Carbon black (CB), a conductive additive used in flow batteries, is proved to show thixotropy (less flowable with time under step-down in shear rate) and anti-thixotropy (more flowable with time), and this is rationalized with a qualitative mechanical model.
Significance and Impact
The fluid in flow batteries must flow, and this study shows the flow resistance is not only related to the fluid’s composition, but also shear rate and shearing time. The change in rheological properties is a direct result of the change in the structure, which guides the design of flow batteries with lower cost and higher efficiency.
- The controversial transient dynamics of CB (short-time recovery and long-time decay) is proved to be a true material response.
- The long-time decay is a result of anti-thixotropy, rather than viscoelastic stress relaxation.
The anisotropy in properties are measured.