Water-Based Glass-Platelet Coatings for Polyethylene Separators : Faster Wetting, Higher Thermal Stability, and Improved Li-Li Cycling

Titelangaben

Rank, Philipp ; Müllner, Sebastian ; Gerdes, Thorsten:
Water-Based Glass-Platelet Coatings for Polyethylene Separators : Faster Wetting, Higher Thermal Stability, and Improved Li-Li Cycling.
2026
Veranstaltung: GDCh Electrochemistry 2026 , 22-25 September 2026 , Bayreuth, Germany.
(Veranstaltungsbeitrag: Kongress/Konferenz/Symposium/Tagung , Vortrag )

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Abstract

Meeting the growing demand for high-power batteries requires cell components that simultaneously enable high performance, improved safety, and low manufacturing cost. The separator is a key component. It must be thin and lightweight to preserve energy density, yet robust against thermal abuse, mechanical damage, and lithium dendrite growth, especially when advanced electrodes such as lithium metal are used.
Commercial polyolefin separators in lithium-ion batteries often show insufficient electrolyte wettability, which can impede efficient electrolyte filling during cell assembly, resulting in increased manufacturing time and cost. Additionally, their limited thermal stability leads to safety concerns at elevated temperatures. Herein, we present an aqueous, colloidal coating route to hybrid polyethylene (PE) separators using glass particles as the inorganic phase and styrene-butadiene rubber (SBR) as a thermally robust and water-based binder.
Platelet-shaped particles were selected to form a coating layer with a brick-and-mortar-like structure. Because excessive binder can compromise the separators’ pore structure and increase ionic resistance, the binder fraction in the coating was systematically controlled to ensure particle fixation without compromising ionic transport by deterioration of the pore structure. The hybrid separators, with an optimized SBR content of 1 wt.% in the coating, have been demonstrated to exhibit high porosity and instantaneous electrolyte wetting. In addition, a 25 K increase in the onset temperature of shrinkage compared to the uncoated PE separator has been observed. From the electrochemical point of view, coatings based on glass platelets yield an increase in ionic conductivity and deliver improved long-term cycling stability in Li-Li symmetric cells at current densities up to 3C, in comparison to the uncoated reference. Overall, the combination of shape-engineered glass particles and minimal binder loading provides a scalable strategy to multifunctional, sustainable separators that accelerate cell assembly while enhancing thermal and electrochemical robustness.