Abstract
Polyimide-based (PI) binders have recently garnered much attention as binders for silicon composite anodes; however, little attention has been given to the processing and handling of PI binders. To understand the interaction between silicon and a precursor-based (i.e., monomer) PI binder as a function of aging, dynamics between silicon/PI slurries as a function of UV exposure and shear rate were investigated using rheology coupled ultra-small angle neutron scattering (rheo-USANS). It was found that at all UV cure times, the PI binder acts as a dispersant at 0 Hz even though the molecular weight of the PI binder increases as a function of increasing UV exposure. As shear rate increases, all silicon/PI slurries suffer from severe agglomeration where there is more agglomeration as UV exposure increases. The resulting electrodes perform poorly in terms of both cyclability and capacity retention. This shows that there is too much binder in the slurry, and that optimization of the PI structure and amount is paramount to producing electrodes with superior electrochemical properties. These results suggest that aging will affect the reproducibility of electrodes fabricated with PI binders.
This research was supported by the U.S. Department of Energy's Vehicle Technologies Office under the Silicon Consortium Project, directed by Brian Cunningham, and managed by Anthony Burrell. This abstract has been authored by UT-Battelle, LLC, under Contract DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the abstract for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow other to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).