Poly(Vinylidene Difluoride) Soft Dendritic Colloids as Li-Ion Battery Separators
Open Access
- 1 February 2021
- journal article
- research article
- Published by The Electrochemical Society in Journal of the Electrochemical Society
- Vol. 168 (2), 020517
- https://doi.org/10.1149/1945-7111/abdfa7
Abstract
As an alternative to Li-ion battery (LIB) microporous membrane separators that are typically comprised of polyolefins, other materials and separator morphologies may yield increased cell performance. Here, we present a new class of LIB separators comprising poly(vinylidene difluoride) (PVDF)-based and highly branched, colloidal polymer particulates, called soft dendritic colloids, that are produced by shear-driven polymer precipitation within a turbulent nonsolvent flow followed by filtration. We show the morphology of the resulting PVDF particulates may be varied from fibrous dendritic colloids to thin and highly porous sheet-like particles. The use of PVDF leads to low thermal shrinkage (5% at 90 degrees C) and high tensile strength (<0.7% offset at 1000 psi), while the high porosity (up to 80%) and high particle surface area are responsible for high conductivity (1.2 mS cm(-1)) and electrolyte uptake (325%), and good cell capacity (112 mAh g(-1) in Li/LiCoO2 cell) with <10% loss after 50 cycles. Because shear-driven precipitation with filtration is a facile and versatile process to make a new class of polymeric LIB separators, soft dendritic colloids are promising candidates as separators for next-generation batteries.Funding Information
- US National Science Foundation (CMMI-1825476)
- North Carolina State University
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