Microporous Polymer Electrolyte Research Articles

Novel PVA/SiO2Alkaline Micro-porous Polymer Electrolytes for Polymer Ni—MH Batteries

New poly(vinyl alcohol)/silica (designated as PVA/SiO2) alkaline micro-porous polymer electrolytes (AMPEs) were prepared by soaking PVA/SiO2 micro-porous composite membranes, obtained by solution casting of PVA/PEG/SiO2 membrane in acetone solution, into an electrolyte solution of 6 mol/L KOH aqueous solution. The morphology and structure of PVA/SiO2 composite polymer membranes were characterized by scanning electron microscopy (SEM) and X-Ray diffrac- tion (XRD). The SEM photographs showed that the nano-SiO2 filler content was a crucial issue for the well-dispersed and optimal-sized pores which could storage charge carrier durably. Meanwhile, the crystalline of PVA decreased effectively for a large number of crystal defects and free volume appeared in the interface of inorganic particles and polymer for the addition of nano-SiO2 filler. The electrochemical properties of the AMPEs were measured by the alternating current impedance (AC impedance) and the cyclic voltammetry (CV) techniques. The results indicated that the PVA/SiO2 AMPEs containing 5 ω nano-SiO2 filler exhibited good performances at room temperature, such as 1.62×10 -2 Scm -1 for ionic conductivity and 2.20 V for electrochemical stability window. What's more, we used the gravimetric method to obtain the electrolyte uptake of various PVA/SiO2 composite micro-porous polymer membranes. From the data, we learned that the maximum electrolyte uptake could reach to 102.7% and it had very relevance to the size of pores in PVA/SiO2 composite polymer membranes, and then influenced the ionic conductivity. Each polymer Ni-MH battery was assembled by three parts: the new AMPE, Mg-based hydrogen storage alloy and the commercial sintered Ni(OH)2/NiOOH electrode, in which each part did for electro- lyte and diaphragm, negative electrode and positive electrode, respectively. The cycle experiments of the batteries exhibited a high first-cycle discharge capacity of 613 mAhg -1 and stable discharge capacities about 330 mAhg -1 for the following 5 cycles. The results encouraged that the novel AMPEs are prospective for the applications of polymer electrolyte in Ni-MH battery field. Keywords PVA; alkaline micro-porous polymer electrolyte; ionic conductivity; cycling stability; polymer Ni-MH battery

Ionic Conductivity of PVC Based Microporous Polymer Membrane Electrolyte

A microporous polymer membrane based on polyvinyl chloride (PVC) was obtained by a novel polymer dissolution technique in different compositions of (PVC-PVA). The structural study of the prepared PVC microporous membrane was carried out by x-ray diffraction. TGA/DTA analysis reveals that the microporous polymer membrane is thermally stable up to 600 0 C. Ionic conductivity of polymer membrane electrolytes have been determined by impedance studies in the temperature of 303- 343 K by varying the PVA content in PVC matrix. The ionic conductivity at room temperature was significantly enhanced about 5.431x10 -4 S/cm when the weight ratio of PVA was 40 wt%. Finally the effect of different lithium salt concentration was also studied for the microporous polymer electrolyte of high ionic conductivity system. A maximum ionic conductivity of 1.29x10 -3 S/cm was obtained for 3 M LiClO4 electrolyte solution at ambient temperature.

Morphology and Electrochemical Properties of P(VdF-HFP)/MgO-Based Composite Microporous Polymer Electrolytes for Li-Ion Polymer Batteries

A hybrid, poly(vinylidenefluoride-co-hexafluoropropylene) P(VdF-HFP)/MgO-based pristine composite polymer electrolyte (PCPE) and composite microporous polymer electrolyte (CMPE) have been prepared successfully by polymer dissolution method. Different morphology of the composite membrane was examined by field emission scanning electron microscopy. The conductivity of the PVP extracted CMPE is higher than that of optimized filler (8 wt% MgO) incorporated PCPE. It proved good compatibility with lithium electrodes, and an electrochemical stability window spanning the range of 0.0 to 5.0 V vs. Li/Li+. The performance of CMPE is relatively high and stable when compared with PCPE for rechargeable lithium-ion polymer batteries.

