Factors Controlling Ionic Conductivity of Plasticized and Non-Plasticized Crosslinked Polyether Electrolytes
- PDF / 346,812 Bytes
- 6 Pages / 420.48 x 639 pts Page_size
- 61 Downloads / 207 Views
FACTORS CONTROLLING IONIC CONDUCTIVITY OF PLASTICIZED AND NONPLASTICIZED CROSSLINKED POLYETHER ELECTROLYTES DOUGLAS R. MACFARLANE, JEFFREY M. HEY AND MARIA FORSYTH Department of Chemistry, Monash Clayton, Victoria 3168, Australia
University,
ABSTRACT
A series of elastomeric (urethane crosslinked) polyether electrolytes have been prepared in order to investigate the influence on conductivity of crosslink density, length of uninterrupted polyether chain, number of side chains and plasticizer content. Crosslink density was found to only weakly influence conductivity, but had the expected major effect on elastic modulus. Increases in uninterrupted polyether chain length were also found to enhance conductivity. The number of side chains (acting as an internal plasticizer) was not found to have a marked effect on conductivity within the range studied. The highest room temperature conductivity observed in these non-plasticized elastomers was 3 x 110-5 Q-cm- 1 . Addition of a low molecular weight plasticizer such as tetraglyme was found to markedly increase the conductivity and lower Tg. The highest room temperature conductivity observed in 50% plasticized elastomeric materials was 10-3 - 1 cm-1. INTRODUCTION Solid polymer electrolytes have been proposed as replacements for traditional liquid electrolytes in a number of applications including electrochemical cells, for example batteries and electrochromic devices(I). Such applications demand not only a sufficient level of conductivity in the electrolyte such that internal voltage drops are not significant, but also material properties appropriate to the requirements of the application. For example, where the solid polymer electrolyte is intended for use in a battery and the electrolyte is required to maintain separation, both physical and electrical, of the electrodes, then the elastic modulus becomes of importance. Since the material properties may be related to the chemical structure of the polymer in a similar way to the ionic conduction properties, it becomes of importance to establish what inter-relationships exist, if any, between the various properties. In this work we have investigated the conductivity and elastic modulus of a number of urethane crosslinked polyether network solid polymer electrolytes in order to establish which polymer structural features influence these important properties of the material. A considerable degree of structural variety is possible within this family of material as a result of the large range of polyether type polymers that are available. By incorporation into the structure of suitable quantities of di- and tri- functional hydroxy terminated polyethers we have investigated the effect of changes in crosslink density and uninterrupted polyether chain length on conductivity. In addtion to this, incorporation of mono and non hydroxy terminated polyethers enabled a study of an internal plasticizer effect and the effect of oligomeric ether plasticizers. EXPERIMENTAL Solid polymer electrolyte samples were prepared by dissolving the appr
Data Loading...
