ISSN:
1042-7147
Schlagwort(e):
Polymer electrolyte
;
D.c. polarization
;
Transport number
;
Limiting current fraction
;
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Maschinenbau
Notizen:
The steady state current flowing in a polymer electrolyte when a constant potential difference, ΔV, is applied to a symmetric cell of the type $$ M(s)|M^ + X^ - ,{\rm polymer}(s)|M(s) $$ has been determined as a function of the magnitude of the d.c. potential, the salt concentration and the temperature in amorphous PEO:LiCF3SO3 and PEO:LiClO4 systems.Such measurements may be used to determine a practical electrolyte parameter, the current fraction, F+, which is defined as the ratio of the current flowing when the cell is passing a steady state current following establishment of a stable concentration gradient, to the current flowing in the absence of a concentration gradient. Under certain circumstances it is possible to identify the limit of the current fraction for ΔV → 0, F+1, with the transport number of M+. More generally, measurements of F+ yield useful information about the maximum current density which may be maintained at steady state, provided that the electrolyte conductivity is known - a situation which can be rapidly attained in paractical thinfilm devices.It was found that: (i) F+1 fell very significantly as the salt concentration was increased for the two lithiumbased systems; (ii) for these systems, F+1 increased significantly with temperature at concentrations below 2.0 mol dm-3; (iii) F+1 values for the LiCF3SO3-based electrolytes were significantly higher than those for the LiClO4-based electrolytes of the same concentration; (iv) F+1 values for the LiCF3SO3-based electrolytes were independent of the molecular weight of the polymer host.
Zusätzliches Material:
6 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/pat.1993.220040214
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