Preparation and application of TEMPO-based di-radical organic electrode with ionic liquid-based polymer electrolyte

In this study we report the synthesis and use of new organic materials, TEMPO di-radical [1,3-bis(4-(2,2,6,6,-tetramethyl-1-oxyl-4-piperidoxyl)butyl) imidazolium trifluorosulfonate]. Two cells were prepared with Li metal anode and the TEMPO di-radical based cathode with a microporous polymer electrolyte [1-butyl-3-methyl imidazolium bis(trifluoromethane sulfonyl) imide (BMImTFSI) in 0.5 M LiTFSI, and in 1 M LiPF6 in ethylene carbonate/dimethyl carbonate (EC/DMC)] hosted in electrospun poly(vinylidenefluoride-co-hexafluoropropylene) (PVdF-HFP) membrane. The nature of the solvent was not found to affect the basic redox reaction behavior of TEMPO. The anodic and cathodic peaks were obtained at almost the same position and with some difference in the separation of peaks. The presence of BMImTFSI significantly affects the electrochemical performance of the battery as the cell having this RTIL exhibited far better electrochemical performance with 100% utilization of the active material and reasonably good cycling performance up to 200 cycles. We believe that this composite cell will contribute to organic green rechargeable batteries, although the cell is not fully organic composite.

Microporous gel polymer electrolytes for lithium rechargeable battery application

Microporous poly(vinylidene fluoride)/poly(methyl methacrylate) (PVDF/PMMA) membranes were prepared using the phase-separation method. Then, the membranes were immersed in liquid electrolyte to form polymer electrolytes. The effects of PMMA on the morphology, degree of crystallinity, porosity, and electrolyte uptake of the PVDF membrane were studied. The addition of PMMA increased the pore size, porosity and electrolyte uptake of the PVDF membrane, which in turn increased the ionic conductivity of the polymer electrolyte. The maximum ionic conductivity at room temperature was 1.21 × 10 −3 S cm −1 for Sample E70. The polymer electrolyte was investigated, along with lithium iron phosphate (LiFePO 4) as cathode for all solid-state lithium-ion rechargeable batteries. The lithium metal/E70/LiFePO 4 cell yielded a stable discharge capacity of 133 mAh g −1 after up to 50 cycles at a current density of 8.5 mA g −1.

Organic acid doped polythiophene nanoparticles as electrode material for redox supercapacitors

AbstractAn organic acid doped electronically conducting polymer nanomaterial, polythiophene‐tartaric acid (PTh‐TA) nanoparticles, was prepared by cationic surfactant‐assisted dilute polymerization method. The physical properties of the synthesized polymer were characterized by FT‐IR, UV‐visible spectroscopy, X‐ray diffraction, SEM, and electrical conductivity studies. The symmetric type redox supercapacitor performances were studied in PVdF‐HFP in 1 M LiPF6 containing EC&PC (1:1 v/v) based microporous polymer electrolyte. The specific capacitance of the capacitor was found to be 156 F g−1. The energy and power densities were calculated as 14 Wh kg−1 and 522 W kg−1, respectively. The value of capacitance was found to be almost stable up to 1000 cycles and even more. Copyright © 2009 John Wiley & Sons, Ltd.

Preparation and characterization of a microporous polymer electrolyte based on poly(vinylidene fluoride)/ionic‐liquid‐functionalized SiO2 for dye‐sensitized solar cells

AbstractA new type of ionic‐liquid‐functionalized SiO2 (IL‐SiO2) was synthesized to develop a microporous polymer electrolyte for quasi‐solid‐state dye‐sensitized solar cells. The samples were characterized by 1H‐NMR, Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, and X‐ray diffraction. Moreover, the ionic conductivity of the electrolytes was measured by an electrochemical workstation. Nanostructured silica containing imidazolium iodide showed excellent compatibility with the organic solvent. The incorporation of the IL‐SiO2 component into the polymer matrix improved the electrochemical behavior of the gel polymer electrolyte. A dye‐sensitized solar cell with a gel polymer electrolyte yielded an open‐circuit voltage of 0.662 V, a short‐circuit current of 13.40 mA/cm2, and a conversion efficiency of 4.01% at 1 sun illumination. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

