Form-stable, crosslinked cellulose-based paper separators for charge storage applications

Julian Selinger; M Tauhidul Islam; Qamar Abbas; Jana B Schaubeder; Janis Zoder; Adelheid Bakhshi; Wolfgang Bauer; Michael Hummel; Stefan Spirk

doi:10.1016/j.carbpol.2024.122354

Form-stable, crosslinked cellulose-based paper separators for charge storage applications

Carbohydr Polym. 2024 Nov 1:343:122354. doi: 10.1016/j.carbpol.2024.122354. Epub 2024 Jun 1.

Authors

Julian Selinger¹, M Tauhidul Islam², Qamar Abbas³, Jana B Schaubeder⁴, Janis Zoder⁴, Adelheid Bakhshi⁴, Wolfgang Bauer⁴, Michael Hummel⁵, Stefan Spirk⁶

Affiliations

¹ Institute of Bioproducts and Paper Technology, Graz University of Technology, Inffeldgasse 23, 8010 Graz, Austria; Department of Bioproducts and Biosystems, Aalto University, Vuorimiehentie 1, FI-00076 Aalto, Finland.
² Institute for Chemistry and Technology of Materials, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria.
³ Institute for Chemistry and Technology of Materials, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria; Institute of Chemistry and Technical Chemistry, Faculty of Chemical Technology, Poznan University of Technology, Berdychowo 4, 60965 Poznan, Poland.
⁴ Institute of Bioproducts and Paper Technology, Graz University of Technology, Inffeldgasse 23, 8010 Graz, Austria.
⁵ Department of Bioproducts and Biosystems, Aalto University, Vuorimiehentie 1, FI-00076 Aalto, Finland.
⁶ Institute of Bioproducts and Paper Technology, Graz University of Technology, Inffeldgasse 23, 8010 Graz, Austria; Ecolyte GmbH, Inffeldgasse 21B, 8010 Graz, Austria. Electronic address: stefan.spirk@tugraz.at.

PMID: 39174075
DOI: 10.1016/j.carbpol.2024.122354

Abstract

In the quest for greener and more efficient energy storage solutions, the exploration and utilization of renewable raw materials is essential. In this context, cellulose-derived separators play a central role in enhancing the performance of green energy storage devices. However, these often exhibit disadvantageous porosity and limited wet strength. Here, we demonstrate a facile approach to tailor thickness (ca. 40 μm), air permeability (0.1-200 cm³ s^-1), and mechanical properties of separators by integration of up to 50 wt% microfibrillated cellulose (MFC) into paper sheets. While the MFC enhanced the formation of dense networks, these separators show a poor dimensional stability (folding and creasing) concomitant with a low strength under wet conditions, crucial for assembly and operation. Crosslinking with 1,2,3,4-butanetetracarboxylic acid (BTCA) however, led to an increase in wet strength by up to 6700 % while ensuring dimensional stability. The electrochemical performance, evaluated by impedance spectroscopy and galvanostatic cycling (7500 repetitions) showed comparable results as commercially available glass and polypropylene separators in terms of ion diffusion, charge-discharge rate performance, Ohmic loss and capacitance retention %. The approach demonstrates that disadvantages of paper-based separators in terms of dimensional stability and wet strength can be overcome by a paper technological approach using crosslinking strategies.

Keywords: Crosslinking; Energy storage; Microfibrillated cellulose; Paper-making; Separator design.