Decoupling elasticity and electrical conductivity of carbon black gels filled with insulating non-Brownian grains

TL;DR

This paper investigates how the electrical conductivity and elasticity of carbon black gels with non-conductive grains can be decoupled, revealing that conductivity can increase even when the gel collapses, which is important for energy applications.

Contribution

It demonstrates that insulating inclusions can decouple the relationship between elasticity and electrical conductivity in carbon black gels, a novel finding.

Findings

Conductivity and elasticity decrease together in conductive inclusions.

Insulating inclusions cause conductivity to increase despite gel collapse.

Decoupling of properties has implications for energy device design.

Abstract

A unique bistable transition has been identified in granular/colloidal gel-composites, resulting from shear-induced phase separation of the gel phase into dense blobs. In energy applications, it is critical to understand how this transition influences electrical performance. Mixing conductive colloids with conductive inclusions, we find the conductivity and elasticity move in concert, both decreasing in the collapsed phase-separated state. Surprisingly, with insulating inclusions these properties can become decoupled, with the conductivity instead increasing despite the collapse of the gel structure.