试验和微量量热实验表明,TMP的加入能显著地提高电解液的热稳定性与安全性能.     

二氟二草酸硼酸锂对LiFePO4/石墨电池高温性能的影响

研究了二氟二草酸硼酸锂(LiODFB)作为锂盐加入到碳酸丙烯酯(PC)+碳酸乙烯酯(EC)+碳酸甲乙酯(EMC)(质量比为1:1:3)混合溶剂中对LiFePO4/石墨电池高温(60 ℃)循环性能的影响. 用线性扫描伏安法(LSV)测试了电解液的电化学窗口. 通过等离子发射光谱(ICP)和能量散射光谱(EDS)对LiFePO4材料高温条件下在不同电解液中的稳定性进行了研究; 并用扫描电镜(SEM)和电化学交流阻抗谱(EIS)分析了石墨负极表面的固体电解液相界面(SEI)膜的热稳定性. 结果表明: 一方面LiODFB基电解液能抑制LiFePO4材料在高温条件下Fe(II)的溶解, 防止溶解的Fe(II)在石墨上还原, 有效地降低电池阻抗; 另一方面, 在LiODFB基电解液中形成的石墨负极表面SEI膜具有更好的热稳定性, 能显著提高LiFePO4/石墨电池的高温循环性能.     

A novel approach for the determination of paracetamol based on the reduction of N-acetyl-p-benzoquinoneimine formed on the electrochemically treated pencil graphite electrode

A novel approach was proposed for the simple and rapid electrochemical determination of paracetamol (PC) in the presence of uric acid in body fluids. The voltammetric determination of PC is based on the electrochemical reduction of N-acetyl-p-benzoquinoneimine formed simultaneously on the electrochemically treated pencil graphite (ETPG) electrode during the measurement. ETPG electrodes were prepared by the potential cycling between −0.3 V and +2.0 V in 0.1 M H₃PO₄ solution. The electrochemical performance of the ETPG electrode was evaluated by adsorptive transfer stripping differential pulse voltammetry (ATSDPV). The resulting sensor showed good performance for the determination of PC in human blood serum samples with a linear range of 0.05–2.5 μM and a highly reproducible response (RSD of 3.1%). The calculated detection limit was 2.5 nM (S/N = 3). The proposed method does not require any sample pretreatment, prevents the interference of uric acid and allows the determination of PC directly in blood serum samples.     

温度对石墨电极性能的影响

运用电化学阻抗谱(EIS)并结合循环伏安法(CV)研究了石墨电极25和60 ℃时在1 mol·L-1 LiPF6-EC(碳酸乙烯酯):DEC(碳酸二乙酯):DMC(碳酸二甲酯)电解液中, 以及60 ℃时在1 mol·L-1 LiPF6-EC:DEC:DMC+5%VC(碳酸亚乙烯酯)电解液中的首次阴极极化过程. 发现高温下(60 ℃)石墨电极在1 mol·L-1 LiPF6-EC:DEC:DMC电解液中可逆循环容量衰减的主要原因在于其表面无法形成稳定的固体电解质相界面(SEI)膜. 实验结果显示, VC添加剂能够增进高温下石墨电极表面SEI膜的稳定性, 进而改进石墨电极的循环性能.     

Electropolymerization of 3-methylthiophene at liquid 3-methylthiophene | aqueous solution | graphite three-phase junction

Droplets of 3-methylthiophene are mechanically attached to the surface of paraffin-impregnated graphite electrode (PIGE) and immersed into aqueous solution of LiClO₄. It is demonstrated that the oxidative electropolymerization (observed in non-aqueous solutions) can be accomplished by potential cycling between −0.3 and 1.4 V vs. saturated calomel electrode (SCE). Since the droplets do not contain a dissolved electrolyte, the electrochemical reaction starts at the very edge of the three-phase junction organic droplet | graphite | aqueous electrolyte.     

