Quantifying electron transport in aggregated colloidal suspensions in the strong flow regime

• 成果类型: Article
• 署名作者: Hipp, Julie B.; Ramos, Paolo Z.; Liu, Qingsong; Wagner, Norman J.; Richards, Jeffrey J.
• 署名单位: University of Delaware; Northwestern University; Procter & Gamble
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-9989
• DOI: 10.1073/pnas.2403000121
• 发表日期: 2024-08-20
• 关键词: carbon-black suspensions; flocculated dispersions; yield-stress; BEHAVIOR; conductivity; percolation; batteries; rheology; energy; state

摘要

Electron transport in complex fluids, biology, and soft matter is a valuable characteristic in processes ranging from redox reactions to electrochemical energy storage. These processes often employ conductor-insulator composites in which electron transport properties are fundamentally linked to the microstructure and dynamics of the conductive phase. While microstructure and dynamics are well recognized as key determinants of the electrical properties, a unified description of their effect has yet to be determined, especially under flowing conditions. In this work, the conductivity and shear viscosity are measured for conductive colloidal suspensions to build a unified description by exploiting both recent quantification of the effect of flow- induced dynamics on electron transport and well- established relationships between electrical properties, microstructure, and flow. These model suspensions consist of conductive carbon black (CB) particles dispersed in fluids of varying viscosities and dielectric constants. In a stable, well- characterized shear rate regime where all suspensions undergo self- similar agglomerate breakup, competing relationships between conductivity and shear rate were observed. To account for the role of variable agglomerate size, equivalent microstructural states were identified using a dimensionless fluid Mason number, Mnf, which allowed for isolation of the role of dynamics on the flow- induced electron transport rate. At equivalent microstructural states, shear- enhanced particle-particle collisions are found to dominate the electron transport rate. This work rationalizes seemingly contradictory experimental observations in literature concerning the shear- dependent electrical properties of CB suspensions and can be extended to other flowing composite systems.