可充镁电池电解质研究现状

综述了可充镁电池电解质材料的研究进展;介绍了有机格氏试剂盐系列电解质和可传导镁离子的聚合物电解质(GPE);简述了相应的制备工艺和存在的主要问题;最后提出可充镁电池电解质的发展趋势.     

Ionic conductivities of solid polymer electrolyte/salt systems for lithium secondary battery

We establish a new ionic conductivity model based on the Nernst-Einstein equation in which the diffusion coefficient is derived from modified double lattice-nonrandom-Pitzer-Debye-Hückel (MDL-NR-PDH) model. The proposed model takes into account the mobility of the salt and the motion of the polymer host simultaneously by expressing the effective chemical potential as the sum of chemical potentials of the salt and the polymer. To describe the segmental motion of the polymer chain, which is the well-known conduction mechanism for solid polymer electrolyte (SPE) systems, the effective co-ordinated unit parameter is introduced. The obtained co-ordinated unit parameter for each state is used to describe the behavior of the ionic conductivities of the given systems. Good agreement is obtained upon comparison with experimental data of various PEO and salt systems in the interested ranges.     

原位构建富氟SEI的凝胶电解质用于金属锂二次电池

以六氟磷酸锂（LiPF₆）为四氢呋喃的聚合引发剂制备凝胶电解质,同时作为氟源在金属锂负极表面原位构建富含LiF的固态电解质界面层（solid electrolyte interface,SEI）来抑制锂枝晶的生长以及金属锂/电解液之间的副反应。所制备的凝胶电解质具有较高的室温离子电导率（1.33 mS·cm^-1）和较宽的电化学稳定窗口（4.5 V）。原位聚合方式组装金属锂对称电池循环后,锂负极表面没有明显的锂枝晶和被损毁的形貌出现;XPS结果表明锂负极表面生成了富含LiF的SEI。组装的LiFePO₄全电池在1 C的电流密度下,稳定循环400周后仍保持118.7 mAh·g^-1的放电比容量。得益于四氢呋喃在开环聚合反应过程中,促进了LiPF₆分解反应平衡的正向移动,在锂负极表面形成稳定的富含LiF的SEI,能够抑制锂枝晶的生长并防止其被持续性的腐蚀破坏。     

原位构建富氟SEI的凝胶电解质用于金属锂二次电池

以六氟磷酸锂（LiPF₆）为四氢呋喃的聚合引发剂制备凝胶电解质,同时作为氟源在金属锂负极表面原位构建富含LiF的固态电解质界面层（solid electrolyte interface,SEI）来抑制锂枝晶的生长以及金属锂/电解液之间的副反应。所制备的凝胶电解质具有较高的室温离子电导率（1.33 mS·cm^-1）和较宽的电化学稳定窗口（4.5 V）。原位聚合方式组装金属锂对称电池循环后,锂负极表面没有明显的锂枝晶和被损毁的形貌出现;XPS结果表明锂负极表面生成了富含LiF的SEI。组装的LiFePO₄全电池在1 C的电流密度下,稳定循环400周后仍保持118.7 mAh·g^-1的放电比容量。得益于四氢呋喃在开环聚合反应过程中,促进了LiPF₆分解反应平衡的正向移动,在锂负极表面形成稳定的富含LiF的SEI,能够抑制锂枝晶的生长并防止其被持续性的腐蚀破坏。     

Electrochemical properties of Li ion polymer battery with gel polymer electrolyte based on polyurethane

Gel polymer electrolyte (GPE) was prepared using polyurethane acrylate as polymer host and its performance was evaluated. LiCoO₂/GPE/graphite cells were prepared and their electrochemical performance as a function of discharge currents and temperatures was evaluated. The precursor containing a 5 vol % curable mixture had a viscosity of 4.5 mPa s. The ionic conductivity of the GPE at 20 °C was about 4.5 × 10^–3 S cm^–1. The GPE was stable electrochemically up to a potential of 4.8 V vs Li/Li⁺. LiCoO₂/GPE/graphite cells showed a good high rate and low-temperature performance. The discharge capacity of the cell was stable with charge–discharge cycling.     