New Microporous Polymer Electrolyte Based on Polysiloxane Grafted with Imidazolium Iodide Moieties for DSSC

Two types of polysiloxane grafted with different ratio of imidazolium iodide moieties (IL-) have been synthesized to develop a micro-porous polymer electrolyte for quasi-solid-state dye-sensitized solar cells. The samples were characterized by , FT-IR spectrum, XRD, TEM and SEM, respectively. Moreover, the ionic conductivity of the electrolytes was measured by electrochemical workstation. Nanostructured polysiloxane containing imidazolium iodide showed excellent compatibility with organic solvent and polymer matrix for its ionic liquid characteristics. Increasing the proportion of imidazolium iodide moieties in polysiloxane improved the electrochemical behavior of the gel polymer electrolyte. A dye-sensitized solar cell with gel polymer electrolyte yielded an open-circuit voltage of 0.70 V, short-circuit current of 11.19 mA , and the conversion efficiency of 3.61% at 1 sun illumination.

A novel poly(vinylidene fluoride-hexafluoropropylene)/poly(ethylene terephthalate) composite nonwoven separator with phase inversion-controlled microporous structure for a lithium-ion battery

We demonstrate a novel and facile approach to fabrication of a new composite nonwoven separator for a lithium-ion battery, which comprises a phase inversion-controlled, microporous polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP) gel polymer electrolyte and a polyethylene terephthalate (PET) nonwoven support. The thermally stable PET nonwoven is chosen as a mechanical support and contributes to improving the thermal shrinkage of the composite nonwoven separator. The microporous PVdF-HFP gel polymer electrolyte serves as a pore size controller for the composite nonwoven separator. In order to provide a theoretical basis for this approach, an investigation of the phase diagram for coating solutions consisting of PVdF-HFP, solvent (acetone), and nonsolvent (water) is preceded. Based on this understanding of the phase behavior, the effects of phase inversion, more specifically, the water content in the coating solutions, on the morphology evolution of the composite nonwoven separators are identified. The phase inversion-governed microporous structures of the composite nonwoven separators play a crucial role in determining electrochemical performances of cells. The composite nonwoven separator is expected to be a promising alternative to a commercialized polyethylene (PE) separator, particularly in next-generation lithium-ion batteries necessitating superior battery safety and performance.

Ionic transport in P(VdF-HFP)-PEO based novel microporous polymer electrolytes

A novel microporous polymer electrolyte (MPE) comprising blends of poly(vinylidene fluoride-cohexafluoropropylene) [P(VdF-HFP)] and polyethylene oxide (PEO) was prepared by phase inversion technique. It was observed that addition of PEO improved the pore configuration, such as pore size, pore connectivity and porosity of P(VdF-HFP) based membranes. The room temperature ionic conductivity was significantly enhanced. The highest porosity of about 65% and ionic conductivity of about 7 × 10−4 S cm−1 was obtained when the weight ratio of PEO was 40%. The liquid electrolyte uptake was found to increase with increase in porosity and pore size. However, at higher weight ratio of PEO (> 40%) porosity, pore size and ionic conductivity was decreased. This descending trend with further increase of PEO weight ratio was attributed to conglomeration effect of PEO at the pores.

Composite Micro-porous Polymer Electrolyte of PVDF-HFP Modified by MCM-48

Composite Micro-porous Polymer Electrolyte of PVDF-HFP Modified by MCM-48

Imidazolium‐organic solvent–alkali metal salt mixtures as nonflammable electrolytes incorporated into PVDF–PEG polymer electrolyte

AbstractA mixture of flammable organic solvent, alkali metal salt, and nonflammable room temperature ionic liquid has been used as a new type of electrolyte. A novel microporous polymer electrolyte based on poly(vinylidene fluoride), i.e., PVDF, and poly(ethylene glycol), i.e., PEG, was prepared by a simple phase‐inversion technique. The mixed electrolyte was observed to be nonflammable at ionic liquid contents of 60 vol % or greater. The viscosity (range, 0.98–30.5 mPa s) and conductivity (range, 9.9 to 22.25 mS cm−1) of the mixed electrolyte were discussed. The porosity, solution uptake, and conductivity mechanism of polymer membranes also were discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

