Block copolymer electrolytes for fuel cells and secondary batteries, the small angle neutron scattering inputs

Abstract

This paper aims at giving an overview on the importance of scattering, and more specifically neutron scattering, for probing the nanomorphology of polymer electrolytes made of block copolymers. Two types of self-assembled polymer electrolyte materials will be discussed: (i) the ionomer membranes used in fuel cell and (ii) the solid polyelectrolytes used in secondary batteries. Both are used to physically separate the electrodes in the respective electrochemical devices and are expected to have a high ion transport capacity so as good chemical and mechanical stabilities. Unfortunately, in most cases improving one property leads to the degradation of the others. Nonetheless, through block copolymers selfassembly it is possible to tackle this issue; indeed, antagonist properties can be decoupled and associated within controlled nano-morphologies. This aspect will be discussed and supported by examples based on published studies; in parallel useful scattering analytical tools and models will be presented along the paper and detailed in annex.

Introduction to soft matter and neutron scattering

“…Other architectures, and other interactions, exist, of arbitrary complexity, like the already mentioned copolymers, but this is outside the scope of this chapter. The lectures by Combet [51] and Rubatat [52] provide an idea of the infinite possibilities.…”

“…After having reviewed the main disciplines and systems of soft condensed matter, we now turn to neutron scattering, and in particular structural characterization by SANS. It is recalled that more details can be found in the following chapters, which corresponds to the lectures given in this school: after an introduction to the properties of neutrons by T. Ederth [93], a variety of applications of neutrons to soft matter systems is presented: Jérôme Combet focuses on polyelectrolytes and small-angle scattering [51], Camille Loupiac et al discuss neutron imaging and tomography applied to food science [94], and Laurent Rubatat introduces block copolymer electrolytes for fuel cells [52]. Then three chapters are devoted to dynamics and two surface techniques, respectively.…”