Ionic Conductivity and Electrochemical Characterization of Novel Microporous Composite Polymer Electrolytes

Abstract

Lithium ion conductive polymer electrolytes have attracted much attention because of their potential application in a variety of allsolid-state electrochemical devices, particularly high energy density, rechargeable lithium/lithium-ion batteries, sensors, and electrochromic display devices. [1][2][3] Solid polymer electrolytes serve two principal roles in rechargeable Li batteries. One is as the traditional electrolyte, i.e., the medium for ionic transport, and another is as the separator which insulates the cathode from the anode. Therefore, solid polymer electrolytes must exhibit high ionic conductivity in the order of 10 Ϫ3 S cm Ϫ1 at ambient temperatures, and a good mechanical strength preferably comparable to that of porous polyethylene and polypropylene separators such as the Celgard membranes used in conventional organic solvent-based lithium batteries. They should also possess a wide electrochemical stability window preferably between 0 and 4.5 V vs. Li ϩ /Li, and good compatibility with high voltage cathodes such as TiS 2 , V 6 O 13 , LiMn 2 O 4 , LiNiO 2 , and LiCoO 2 and low voltage anodes such as lithium and Li x C 6 . A high stability of the lithium/electrolyte interface, and a high lithium ion transference number preferably close to unity, are also desirable. Among the most promising examples of solid polymer electrolytes are hybrid (gel-type or plasticized-type) electrolytes obtained by the immobilization of solutions of lithium salts dissolved in organic solvents with high dielectric constants such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), and ␥-butyrolactone (BL), in polymer matrix such as polyacrylonitrile (PAN), poly(methyl methacrylate) (PMMA), poly(vinyl pyrrolidinone) (PVP), and poly(vinylidene fluoride) (PVdF). [4][5][6][7][8][9][10][11][12] Most of these hybrid electrolytes possess some of the properties required in lithium batteries.Recently, we have reported 13 the preparation of a novel microporous composite polymer electrolyte from microemulsion polymerization, based on the microemulsion system of acrylonitrile (AN), 4-vinylbenzenesulfonic acid lithium salt (VBSLi), ethylene glycol dimethacrylate (EGDMA, as cross-linker), -methoxy poly(ethyleneoxy) 40 undecyl-␣-methacrylate (C 1 -PEO-C 11 -MA-40, as surfactant), and water. The microemulsion-polymerized membranes were extracted with ethanol, thoroughly dried in a vacuum oven at 100ЊC, and could be saturated with organic plasticizers or electrolyte solutions. The membranes saturated with EC-DMC, BL, and PC-EC had an ionic conductivity of ca. 7 ϫ 10 Ϫ5 S cm Ϫ1 , while the membranes saturated with 1 M LiClO 4 /EC-DMC (1:1 by vol-ume) or 1 M LiBF 4 /BL showed room temperature conductivities close to 10 Ϫ3 S cm Ϫ1 . Such polymer electrolytes, formed by incorporating the solutions of lithium salts in plasticizers into the microporous polymer membranes, may be called the composite polymer electrolytes (abbreviated as (CPEs).In this paper, we present a detailed investigation into the ionic conductivity and ...

Effects of potassium iodide (KI) on crystallinity, thermal stability, and electrical properties of polymer blend electrolytes (PVC/PEO:KI)

“…Then the ionic motion is opposed by a chemical potential gradient, after a time period, it has increased sufficiently to counterbalance the electric field, and then the ion migration stops. Hence the current decreases with time as the drift of ions is continuously balanced by increasing concentration gradient induced by the electrode that blocks the ions, but still active towards electrons and hence the cell gets polarized [67]. As a result the ionic current is blocked, the polarization is exclusively The ionic transference numbers of present electrolyte system, as determined from Fig.…”

Preparation of a novel composite micro-porous polymer electrolyte membrane for high performance Li-ion battery

“…This value is higher than conventional nano-composite polymer electrolyte suggesting that the critical mass fraction of liquid electrolyte filling the composite micro-porous polymer electrolyte membrane is 91.26% which is favourable for higher lithium transference. In addition, there is no obvious difference in the impedance spectrum of composite micro-porous polymer electrolyte membrane of the test cell just before and after DC-polarization studies and the relaxation time is much faster than the conventional micro-porous polymer electrolytes [26,27]. As a result, there is no significant change in the interfacial resistance during DC-polarization and hence no passive film formed on the electrode materials.…”

Investigation on Electrochemical Performance of New Flexible Nanocomposite Poly(Vinylidene Fluoride-co-Hexafluoropropylene) Polymer Electrolytes

“…For the past few years, PVdF-co-HFP-based polymer electrolytes such as solid [5], gel [6], blended [7], porous [8], and composite [9] are prepared to meet the electrochemical performance in lithium ion batteries. Gozdz et al [10][11][12][13] established the process of a porous polymer membrane by the PVdF-co-HFP polymer, and the electrolyte has been commercialized in plastic lithium ion batteries (PLiON) by using Telcordia Technologies. However, the prepared polymer membranes have faced inconvenience due to extraction of dibutyl phthalate (DBP) which also increases the cost of preparation.…”