Li_2CO_3添加剂对石墨电极性能的影响

运用电化学阻抗谱(EIS)和循环伏安法(CV)研究了在1mol/LLiPF6-EC(碳酸乙烯酯):DMC(碳酸二甲酯)电解液中添加Li2CO3对石墨电极性能的影响及机制.CV研究结果表明,在1mol/LLiPF6-EC:DMC电解液中添加Li2CO3能够有效抑制石墨电极首次充放电过程中碳酸乙烯酯(EC)的单电子还原过程,即还原分解产生乙烯和碳酸锂的过程,进而改善石墨电极的电化学循环性能.EIS研究结果表明,在添加Li2CO3的1mol/LLiPF6-EC:DMC电解液中,石墨电极表面的固体电解质相界面膜(SEI膜)具有较强的黏弹性,可以更好地适应锂离子嵌入过程中石墨颗粒体积的微小变化,从而使锂离子的嵌入过程更容易进行.     

Cyclic carbonate based-electrolytes enhancing the electrochemical performance of Na4Fe3(PO4)2(P2O7) cathodes for sodium-ion batteries

Binary solvent mixtures containing NaClO₄ salt were investigated as electrolytes for sodium-ion batteries. The electrochemical performance of Na₄Fe₃(PO₄)₂(P₂O₇) cathodes was substantially improved when paired with an ethylene carbonate (EC)/propylene carbonate (PC)-based electrolyte. Our investigation revealed that EC/PC/1 M NaClO₄ exhibits superior oxidation durability at the cathode and is highly stable toward a Na-metal electrode.     

Effect of mild oxidation of natural graphite (NG7) on anode-electrolyte thermal reactions

The effect of mild oxidation of natural graphite (NG7) and some other parameters on the reaction between a fully lithiated graphite anode (Li _x C₆, x=1.0–1.1) and 1 M lithium hexafluoroarsenate in ethylene carbonate and diethyl carbonate electrolyte (1:2, v/v) were studied by differential scanning calorimetry (DSC). It was found that mild oxidation of the graphite suppressed the exothermic reaction of the fully lithiated anode with the electrolyte, most probably as a result of the formation of a more stable and chemically bonded solid electrolyte interphase. Separation and removal of the small graphite particles from the anode mixture suppressed this reaction further. It was also found that the copper current collector, the amount of electrolyte and binder as well as other parameters have a significant influence on the heat evolution as measured by DSC. Received: 11 October 1999 / Accepted: 1 March 2000     

白藜芦醇对长期贮存锂离子电池电解液性能的影响

锂离子电池电解液从制造完成到使用,一般都会经历灌装、运输和贮存的过程,了解长期贮存过程对锂离子电池电解液性能的影响,对锂离子电池的生产具有一定的理论指导意义.本文运用电化学阻抗谱(EIS)测试并结合循环伏安法(CV)测试、充放电测试、扫描电子显微镜(SEM)等研究了1 mol.L-1 LiPF6-EC:EMC 基础电解...     

Anion receptor-coated separator for lithium-ion polymer battery

Anion receptor-coated separators were prepared by coating poly(ethylene glycol) borate ester (PEGB) as an anion receptor and poly(vinyl acetate) (PVAc) as a good adhesive material towards electrodes onto microporous polyethylene (PE) separators. Gel polymer electrolytes were fabricated by soaking them in an liquid electrolyte, 1 M LiPF₆ in EC/DEC/PC (30/65/5, wt.%). As the weight ratio of PEGB to PVAc in a coating layer increased, gel polymer electrolytes showed higher cationic conductivity and electrochemical stability. The cationic conductivity and electrochemical stability of the gel polymer electrolyte based on coated separator with PVAc/PEGB (2/5, weight ratio) could reach 2.8 × 10^–4 S cm^–1 and 4.8 V, respectively. Lithium-ion polymer cells (LiCoO₂/graphite) based on gel polymer electrolytes with and without PEGB were assembled, and their electrochemical performances were evaluated.     