Gel polymer electrolyte with semi-IPN fabric for polymer lithium-ion battery

A new type of semi-IPN gel electrolyte was prepared by thermal polymerization in this article. At first, the crosslinkable PEG200 (MXPEG) was prepared by condensation reaction, then the crosslinkable components were blent with PMMA and heated under vacuum to form polymer blends with semi-IPN fabric. Differential scanning calorimetry and X-ray diffraction spectroscopy were used to investigate the thermal properties and crystalline/amorphous structure of the prepared polymer blends. With semi-IPN fabric, they present amorphous absolutely. For semi-IPN gel electrolyte, the mechanical and the electrochemical properties are varied with the quantity of absorbed liquid electrolyte. Ion-conductivity behavior for semi-IPN gel electrolyte measured by means of AC impedance spectrum showed that the best data was 1.62 × 10⁻³S cm⁻¹ at room temperature, and Arrhenius-type relationship was obeyed in the temperature dependence of ionic conductivity. In addition, the electrochemical stability window of the semi-IPN gel electrolyte was 4.6 V. All the properties showed that the prepared semi-IPN gel electrolyte was expected to have applications of electrolyte for lithium-ion polymer secondary batteries. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

凝胶聚合物电解质的电化学性能

用化学交联法制备了凝胶聚合物电解质.聚烯烃多孔膜支撑的凝胶聚合物电解质具有优良的电化学性能, 室温电导率为1.01×10^-3S•cm^-1,锂离子迁移数为0.41,在Al电极上的氧化起始电位达到4.2 V以上.采用聚烯烃多孔膜支撑的凝胶聚合物电解质制备了聚合物锂离子电池,并研究了工艺条件对聚合物锂离子电池电化学性能的影响.研究的工艺条件包括：单体添加量和电极组合方式.优化后的聚合物锂离子电池具有良好的电化学性能,1 C放电容量为0.2 C放电容量的93.2%,经100次1 C循环后的剩余容量仍在80%以上.     

A novel polymeric gel electrolyte systems containing magnesium salt with ionic liquid

A new polymeric gel electrolyte system consisting of poly(ethylene oxide)-modified polymethacrylate (PEO-PMA) with organic ionic liquid dissolving magnesium salt, Mg[(CF₃SO₂)₂N]₂, has been developed. The ionic conductance and electrochemical properties of the gel films were investigated. The obtained gel film was self-standing, transparent and flexible with sufficient mechanical strength. Thermal analysis of the gel film showed that it is homogeneous and amorphous over a wide temperature range. The highest conductivity, ca. 3.5 mS cm⁻¹ at 60 °C, was obtained for the polymeric gel containing 80 wt.% of the liquid component that consists of 80 mol% of EMITFSI (1-ethyl-3-methylimidazolium bis(trofluoromethylsulfonyl)imide) and 20 mol% of Mg[(CF₃SO₂)₂N]₂. The sort of the ionic liquid affected much on the ionic conductivity of the gel. The dc polarization of a Pt/polymeric gel electrolyte/Mg cell proved that the magnesium ion (Mg²⁺) can mobile in the present polymeric gel system.     

Fabrication and properties of crosslinked poly(propylene carbonate maleate) gel polymer electrolyte for lithium‐ion battery

The poly(propylene carbonate maleate) (PPCMA) was synthesized by the terpolymerization of carbon dioxide, propylene oxide, and maleic anhydride. The PPCMA polymer can be readily crosslinked using dicumyl peroxide (DCP) as crosslinking agent and then actived by absorbing liquid electrolyte to fabricate a novel PPCMA gel polymer electrolyte for lithium‐ion battery. The thermal performance, electrolyte uptake, swelling ratio, ionic conductivity, and lithium ion transference number of the crosslinked PPCMA were then investigated. The results show that the T_g and the thermal stability increase, but the absorbing and swelling rates decrease with increasing DCP amount. The ionic conductivity of the PPCMA gel polymer electrolyte firstly increases and then decreases with increasing DCP ratio. The ionic conductivity of the PPCMA gel polymer electrolyte with 1.2 wt % of DCP reaches the maximum value of 8.43 × 10⁻³ S cm⁻¹ at room temperature and 1.42 × 10⁻² S cm⁻¹ at 50°C. The lithium ion transference number of PPCMA gel polymer electrolyte is 0.42. The charge/discharge tests of the Li/PPCMA GPE/LiNi_1/3Co_1/3Mn_1/3O₂ cell were evaluated at a current rate of 0.1C and in voltage range of 2.8–4.2 V at room temperature. The results show that the initial discharge capacity of Li/PPCMA GPE/LiNi_1/3Co_1/3Mn_1/3 O₂ cell is 115.3 mAh g⁻¹. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Semi-interpenetrating gel polymer electrolyte based on PVDF-HFP for lithium ion batteries

Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based gel polymer electrolyte (GPE) is considered one of the promising candidate electrolytes in the polymer lithium ion battery (LIB) because of its free standing, shape versatility, security, flexibility, lightweight, reliability, and so on. However, the pristine PVDF-HFP GPE cannot still meet the requirement of large-scale LIBs and other electrochemical devices due to its relatively low ionic conductivity and deterioration of mechanical strength caused by the incorporation of organic liquid electrolyte into the polymer matrix as well as high cost. In order to overcome above deficiencies of PVDF-HFP based GPE, ultraviolet (UV)-curable semi-interpenetrating polymer network is designed and synthesized through UV-irradiation technique, and the as-prepared semi-interpenetrating matrix is constituted by pentaerythritol tetracrylate polymer network and PVDF-HFP. The ionic conductivity of the optimized GPE is as high as 5 × 10⁻⁴ S/cm and electrochemical window is up to 4.8 V at room temperature. Especially, the LIB prepared by GPE shows the high initial discharge specific capacity of 151 mAh/g at 0.5 C and good rate capability. Therefore, the semi-interpenetrating GPE based on PVDF-HFP exhibits a promising prospect for the application of rechargeable LIBs.     

Poly(methylmethacrylate)—magnesium triflate gel polymer electrolyte for solid state magnesium battery application

A gel polymer electrolyte (GPE) film of poly(methylmethacrylate) and magnesium triflate is studied in view of its potential application in a solid state rechargeable magnesium battery. Experimental data of a.c. impedance and cyclic voltammetric studies of symmetrical cells made of blocking and non-blocking electrodes, and also data of charge/discharge cycles of Mg/GPE/MnO₂ cells are reported. The composition of the GPE is optimized in view of a minimum quantity of the liquid components (propylene carbonate and ethylene carbonate) required for the gel formation and a maximum conductivity. Specific conductivity (σ) of the GPE of optimum composition is (4.2±0.45)×10⁻⁴ S cm⁻¹ at 20 °C. The σ values follow the Arrhenius equation and the activation energy for GPE of optimum composition is 0.038 eV. The effects of temperature and ageing on Mg/GPE interface are studied. Discharge capacity of about 90 mAh g⁻¹ of MnO₂ is obtained during the discharge of Mg/GPE/MnO₂ cells. On repeated charge/discharge cycling of the cell, the discharge capacity decreases to about 70 mAh g⁻¹. The cycle-life is limited by the problems associated with passivation of the Mg surface.     

Microporous poly(acrylonitrile-methyl methacrylate) membrane as a separator of rechargeable lithium battery

We studied microporous poly(acrylonitrile-methyl methacrylate), AMMA, membrane as the separator of Li/LiMn₂O₄ cell. The porous AMMA membrane was prepared by the phase inversion method with N,N-dimethylformamide (DMF) as the solvent and water as the non-solvent. We observed that morphology of the resulting membrane was strongly affected by the concentration of polymer solution: low concentration produced finger-like pores with dense skin on two surfaces of the membrane, while high concentration yielded open voids with dense layer on the other surface of the membrane. Regardless of their morphology, both membranes could be rapidly wetted by the liquid electrolyte (1.0 m LiBF₄ dissolved in 1:3 wt.% mixture of ethylene carbonate (EC) and γ-butyrolactone (GBL)), and could be swollen at elevated temperatures, which resulted in the formation of a microporous gel electrolyte (MGE). It was shown that the resulting MGE not only had high ionic conductivity and but also had good compatibility with metal lithium even at 60 °C. Cyclic voltammetric test showed that the MGE had an electrochemical window of 4.9 V versus Li⁺/Li. At room temperature, the Li/MGE/LiMn₂O₄ cell showed excellent cycliability with a specific capacity of 121-125 mA h g⁻¹ LiMn₂O₄. It was shown that even at 60 °C good mechanical strength of the MGE remained. Therefore, the MGE is suitable for the application of battery separator at elevated temperatures.     

