Tailoring Particle Size and Morphology to Enhance Performance and Safety of Glass-Based Battery Separators

The thermal characteristics and surface properties of battery separators are commonly modified by the incorporation of inorganic particles into a polymeric matrix material. At present, the particles employed are predominantly of an arbitrary shape. Herein, we demonstrate significantly improved battery safety features using a glass-based separator consisting of platelet-shaped particles. Glass is selected due to its temperature stability and the freedom of design that it offers when particles are formed directly from the melt. The influence of the particles’ aspect ratio and layer stacking on the electrochemical properties was analyzed, and a parametric study of glass particle layers as function of edge length and thickness was conducted. Particles with an excessively high aspect ratio impede the Li+ diffusion pathway, thereby negatively affecting the performance and stability of the battery cell. Conversely, if the aspect ratio is insufficient, a deterioration in cell performance can be observed, particularly at elevated C-rates, due to the high specific surface area of the particles. Hence, the utilization of particles with a moderate aspect ratio of about 10 and a thickness of around 1 µm is proposed to ensure optimum performance.