NOVEL POLYMER ELECTROLYTE BASED ON POLY(VINYLIDENE FLUORIDE) AND POLY(4-VINYL PYRIDINE) HAVING A NANO-CHANNEL FOR ION TRANSPORTATION

The micro-porous polymer electrolytes membranes(PEMs), notably electro-spun fiber mats, have been suggested to give an improved ionic conductivity. However, the mat-type PEMs have a poor mechanical and dimensional stability because of their inevitable porous nature. In this study, we suggest a new PEM system based on poly(vinylidene fluoride)(PVdF) mats, which can overwhelm such shortcomings of the porous mats by introducing another component, poly(4-vinyl pyridine)(P4VP), into the mats. The tensile strength of PVdF / P 4 VP membrane was considerably improved compared with that of pristine PVdF membrane under dry and wet conditions. The ionic conductivity was also improved by about 10 times than that of PVdF mat. A micro- to nano-size gap was formed at the interfaces between PVdF nanofiber and P 4 VP , and this may act as a channel for fast ion transportation under wet condition.

Effect of Active Filler Addition on the Ionic Conductivity of PVDF-PEG Polymer Electrolyte

A novel composite microporous polymer electrolyte based on poly(vinylidene fluoride), PVDF, poly(ethylene glycol), PEG, and Li-exchanged vermiculite(Li-VMT)was prepared by a simple phase inversion technique. The prepared membrane was subjected to XRD, SEM, impedance spectroscopy. The incorporation of Li-exchanged vermiculite greatly enhanced the ionic conductivity and solvent uptake as compared to the membrane without Li-exchanged vermiculite. The Li-exchanged vermiculite plays a active role in ion transport since relatively large platelets serve as the anion and allowed for exceptionally large Li transference numbers.

Polyethylene-supported poly(acrylonitrile-co-methyl methacrylate)/nano-Al2O3 microporous composite polymer electrolyte for lithium ion battery

Nano-Al2O3 was doped in poly(acrylonitrile-co-methyl methacrylate) (P(AN-co-MMA)), and polyethylene(PE)-supported P(AN-co-MMA)/nano-Al2O3 microporous composite polymer electrolyte (MCPE) was prepared. The performances of the prepared MCPE for lithium ion battery use, including ionic conductivity, electrochemical stability, interfacial compatibility, and cyclic stability, were studied by scanning electron spectroscopy, linear sweep voltammetry, and electrochemical impedance spectroscopy. It is found that the nano-Al2O3 significantly affects the MCPE performances. Compared to the MCPE without any nano-Al2O3, the MCPE with 10 wt.% nano-Al2O3 reaches its best performances. Its ionic conductivity is improved from 2.0 × 10−3 to 3.2 × 10−3 S cm−1, its decomposition potential is enhanced from 5.5 to 5.7 V (vs Li/Li+), and its interfacial resistance on lithium is reduced from 520 to 160 Ω cm2. Thus, the battery performance is improved.

Effect of functionalized montmorillonite addition on the thermal properties and ionic conductivity of PVDF–PEG polymer electrolyte

Composite microporous polymer electrolyte membranes comprising poly(vinylidene fluoride), PVDF, poly(ethylene glycol), PEG, and 1-ethyl-3-methylimidazolium tetrafluoroborate functionalized montmorillonite (EMIm-MMT) were prepared by a phase inversion method. The EMIm-MMT was subjected to FTIR, WXRD, TGA and element analysis in order to better understand the intercalation of imidazolium cations in sodium montmorillonite (Na-MMT) through exchange with intermellar sodium ions and improved thermal stability compared to organic-montmorillonite (O-MMT). The studies of porosity, weight uptake, and ionic conductivity of composite microporous membrane were performed as a function of EMIm-MMT content. The addition of EMIm-MMT can greatly enhance the thermal stability of the polymer electrolyte membrane. The maximum conductivity at 25 °C was found to be 7.77 mS cm −1 for PVDF–PEG/6wt% EMIm-MMT.

