Bio-soluble Glasses for Lithium-Ion Battery Separators

Title data

Rank, Philipp ; Müllner, Sebastian ; Kerling, Vera ; Gerdes, Thorsten ; Schafföner, Stefan:
Bio-soluble Glasses for Lithium-Ion Battery Separators.
2022
Event: 26th International Congress on Glass , 3-8 July, 2022 , Berlin, Germany.
(Conference item: Conference , Poster )

Project information

Abstract in another language

Lithium-ion batteries (LIB) are one of the most important energy storage technologies for mobile devices as well as electric vehicles due to their high specific energy density [1]. However, there are safety concerns in case of overcharge or mechanical damage. The separator as a passive safety-relevant component of LIBs is placed between the two electrodes to prevent internal short-circuits. Compared to state-of-the-art polymer-based separators a glass-based separator is superior in all required properties such as higher temperature resistance and dimensional stability up to 600 °C but shows a worse size-to-weight ratio [2]. To satisfy the demand of high specific energy densities and to attract commercial interest, a separator thickness of less than 50 µm must be achieved [3]. For battery manufacturing via roll-to-roll processing alternative carrier structures need to be developed in order to meet the requirements of sufficient flexibility and tensile strength.
In this work a carrier structure based on bio-soluble glassfibers with single-fiber diameters less than 7 µm is used to lower the total thickness of the separator, whilst avoiding health issues by respirable fibers in this diameter range, guaranteeing occupational safety for workers in production and recycling sectors [4]. For this purpose melt derived glasses of three different systems (SiO2-CaO-MgO-Al2O3, SiO2-Na2O-P2O5-B2O3, P2O5-Na2O-CaO) were grinded and classified before further testing. A commercial bio-soluble glass was used as benchmark material. While previous studies have examined the bioactivity in simulated body fluids [5], the effect of the in-vitro dissolution media simulated lung fluid (SLF) has not been examined for these glasses with regard to a desired complete solubility. In this study static solubility tests of glass powder were performed in SLF at 37 °C and in a typical LIB electrolyte LP30 (1 M LiPF6 in ethylene carbonate and dimethyl carbonate) to examine the respective stability. While a preferably complete solubility in SLF is required for worker safety reason, the glasses must maintain sufficient stability in the electrolyte.
The samples were evaluated on their geometrical, morphological and chemical changes after different time points by analytical methods such as scanning electron microscopy (SEM), X-ray diffraction (XRD) and inductively coupled plasma atomic emission spectrometry (ICP-AES).