Polymer Electrolyte Matrix Research Articles

Synthesis and characterization of a new network polymer electrolyte containing polyether in the main chains and side chains

A new network polymer electrolyte matrix with polyether in the side chains and main chains was synthesized by the azo-macroinitiator method and urethane reaction. The macroinitiator, polymer and network polymer were confirmed by Fourier-transform infrared (FT-IR) spectroscopy and 1H NMR. FT-IR was also used to study the environment of lithium ions doped in these network polymer electrolytes. Three important groups are considered: N–H, carbonyl, and ether groups. The thermal properties of the polymer electrolytes were measured by differential scanning calorimetry and thermogravimetric analysis. The T g value of this polymer is less than that of a general comb-like polymer. Added lithium ions interact with the oxygen atoms on ether groups, causing the T g of the polymer electrolyte to increase. Moreover, the interaction between lithium ions and ether groups decreases the decomposition temperature of the polymer. The conductivity measured by AC impedance reached a maximum of 10 −4 S cm −1. A plot of conductivity vs. temperature fit the Vogel–Tamman–Fulcher equation, indicating that ionic mobility in this network polymer electrolyte is coupled to segmental chain movements.

Influence of silica aerogel on the properties of polyethylene oxide-based nanocomposite polymer electrolytes for lithium battery

In this study, a series of nanocomposite polymer electrolytes (NCPEs) with high conductivity and lithium ion transference number, PEO/LiClO 4/SAP, were prepared from high molecular weight polyethylene oxide (PEO), LiClO 4 and low content of homemade silica aerogel powder (SAP), which had higher surface area and pore volume than the conventional silica particle. From the SEM images it was found that the SAP nanoparticles were well dispersed in the PEO polymer electrolyte matrix. The characterization and interactions in the CPEs were studied by DSC, XRD, FT-IR and 7Li NMR analysis. The ac impedance results showed that the ionic conductivity of the CPE was significantly improved by the addition of the as-prepared SAP. The maximum ambient ionic conductivity obtained from the CPE with EO/Li = 6 and 2 wt.% of SAP (O6A2) was about threefold higher than that of the corresponding polymer electrolyte without SAP (O6). In addition, the lithium ion transference number ( t +) of O6A2 at 70 °C was as high as 0.67, which was also three times higher than that of O6 and has not been previously reported for the PEO–LiX-based polymer electrolytes.

Enhancement of piezoelectric and pyroelectric properties of composite films using polymer electrolyte matrix

Composite films consisting of lead zirconate titanate (PZT) inclusions dispersed in a matrix of polymer electrolyte the polyethylene oxide were fabricated. Their piezoelectric coefficients d33 and pyroelectric coefficients p are increased almost proportional to the volume fraction of the ferroelectric ceramic phase. For 34% PZT composite, d33 and p are 170pC∕N and 120μC∕m2K, respectively, they are much larger than PZT/polyvinylidene fluoride-trifluoroethylene composite with similar ceramics content. It is believed that the enhancement of the measured coefficients is due to the relatively high electrical conductivity of polymer electrolyte matrix. This is confirmed by theoretical models which consider the conductivity of matrix.

Effects of processing conditions on the electrical switching performance of nanoparticulate PEDOT composites showing large field-controlled impedance change

Composite materials containing nanoparticulate PEDOT in a polymer electrolyte matrix containing either a Cu–Cu 2+ or Fe 2+–Fe 3+ redox couples show rapid and reversible decreases of up to 500-fold in their electrical and microwave impedances when small DC or AC electric fields are applied across coaxial line and strip samples from their edges, which are much larger than microparticulate PEDOT composites and make signification progress in this field. The composites show large field-dependent resistances at low applied fields and good electrochemical stability.

PVDF porous matrix with controlled microstructure prepared by TIPS process as polymer electrolyte for lithium ion battery

Poly(vinylidene fluoride) (PVDF) microporous matrix of polymer electrolyte for lithium ion battery was prepared via the thermally induced phase separation (TIPS) process using diluent mixture of dibutyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP). Since this method has only one parameter, namely the DBP/DEHP ratio in diluent mixture, the membrane microstructure is easily and conveniently controlled. With the assistance of a pseudo-binary temperature-DBP ratio phase diagram of the PVDF-diluent mixture system, the membrane formation mechanism for different microstructures of membranes was proposed. In addition to studying the different microstructures available in TIPS process, the relationship between performance of membrane, electrochemical property of polymer electrolyte and final microstructure has been investigated in this paper.

