posted on 2016-08-18, 00:00authored byJeffrey J. Richards, Austin
D. Scherbarth, Norman J. Wagner, Paul D. Butler
Slurry based electrodes have shown
promise as an energy dense and scalable storage technology for electrochemical
flow batteries. Key to their efficient operation is the use of a conductive
additive which allows for volumetric charging and discharging of the
electrochemically active species contained within the electrodes.
Carbon black is commonly used for this purpose due to the relatively
low concentrations needed to maintain electrical percolation. While
carbon black supplies the desirable electrical properties for the
application, it contributes detrimentally to the rheology characteristics
of these concentrated suspensions. In this work, we develop a synthesis
protocol to produce inorganic oxide particles with electrostatically
adsorbed poly(3,4-ethylenedioxithiophene):polystyrenesulfonate (PEDOT:PSS).
Using a combination of small angle neutron scattering (SANS), electron
microscopy, and thin-film conductivity, we show that the synthesis
scheme provides a flexible platform to form conductive PEDOT:PSS-SiO2 nanoparticle dispersions. Based on these measurements, we
demonstrate that these particles are stable when dispersed in propylene
carbonate. Using a combination of rheology and dielectric spectroscopy,
we show that these stable dispersions facilitate electrical percolation
at concentrations below their mechanical percolation threshold, and
this percolation is maintained under flow. These results demonstrate
the potential for strategies which seek to decouple mechanical and
electrical percolation to allow for the development of higher performance
conductive additives for slurry based flow batteries.