Abstract
Why do battery researchers use 10–20 wt% binder in research cells when commercial chemistries use much less? This report seeks to explore this question by understanding the ordering and structure of polyimide binder with a silicon/pitch-carbon black electrode system. Correlating the effect of binder concentration on electrode architecture and electrochemical properties is vital to enhancing silicon anode cycle and calendar life. Using ultra-small angle neutron scattering (USANS) and binder adsorption isotherms an optimal region of polyimide (PI) binder coverage was found. Further, there is a preferential adsorption of PI to carbon black that has to be completed before PI binds to the silicon. Optimizing the concentration of binder leads to a 50% increase in capacity due to the optimization of binder-silicon-carbon interactions.
| Original language | English |
|---|---|
| Article number | 230914 |
| Journal | Journal of Power Sources |
| Volume | 520 |
| DOIs | |
| State | Published - Feb 1 2022 |
Funding
From the binder adsorption isotherms shown in Fig. 1, there are 3 approximate P84 adsorption regimes. To evaluate the binder/silicon structure of the slurries in the various concentration regimes, Si@pitch slurries were prepared with 0.5 wt%, 5 wt%, and 10 wt% P84 for ultra-small angle neutron scattering (USANS) studies (Fig. S4). Carbon black was not introduced in the USANS slurries as the scattering from carbon black cannot be contrast matched and instead would overwhelm the signal from the binder, therefore we focus only on the Si@pitch-PI interactions. Figs. 3 and 4 present representations of the agglomerate and aggregate structure of Si@pitch 90:10 and 50:50 slurries with varying amounts of P84 binder as extracted from fitting of the USANS data from the correlation length model (CLM) described by Equation (2) (See Supporting Information for fits and values).This research (MKBT, BLA, GMV) 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. A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by Oak Ridge National Laboratory (MD and LH). The ultra-small angle scattering measurements were done using the USANS instrument at the Spallation Neutron Source. This work benefited from the use of the SasView application, originally developed under NSFaward DMR-0520547. SasView contains code developed with funding from the European Union's Horizon 2020 research and innovation programme under the SINE2020 project, grant agreement no. 654000. The authors thank Paul Dodson and Bill Aronoff for their invaluable help with the GPC. This manuscript 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 article 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). This research (MKBT, BLA, GMV) 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. A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by Oak Ridge National Laboratory (MD and LH). The ultra-small angle scattering measurements were done using the USANS instrument at the Spallation Neutron Source. This work benefited from the use of the SasView application, originally developed under NSFaward DMR-0520547. SasView contains code developed with funding from the European Union's Horizon 2020 research and innovation programme under the SINE2020 project, grant agreement no. 654000. The authors thank Paul Dodson and Bill Aronoff for their invaluable help with the GPC. This manuscript 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 article 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 ).
| Funders | Funder number |
|---|---|
| DOE Public Access Plan | |
| USANS | |
| United States Government | |
| U.S. Department of Energy | |
| Office of Science | |
| Oak Ridge National Laboratory | DMR-0520547 |
| Horizon 2020 Framework Programme | |
| Horizon 2020 | DE-AC05-00OR22725, 654000 |
Keywords
- Adsorption isotherms
- Polyimide
- Silicon anode
- Slurry processing and fabrication
- Ultra-small angle neutron scattering (USANS)