Conductivities of electrolytes based on PEI- b-PEO- b-PEI triblock copolymers with lithium and copper TFSI salts

Tri block-copolymer poly(iminoethylene)- b-poly(oxyethylene)- b-poly(iminoethylene) with a poly(oxyethylene) central block (PEI- b-PEO -b-PEI) were used as a “dual” matrix for polymer electrolytes having selectivity for hard cations (Li +/PEO) in one phase and for soft cations (Cu 2+/PEI) in the other. Conductivity measurements were recorded for 20:1, 12:1 and 8:1 coordinating atom (O or/and N) to cation (Li +, Cu 2+) ratios, for each of the three complexes studied: PEI- b-PEO-LiTFSI- b-PEI, PEI-Cu(TFSI) 2- b-PEO- b-PEI-Cu(TFSI) 2 and PEI-Cu(TFSI) 2- b-PEO-LiTFSI- b-PEI-Cu(TFSI) 2. For either low (20 °C) or high temperature (80 °C) the highest conductivity was given by the polymer electrolyte based on Cu(TFSI) 2 with N/Cu 2+ = 20:1 (10 − 6 , respectively 2 × 10 − 4 S cm − 1 ). In the present paper, the conductivity evolution is discussed in relation with the polymer structure, the type and the concentration of the salt and the thermal behavior of our systems.

Synthesis and characterization of new block copolymer electrolytes with solvating affinities for different cations

Poly(iminoethylene)- b-poly(oxyethylene)- b-poly(iminoethylene) (PEI- b-PEO- b-PEI) polymers were synthesized and used as a “dual” matrix for polymer electrolytes having selectivity for “hard” cations (Li +/PEO) in one phase and for “soft” cations (Cu ++/PEI) in the other. Both blocks are phase-separated, but each segment tends to crystallize, influenced by water and salt. The synthesis and characterisation, including AFM imaging before and after the perfluorosulfonimide salts loading is being addressed. The new block copolymer electrolytes with solvating affinities for different cations could be used either as a reference electrode or in the fabrication of electrochromic devices.

Characterization and Properties of P(VdF-HFP)-Based Fibrous Polymer Electrolyte Membrane Prepared by Electrospinning

Microporous fibrous membranes were prepared from poly(vinylidenefluoride-co-hexafluoropropylene) P(VdF-HFP) solutions in an acetone/N,N-dimethylacetamide mixture using the electrospinning method. Varying the P(VdF-HFP) polymer concentration in electrospinning can easily control the pore size and the porosity of the electrospun fibrous membranes (ES-FMs). The usefulness of the ES-FMs as a matrix of polymer electrolyte for a lithium-ion polymer battery with high performance was evaluated. Electrospun fibrous polymer electrolyte membranes (ES-FPEMs) showed excellent electrochemical properties of ionic conductivity, higher than S/cm at room temperature, and the electrochemical stability window, up to 4.5 V vs. At a C/2 rate, the prototype cell using the ES-FPEM showed a good charge/discharge property, with little capacity fade under constant current and constant voltage conditions at 20 and 60°C. © 2004 The Electrochemical Society. All rights reserved.

Mixed phase solid polymer electrolytes based on poly(methylmethacrylate) systems

A composite polymer electrolyte PMMA–Li 2SO 4–DBP–ZrO 2 was prepared by a solution casting technique; poly(methymethacrylate) (PMMA), dibuthylphalate (DBP). A conductivity of 0.13×10 −6 S cm −1 can be achieved at room temperature for the composition PMMA–Li 2SO 4–DBP (25–5–70 mol%), whereas it improves an order of magnitude (7.5×10 −6 S cm −1) upon dispersing fine particles of ZrO 2 (particle size = 21.5 μm) as inert fillers into the above plasticized polymer electrolyte matrix. The role of the ceramic phase is to reduce the melting temperature and to retard the kinetics of crystallization of PMMA. This results in a conductivity relaxation below the melting temperature of PMMA, which appears to be a characteristic of these composite electrolytes.

A new microwave ‘smart window’ based on a poly(3,4-ethylenedioxythiophene) composite

The preparation and dc and microwave characterisation of a new microparticulate mixed polymeric conductor containing poly(3,4-ethylenedioxythiophene) (PEDOT) and copper metal in a poly(ethylene oxide)–Cu(BF4)2–LiBF4 polymer electrolyte matrix is described. The composites exhibit large, rapid and reversible changes in their microwave transmission coefficients when small dc or ac fields (5–7 V) are applied radially across annular samples (13 mm o.d.) from the edges. At 1 GHz, changes of −6 dB (0 V) to −15 dB (5 V) with switching speeds of ≤250 ms were observed, and −2 to −12 dB at slower rates. Single cell experiments show that redox processes are confined to thin surface layers of the PEDOT particles. A mechanism for switching involving the polarisation of PEDOT particles under an applied field is proposed.

