Collaborative Research: Co-Extrusion of Organic-Inorganic Colloidal Inks for Energy Conversion Applications

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Energy storage (batteries) and energy conversion systems (fuel cells) are composed of planar, layered structures often referred to as membrane electrode assemblies. One of the primary limitations with these systems is the multi-step materials processing associated with manufacturing. Extrusion manufacturing methods offers the opportunity to combine multiple materials systems at once for integrated and engineered part development for electrochemical systems. One of the key challenges in achieving this is the engineering of colloidal inks capable of producing uniform parts with controlled properties. In this project, colloidal inks, which can be described as semi-solid or semi-liquid, consist of platinum coated carbon particles in a polymeric base. The work will investigate how these complex inks behave under extrusion conditions, and how they interface with other co-extruded inks. A fundamental understanding about co-extrusion processing of colloidal inks will potentially enable facile and scalable manufacturing methods for multi-layered structures and components common in electrochemical systems. Moreover, colloidal co-extrusion has broad application in the manufacturing of novel composite materials, organic electronics, thermoelectric, photovoltaics, bio-materials, and batteries. In addition to providing graduate and undergraduate students research experiences, this project will contribute towards broadening manufacturing education in K-12 programs in the Nashville and Atlanta areas. Complex material systems are rarely processed using co-extrusion based approaches due to the inherent difficulties which arise due to mechanical and fluid induced instabilities. These instabilities are well documented and broadly understood for single component extrusion processing (e.g. polymers), but there have been limited studies that probe multi-component colloidal materials. The research objective of this work is to explore the interactions between soft and hard colloids during co-extrusion processes. The work specifically seeks to understand how interactions between components in an ink affects viscoelastic properties and promote or dampen ink mixing or delamination mechanisms. This work will utilize advanced characterization techniques (scattering and microcopy) to probe colloid structure information and define unique constitutive equations to describe functional properties in extruded colloidal inks. Moreover, these constitutive relationships will be used to engineer colloidal inks that promote interfacial stability during extrusion processes. This work is fundamental in nature and the product of this work is relevant to the manufacturing community as well as the rheological, electrochemical, and colloidal science communities.