Phase inversion process to prepare quasi-solid-state electrolyte for the dye-sensitized solar cells

A quasi-solid-state electrolyte for the dye-sensitized solar cells was prepared following the phase inversion process. The microporous polymer electrolyte based on poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) hybrid with different amount of TiO2 nanoparticles were prepared. The surface morphologies, the differential scanning calorimetry, and the ionic conductivity of the microporous polymer electrolyte were tested and analyzed. The results indicated that the microporous polymer electrolyte with TiO2 nanoparticles modification exhibited better ionic conductivity compared with the original P(VDF-HFP) polymer electrolyte. The optimal ionic conductivity of 0.8 mS cm−1 is obtained with the 30 wt % TiO2 nanoparticles modification. When assembled with the 30 wt % TiO2 nanoparticles modified quasi-solid-state electrolyte, the dye-sensitized TiO2 nanocrystalline solar cell exhibited the light to electricity conversion efficiency of 2.465% at light intensity of 42.6 mW cm−2, much better than the performance of original P(VDF-HFP) microporous polymer electrolyte DSSC. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

P(VDF-HFP)-based micro-porous composite polymer electrolyte prepared by in situ hydrolysis of titanium tetrabutoxide

A micro-porous composite polymer electrolyte (MCPE) was prepared in situ by adding TiO2 nanoparticles from the hydrolysis of titanium tetrabutoxide to a solution of poly(vinylidenefluoride-co-hexafluoropropylene) [P(VDF-HFP)] copolymer. The prepared microporous polymer films (MCPFs) were characterized by scanning electronic microscopy, X-ray diffraction, thermogravimetric analysis, FT-IR and electrochemical interface resistance. After the addition of TiO2 nanoparticles the polarity of CF2 groups in the polymer chains and the crystallinity of the MCPFs decreased. When the composite polymer film contained 8.5 wt% of TiO2 nanoparticles the MCPE exhibited excellent electrochemical properties such as high ionic conductivity, up to 2.40 × 10−3 S cm−1 at room temperature.

Preparation and electrochemical characterization of electrospun, microporous membrane-based composite polymer electrolytes for lithium batteries

Poly(vinylidene fluoride-co-hexafluoropropylene) {P(VdF-HFP)} membranes incorporating 0, 6 and 10 wt.% of nano-meter sized particles of SiO 2 were prepared by electrospinning. These membranes served as host matrix for the preparation of polymer electrolytes (PEs) by activating with the non-volatile and safe room temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonylimide) (BMITFSI). The membranes consisted of layers of fibers with average fiber diameter of 2–5 μm and had a porosity of ∼87%. PEs with SiO 2 exhibited higher ionic conductivity with a maximum of 4.3 × 10 −3 S cm −1 at 25 °C obtained with 6% SiO 2. The optimum PE based on the membrane with 6% SiO 2 exhibited better compatibility with lithium metal electrode on storage and resulted in enhanced charge–discharge performance in Li/LiFePO 4 cells at room temperature, delivering the theoretical specific capacity of 170 mAh g −1 at 0.1 C-rate. The PEs exhibited a very stable cycle property as well, demonstrating their suitability for lithium battery applications.

Preparation and characterization of a micro-porous polymer electrolyte with cross-linking network structure for dye-sensitized solar cell

A PVdF-HFP/PEG/PEGDMA cross-linking film has been prepared as the electrolyte for dye-sensitized solar cell (DSSC). The film can be made porous by controlling the evaporation behavior of solvents. Room temperature ionic conductivity of the micro-porous film exceeds 1 mS/cm. In addition, we also evaluated the significance of cell gap in DSSC by analyzing the impedance spectroscopy of the cell with polymer electrolyte. Finally, by decreasing the film thickness, the DSSC equipped with 11 μm, micro-porous and cross-linked film showed a conversion efficiency over 4% and 5% under 1 and 0.16 Sun, respectively.