Dispersion of a Lithium Salt in Poly(Ethylene Carbonate) Based Solid Electrolytes Processed by Melt Extrusion

ABSTRACT

Challenges arising from the safety, cost and environmental impact of lithium batteries have led to increased interest in all solid‐state batteries (ASSB). Along with enhanced safety and the replacement of liquid electrolytes, ASSB open the way to large scale production by conventional processing techniques such as extrusion. In this context, polymers, easily processable, are pointed out as attractive materials as binders in electrolytes. The extrusion of such electrolytes, including formulation, mixing and shaping was studied. A poly(ethylene carbonate) homopolymer and a poly(ethylene carbonate‐co‐ethylene oxide) copolymer were used as matrixes to disperse and encapsulate lithium salt (lithium bis(trifluoromethanesulfonyl)imide) through extrusion under conditions of controlled atmosphere, operating a laboratory extruder in a glove box. Stability of the polymers in various conditions of processing, temperature and residence time was studied by changing the monomer/Li ratio. EDX mapping of the electrolytes was used to study homogeneity in the distribution of fluorine and sulfur atoms. This was also assessed by ionic conductivity measurements. Results showed a homogeneous dispersion of the lithium salts and an almost constant ionic conductivity throughout the obtained electrolyte, with values comparable to what was reported for similar composition of electrolytes elaborated by solvent casting.