Electrodeposition of Zr on graphite in molten fluorides

The electrochemical behavior of Zr⁴⁺ using graphite working electrode has been studied in fused LiF–NaF–ZrF₄ eutectic mixture (temperature range 923–1123 K). In addition to the electrochemical profile related to the deposition/dissolution of Zr metal, the cyclic voltammograms exhibit well-defined peaks attributed to the formation of zirconium carbide. A third contribution relative to the formation of Li–graphite intercalation compound and/or lithium carbide was also proposed for a better interpretation of the voltammogram. Depending on the experimental deposition conditions, the analysis of the deposits by SEM/EDX has revealed the presence of a Zr metal thin film with various porosities and compositions. Moreover, the electrochemical reduction of Zr(IV) in molten fluorides using a graphite electrode allows the extraction of pure Zr metal.     

Understanding the electrochemistry of “water-in-salt” electrolytes: basal plane highly ordered pyrolytic graphite as a model system

A new approach to expand the accessible voltage window of electrochemical energy storage systems, based on so-called “water-in-salt” electrolytes, has been expounded recently. Although studies of transport in concentrated electrolytes date back over several decades, the recent demonstration that concentrated aqueous electrolyte systems can be used in the lithium ion battery context has rekindled interest in the electrochemical properties of highly concentrated aqueous electrolytes. The original aqueous lithium ion battery conception was based on the use of concentrated solutions of lithium bis(trifluoromethanesulfonyl)imide, although these electrolytes still possess some drawbacks including cost, toxicity, and safety. In this work we describe the electrochemical behavior of a simple 1 : 1 electrolyte based on highly concentrated aqueous solutions of potassium fluoride (KF). Highly ordered pyrolytic graphite (HOPG) is used as well-defined model carbon to study the electrochemical properties of the electrolyte, as well as its basal plane capacitance, from a microscopic perspective: the KF electrolyte exhibits an unusually wide potential window (up to 2.6 V). The faradaic response on HOPG is also reported using K₃Fe(CN)₆ as a model redox probe: the highly concentrated electrolyte provides good electrochemical reversibility and protects the HOPG surface from adsorption of contaminants. Moreover, this electrolyte was applied to symmetrical supercapacitors (using graphene and activated carbon as active materials) in order to quantify its performance in energy storage applications. It is found that the activated carbon and graphene supercapacitors demonstrate high gravimetric capacitance (221 F g⁻¹ for activated carbon, and 56 F g⁻¹ for graphene), a stable working voltage window of 2.0 V, which is significantly higher than the usual range of water-based capacitors, and excellent stability over 10 000 cycles. These results provide fundamental insight into the wider applicability of highly concentrated electrolytes, which should enable their application in future of energy storage technologies.

The stability of water-in-salt electrolyte systems is investigated using highly concentrated solutions of KF(aq) with graphite as a model system.     

Understanding High-Rate K+-Solvent Co-Intercalation in Natural Graphite for Potassium-Ion Batteries

Graphite shows great potential as an anode material for rechargeable metal-ion batteries because of its high abundance and low cost. However, the electrochemical performance of graphite anode materials for rechargeable potassium-ion batteries needs to be further improved. Reported herein is a natural graphite with superior rate performance and cycling stability obtained through a unique K⁺-solvent co-intercalation mechanism in a 1 m KCF₃SO₃ diethylene glycol dimethyl ether electrolyte. The co-intercalation mechanism was demonstrated by ex situ Fourier transform infrared spectroscopy and in situ X-ray diffraction. Moreover, the structure of the [K-solvent]⁺ complexes intercalated with the graphite and the conditions for reversible K⁺-solvent co-intercalation into graphite are proposed based on the experimental results and first-principles calculations. This work provides important insights into the design of natural graphite for high-performance rechargeable potassium-ion batteries.     

Surface-renewable cobalt(II) hexacyanoferrate-modified graphite organosilicate electrode and its electrocatalytic oxidation of thiosulfate

Cobalt(II) hexacyanoferrate (CoHCF) was deposited on graphite powder by an in situ chemical deposition procedure and then dispersed into methyltrimethoxysilane-derived gels to prepare a surface-renewable CoHCF-modified electrode. The electrochemical behavior of the modified electrode in different supporting electrolyte solutions was characterized by cyclic voltammetry. In addition, square-wave voltammetry was employed to investigate the pNa-dependent electrochemical behavior of the electrode. The CoHCF-modified electrode showed a high electrocatalytic activity toward thiosulfate oxidation and could thus be used as an amperometric thiosulfate sensor.     

