A common methodology to modify both the thermal characteristics and surface properties of battery separators is the incorporation of particles. At present, the particles employed are predominantly of an arbitrary shape. The enhanced mechanical stability of particle layers comprising platelet-shaped particles is demonstrated and further evaluated on the influence of their aspect ratio (edge length to thickness) on the electrochemical properties of battery separators. Glass is selected as the particle material due to its temperature stability and the freedom of design that it offers when particles are formed directly from the melt. A parametric study of glass particle layers as function of edge length and thickness is conducted. Depending on the electrochemical characterization method, symmetrical cells with stainless steel electrodes and graphite-lithium half cells are used. Particles with an excessively high aspect ratio impede the Li+ diffusion pathway, thereby negatively affecting the performance and stability of the 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. An optimum performance can be achieved by utilizing particles with an aspect ratio of about 10 and a thickness of around 1 µm.