리튬 유황전지용 폴리우레탄 고분자 전해질의 전기화학적 특성

Polyurethane was used as matrix for polymer electrolytes with liquid electrolyte consist of organic solvent as ethylene carbonate(EC), propylene carbonate(PC), and tetraethylene glycol dimethylether(TG) and 1M , which has high mechanical strength and porosity. Electrochemical properties fur polyurethane electrolytes with various liquid electrolytes were evaluated. The amount of immersed liquid electrolyte for TG with 1M was increased to about by weight, and initial discharge capacity and cycle performance was better than others. Ionic conductivity for TG/EC(v/v,1:1) and PC/EC(v/v, 1:1) with 1M was about

Effects of alumina whisker in (PEO) 8–LiClO 4-based composite polymer electrolytes

This paper reports the morphological, electrical and mechanical characteristics of the PEO-based composite polymer electrolytes with alumina whisker as fillers. The SEM results showed that serious microcracks occurred in the pristine PEO–LiClO 4 polymer electrolytes when they were quenched at room temperature and spherulites were allowed to form in the electrolytes. Addition of alumina whisker effectively prevented the formation of the microcracks. The whiskers were homogeneously dispersed in the polymer electrolyte matrix and exhibited excellent interconnection with PEO–LiClO 4 polymer electrolyte. The addition of whisker additives improved the ionic conductivity of the PEO–LiClO 4 polymer electrolytes to some extent when the content of the whisker was less than 20 wt.%. Moreover, the whisker could remarkably improve the mechanical performance of the PEO–LiClO 4 polymer electrolyte especially at the temperatures higher than its melting point.

Polypyrrole/Polymer Electrolyte Composites Prepared by In Situ Electropolymerization of Pyrrole as Cathode/Electrolyte Material for Facile Electron Transfer at the Solid Interface

Polypyrrole (PPy)/ion-conducting polymer electrolyte (PE) composites are prepared by in situ electropolymerization of pyrrole in a solvent-free PE matrix which is formed by photocross-linking of triacrylated poly(ethylene oxide-co-propylene oxide) (TA). X-ray photoelectron spectroscopy measurements reveal the gradient structure at the PPy/PE interface where PPy is formed with the concentration gradient. For the composite film, a facile electron transfer across the PPy/PE interface is demonstrated by a cyclic voltammogram for the doping-undoping process, and a decrease in the charge-transfer resistance at the interface is proved by an electrochemical impedance analysis. This is in marked contrast to a combined bilayer film of PPy and TA-based PE for which an electron transfer across the interface between two polymer films is not clearly observed. The composite exhibits charge-discharge performance, which suggests a possibility of fabricating solid-state batteries composed of conductive polymer electrode/ion-conductive PE/Li by one-step electrolysis. © 2001 The Electrochemical Society. All rights reserved.

Measurements of the Thermal Conductivity of Lithium Polymer Battery Composite Cathodes

The thermal conductivity of the composite cathode, which consists of polymer electrolyte and active material, is an important parameter for the thermal management and heat transport studies of lithium polymer batteries. Thermal conductivities of and composite cathode were measured by a guarded heat flowmeter over the lithium polymer batteries operating temperature range from 25 to 150°C. They were found to increase with the temperature up to the melting temperature of the polymer electrolyte, but to increase only slightly after the melting temperature. A heat transport mechanism of phonon transmission in the polymer electrolyte matrix and transport of lithium ions in the active materials can be used to explain the results. The effective thermal conductivity of the composite cathode can be estimated from the conductivities of polymer electrolyte and active materials. To determine the latter, measurements were also made of the thermal conductivities of pressed samples of and . The measurements of composite cathodes, along with measurements of lithium polymer electrolytes, previously published by this journal, complete the work on the thermal conductivities of lithium polymer battery cell components, which can be used to estimate the thermal conductivities of the cell using thermal‐resistance‐in‐series/parallel models. © 1999 The Electrochemical Society. All rights reserved.

