Paper Number
SC47 

Session
Suspensions and Colloids

Title
Study of the rheology and wall slip of carbon black suspensions for semi-solid flow batteries

Presentation Date and Time
October 9, 2014 (Thursday) 9:05

Track / Room
Track 1 / Millennium Hall

Authors (Click on name to view author profile)

1. Helal, Ahmed (MIT, Mechanical Engineering)
2. Smith, Kyle (MIT, Materials Science & Engineering)
3. Fan, Frank (MIT, Materials Science & Engineering)
4. Chen, Xin wei (MIT, Materials Science & Engineering)
5. Nóbrega, João Miguel (University of Minho, Department of Polymer Engineering)
6. Chiang, Yet-Ming (MIT, Materials Science & Engineering)
7. McKinley, Gareth H. (Massachusetts Institute of Technology, Department of Mechanical Engineering)

Author and Affiliation Lines (in printed abstract book)
Ahmed Helal¹, Kyle Smith², Frank Fan², Xin wei Chen², João Miguel Nóbrega³, Yet-Ming Chiang², and Gareth H. McKinley^1
1Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139-4307; ²Materials Science & Engineering, MIT, Cambridge, MA 02139; ³Department of Polymer Engineering, University of Minho, Guimarães, Portugal

Speaker / Presenter 
Helal, Ahmed

Text of Abstract
Electrolyte suspensions containing carbon black nanoconductor particles (KetjenBlack) show promise for novel semi-solid flow cell designs. Characterizing the rheology and wall-slip behavior of these suspensions is crucial to estimate mechanical efficiency losses, optimize cell performance, and guide cell design. In these suspensions, the carbon black particles form a fractal network that percolates at low volume fractions (<0.5 vol%) and exhibits a gel-like behavior resulting in complex rheology (yield stress, shear thinning, finite size effects) coupled with wall slip. In this work, we will present experimental methods to characterize both the shear rheology (under steady and small amplitude oscillatory shear) and the slip behavior of these suspensions, using a torsional rheometer with a plate-plate geometry. The results obtained show that these suspensions exhibit a linear dependence of the slip velocity on shear stress and a critical shear stress for the onset of slip. A systematic study of the effect of the carbon black loading on the suspension yield stress, slip velocity, elastic modulus and conductivity will be performed and used to aid the design of future flow cells.