铂催化剂在有机电解液中对氨氧化的电催化性能

研究了用碳酸丙烯酯(PC)和低粘度的乙二醇二甲醚(DME)作电流型电化学氨气传感器的有机混合电解液时,氨在碳载Pt(Pt/C)催化剂电极上的电氧化性能.实验表明,Pt/C催化剂电极对氨的氧化有很好的电催化活性,稳定性、选择性和响应时间等参数均良好,而且还能耐高温低湿的条件,可解决水溶液电解液因蒸发而失效的问题,延长了传...     

基于阴离子-石墨嵌层化合物的电化学电容器

石墨可以在高电势下电化学可逆存储阴离子,有望在高电压储能器件中担当正极材料.本文介绍了基于阴离子-石墨嵌层化合物型正极材料的高比能电容器的研究进展,剖析了影响电容器性能的各方面因素,探讨了一系列表征相关电极材料储能机制的方法和手段,揭示了溶剂化效应对阴离子插嵌石墨正极电化学行为的关键性作用.并进一步概述了该种正极材料近年来在新型储能器件-双离子电池中的发展态势,展望了其应用前景和即将面临的潜在问题.     

Electrochemical recognition and trace-level detection of bactericide carbendazim using carboxylic group functionalized poly(3,4-ethylenedioxythiophene) mimic electrode

The electrochemical recognition and trace-level detection of bactericide carbendazim (MBC) in paddy water and commercial juice were realized using carboxylic group functionalized poly(3,4-ethylenedioxythiophene) (PC4-EDOT-COOH) film electrode. PC4-EDOT-COOH film was prepared by one step, low-cost, and green electrosynthesis in aqueous microemulsion system and characterized by FT-IR, cyclic voltammetry, UV–vis and SEM. In comparison with poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(hydroxymethylated-3,4-ethylenedioxylthiophene) (PEDTM), PC4-EDOT-COOH exhibited the best electrochemical recognition towards MBC and the recognition mechanism was proved by quantitative calculation. Sensing parameters such as pH values, accumulation potential, accumulation time, supporting electrolyte, and scan rate on the current response of MBC were discussed. In addition, the sensor can be applied to quantification of MBC in the concentration range of 0.012–0.35 μM with a low detection limit of 3.5 nM (S/N = 3). Moreover, PC4-EDOT-COOH film electrode showed good stability, high selectivity, and satisfactory anti-interference ability. Satisfactory results indicated that PC4-EDOT-COOH film is a promising sensing platform for the trace-level analysis of bactericide residue carbendazim in agricultural crops and environment.     

Electrocatalytic oxidation of reduced nicotinamide coenzymes by graphite electrodes modified with an adsorbed phenoxazinium salt,meldola blue

Meldola Blue (7-dimethylamino-1,2-benzophenoxazine) can be adsorbed on graphite to give chemically modified electrodes. The electrochemical redox reactions of the phenoxazine are fairly reversible at low coverages with an E′^o of ?175 mV vs. SCE at pH 7.0. The electrode was most stable in acid solutions, at pH 6.0 its electrochemical activity decreased by 15% during 2h. The adsorbed compound mediated electron transfer in the electrocatalytic oxidation of the nicotinamide coenzymes (NADH and NADPH). The formation of a charge transfer complex between Meldola Blue and the coenzyme is demonstrated by experiments with a rotating disk electrode. The complex decomposes in a rate limiting step (k₊₂=30 s^?1) to the oxidized coenzyme and the reduced Meldola Blue. The latter can be reoxidized in a fast electrochemical step. The overall result is an electrocatalytic oxidation at a voltage which is about 500 mV lower than at an unmodified electrode.