Lithium-ion conducting ceramic/polyether composites

Composites of a lithium ion conducting ceramic with a lithium salt based polymer electrolyte matrix are described. Conductivity measurements as a function of the lithium ion conducting ceramic phase content in the composite show that there is a significant increase in conductivity at approximately 40 vol% of the ceramic. The room temperature conductivity above this ceramic content is enhanced by at least 100% over that of the polymer electrolyte phase alone. It is believed that this additional contribution is substantially lithium ion conduction. The major barrier to ion-motion in these materials appears to be the interface between the polymer and ceramic. This interfacial resistance is strongly moisture-sensitive.

Enhanced lithium ion transport in PEO-based solid polymer electrolytes employing a novel class of plasticizers

A novel class of esters of benzene 1,2 dicarboxylic acids such as dioctyl phthalate (DOP), dibutyl phthalate (DBP) and dimethyl phthalate (DMP) have been used as plasticizers in high molecular weight PEO–LiClO 4 matrix (PEO=poly(ethylene oxide)) to improve the room temperature ionic conductivity of polymer–salt complex. Structural characterization was done by X-ray diffraction (XRD), thermal stability and glass transition properties were studied by DTA, and electrical (ionic) conductivities by ac-impedance spectroscopy. The XRD measurement ensures relatively low crystallinity when DOP is used as the plasticizer in the (PEO) 8–LiClO 4 matrix. It is found that the conductivity of 9.76×10 −5 S cm −1 can be achieved at room temperature for the composition (PEO) 8LiClO 4:DOP (99.9:0.1 w/o) whereas it improves an order of magnitude ( σ=4.29×10 −4 S cm −1) upon dispersing fine particles of γ-Al 2O 3 (0.01 μm) as inert fillers into the above plasticized polymer electrolyte matrix. Addition of DBP and DMP into PEO–LiClO 4 electrolyte blend provides an ionic conductivity of ∼10 −5 S cm −1 at room temperature.

Spectroscopic Analysis of Chain Conformation of Poly(propylene oxide)-Based Polymer Electrolytes

Fourier transform Raman spectroscopy has been utilized, in combination with normal coordinate analysis, to characterize chain conformational changes of amorphous poly(propylene oxide) (PPO) when used as a matrix for polymer electrolytes. Our data indicate that in the presence of salt, poly(propylene oxide) displays a characteristic Raman band at 810 cm -1 increasing in intensity with an increase in LiClO 4 concentration. 1,2-Dimethoxypropane (DMP) was found to be an excellent model for data interpretation. Both the intensity and frequency ofRaman active 1,2-dimethoxypropane vibrations were calculated. The C-C or C-O bands in the 700-900 cm -1 region were found to be particularly sensitive to chain conformational changes. The bands at 810 and 836 cm -1 were assigned to TG α T and TTT conformations of the -O-C-C-O- sequence along the backbone, respectively. Therefore an increase in intensity at 810 cm -1 directly correlates to an increase in the TG α T conformation with an increase in salt concentration. The effects of end groups on chain conformational changes were also studied since Li + can interact with both -OH end groups and ether oxygens. Poly(propylene oxide)s having hydroxy and methoxy end groups were compared. Our analyses indicate the interaction between hydroxy end groups and the lithium cation does not contribute as significantly to formation of the TG α T conformation as does the interaction between the ether oxygen and lithium cation.

Effect of additive salts on ion conductivity characteristics in solid polymer electrolytes

Effects of lattice energy of the additive salt on ionic species and ion conductivity characteristics were studied in the solid polymer electrolyte. Poly[oligo(oxyethylene) methacrylate] and several lithium salts were used as matrix and additive salt for solid polymer electrolytes, respectively. Salt and salt content deeply affected the ion conductivity characteristics as well as morphology even for amorphous type solid polymer electrolytes. The relationship between ion conductivity at constant reduced temperature ( T − T g = 90°C) and lattice energy of the additive salt was evaluated at each salt content. A different relationship was found for each salt content. Multiple ion aggregate formation was considerably affected by the salt, and was revealed to be effective to increase the ion conductivity.

Control of ionic conductivity in solid polymer electrolyte by photoirradiation

A polymer containing anthryl groups is prepared as the matrix for a Solid Polymer Electrolyte with controllable ionic conductivity by photoirradiation. The complex composed of the polymer (anthryl group content at 14 mol%) and LiClO 4(3 mol%) showed the high ionic conductivity of 6.8 × 10 −6 S cm −1 at 25°C in the dark. The conductivity change caused by photodimerization of anthryl groups is revealed to be considerably affected by the anthryl group content and T g of the matrix.