Microporous polyurethane/acrylate gel polymer electrolyte obtained by emulsion polymerization

A novel polyurethane/acrylate (PUA) porous gel electrolyte was prepared by a new method, emulsion polymerization. Compared with the traditional phase inversion method, the new method can eliminate the pollution from solvent and decrease the cost of production. The swelling properties and morphology of the porous polymer membranes were characterized. The porous membranes, made by emulsion polymerization, could absorb large quantities of electrolyte solution to form porous gel electrolytes. The gel electrolytes have good solvent retention ability and high ionic conductivity. Copyright © 2004 Society of Chemical Industry     

Effect of KOH concentration in the gel polymer electrolyte for direct borohydride fuel cell

The performance of a direct borohydride fuel cell (DBFC) based on a polyacrylamide (PAAm) gel polymer electrolyte system is investigated at different electrolyte concentrations. The DBFC, constructed using 2M sodium borohydride (NaBH₄) as the fuel and potassium hydroxide (KOH) solution gelled with PAAm as the electrolytes yield the highest electrical conductivity of 2.73 × 10^?1 S cm^?1 at 6M KOH. The optimized composition, PAAm + 2M NaBH₄ + 6M KOH, and the selected composition, PAAm + 2M NaBH₄ + 3M KOH are then used in preparing the cells. Open‐circuit voltages for fuel cells is about 0.85–0.92 V, and the discharge characteristic produce discharge capacities of about 257.12–273.12 mAh cm^?2 for cells with PAAm‐6M KOH. Current‐voltage and current density‐power density plots and internal resistance for both cells are almost the same. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

增塑型锂离子电池聚合物电解质

从组成聚合物电解质的聚合物基材和电解液两方面进行分析,介绍了最近几年凝胶型、微孔型和复合型聚合物电解质的研究现状,比较了它们的制备方法、性能和特点,探讨了锂盐、增塑剂、离子液体和单离子导体等对聚合物电解质性能的影响,并简要评述了聚合物锂离子电池未来发展的前景趋势。     

Ionic conductivity of new dual-phase polymer electrolyte composed of poly(epichlorohydrin-co-oxirane) and NBR

A new type of dual-phase polymer electrolyte (DPE) film was prepared by mechanical mixing of a poly(epichlorohydrin-co-oxirane) (ECO) and poly(acrylonitrile-co-butadiene) rubber (NBR) binary solution and then by solution casting. Both of the polymers are commercially available. The casting films were swollen with a LiClO₄/propylene carbonate (PC) solution to obtain DPE films. The ionic conductivity of the DPE films was calculated on the basis of alternating current impedance measurements. The results showed that the ionic conductivity is dependent on the content of the LiClO₄/PC solution and the ECO/NBR blend ratio. High ionic conductivity (>10⁻³ S/cm at 298 K) was achieved when the ECO content in the matrix is 90% (w/w), the contentration of LiClO₄/PC solution is at 3 mol/L, and the weight percent of LiClO₄/PC is 40. The impedance spectrum provided evidence that a dual-phase structure was created, in which the ECO phase provided an ion-conductive pathway and the NBR phase acted as a supportive matrix. A new ionic conductivity mechanism was proposed. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 353–357, 1998     

用于锂离子电池的改性凝胶聚合物电解质

综述了凝胶聚合物电解质的性能影响因素和改性方法;着重介绍了无机纳米粒子掺杂改性;论述了近年来离子液体在聚合物电解质方面的应用;展望了凝胶聚合物电解质的发展及应用前景。     

A novel PEO-based composite polymer electrolyte with absorptive glass mat for Li-ion batteries

A novel PEO (polyethylene oxide)-based composite polymer electrolyte (CPE) using absorptive glass mat (AGM) as filler was prepared and characterized. Scanning electronic micrograph (SEM) images showed that the addition of Li salt and modified AGM may improve the surface morphology of CPE. The results of Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and differential scanning calorimeters (DSC) indicated that the inclusion of LiClO₄ salt and the addition of AGM filler can reduce the crystallinity of PEO. It was concluded that the addition of AGM plays two roles in PEO-based CPEs, namely, interruption of the PEO recrystallization and reinforcement of CPEs, accordingly enhancing room temperature ionic conductivity of CPEs and improving its mechanical strength and electrochemical stability at high temperatures.     

Lithium polymer batteries using the highly porous membrane filled with solvent-free polymer electrolyte

Solid polymer electrolyte supported by a microporous membrane was prepared and characterized. The polymer electrolyte was prepared by penetrating the highly conductive solvent-free polymer electrolyte based on poly(oligo [oxyethylene] oxyterephthaloyl) into the pores of the highly porous membrane. The electrochemical characteristics of the solid polymer electrolytes are presented, and we discuss the possibility of them as an electrolyte material for lithium polymer batteries.