Clustering and Percolation in Suspensions of Carbon Black
Jeffrey J Richards, Julie Beth Hipp, John K Riley, Norman J. Wagner, Paul Butler
High-structured carbon fillers are ubiquitous as the conductive additive comprising suspension-based electrochemical storage technologies. Carbon black networks provide the necessary electric conductivity as well as mechanical percolation in the form of a yield stress. Despite their critical role in determining system performance in the form of a yield stress. Despite their critical role in determining system performance, a full mechanistic understanding of the relationship between the electrical transport characteristics of the percolated, conductive networks of carbon black and the rheological properties is lacking, which hinders the rational design and optimization of flowable electrodes and the processing of electrolytes for batteries. Here, we report on the microstructural origin of the rheological and electrical properties of two commonly used conductive additives in neat proplylene carbonate. From quiescent mechanical and structural studies, we find that the gelation of these carbon black suspensions is best described by a jamming transition characterized by the arrest of a clustered fluid phase. In contrast, the temperature and frequency dependence of the ac conductivity near the jamming transition shows that mesoscale charge transport is determined by hopping between localized states and not linked to the stress-bearing network structures. This unique combination of microstructural characterization with rheological and electrical measurements enables testing prevailing theories as well as improving conductive additives with enhanced electrochemical performance.
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and Butler, P.
Clustering and Percolation in Suspensions of Carbon Black, Langmuir, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=923572
(Accessed June 4, 2023)