Composite polymer electrolytes for electrochemical devices

ALLOIN and C. lOJOIU, LEPMI CNRS, Grenoble Institute of Technology, France 

Key words composite polymer electrolytes, fillers, lithium batteries, PEMFC, electrochemical property, HT-PEMFC. 

Composites, i.e. filler and matrix, provide an interesting potential solution to the need for new materials. In composites, each component retains its own properties. In multi-phase materials, the overall properties depend on those of the filler and the matrix, but are also associated with specific interactions between the two materials. In the field of polymer electrolytes for electrochemical applications, the functional properties required are numerous and often incompatible, for example a polymer matrix with a high dynamic that also exhibits good mechanical properties. 

In the 1980s, several authors proposed the use of composite polymer electrolytes. The solutions they proposed depended on the electrochemical application, i.e. lithium batteries, fuel cells, etc., which determined the properties required. This chapter reviews the development and properties of composite polymer electrolytes used in lithium batteries and proton exchange membrane fuel cells (PEMFC). The effects of fillers on electrolyte properties are discussed in terms of electrochemical performance, and also in terms of polymer matrix morphology and dynamics. Data from the literature are compared in order to determine the effects of the manufacturing 

Polymer-based ion conducting materials have been of great interest to researchers in the field of lithium batteries since Armand et al proposed the use of poly(ethylene oxide) (PEO)-Li salts as a solid polymer electrolyte (SPE). In this application, the polymer electrolyte functions as a mechanical separator between the two electrodes and also as the ionic conductor. Polymer electrolytes are used in the form of thin films and may be either dry (organic solvent-free) or plasticised. A high specific energy density can be reached at medium temperature using a dry polymer electrolyte and lithium metal as the negative electrode. 

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