Analysis of Transport Restriction in Mechanically Strained Ceramic Separators

Abstract

Alternating current electrochemical impedance spectroscopy (EIS) techniques are utilized to analyze the effects of mechanically induced strain on charge transport in the inorganic ceramic separator, NPORE®. The resulting impedance data can be modeled utilizing a Bruggeman relation based equation, that considers tortuosity and porosity as functions of strain in a porous medium. Utilizing this method, the Bruggeman exponent is found for both NPORE® and Celgard 3501, a commonly used polymer separator. Comparison of the resultant Bruggeman exponents for these two separators shows that NPORE® demonstrates a superior ability to maintain transport when subject to deformation. Furthermore, NPORE® impedance demonstrates a linear response to applied stress as opposed to power law behavior ob- served in Celgard 3501. Despite consistency issues in performance, these results indicate that NPORE® is able to better maintain transport properties than Celgard 3501 when under mechanical stress and strain.