Effects of dry powder mixing on electrochemical performance of lithium-ion battery electrode using solvent-free dry forming process

Abstract

This research examines how the morphology of the electrode powder mixture affects the structure and battery performance of lithium-ion battery electrodes fabricated using a dry electrode forming process. We demonstrate that the distribution of conductive and binding additives (CBA) on the active materials (AMs) can be controlled by adjusting the rotation speed of a dry mixer. Furthermore, we show that controlling the distribution of CBA can improve the rate performance of the batteries. The tortuosity of the CBA domain in the electrodes is analyzed from SEM images of electrode cross-sections as electronic and ionic conductive pathways. Low rotation speed dry mixing results in poor dispersion of CBA, leading to the formation of long-range conductive pathways with low tortuosity. Consequently, the capacity at high rates decreases due to fewer short-range conductive pathways between the AM particles. In contrast, high rotation speed dry mixing leads to excessive dispersion of CBA, resulting in high tortuosity in both long-range and short-range conductive pathways. As a result, the capacity decreases due to fewer efficient conductive pathways throughout the electrode. We demonstrate that medium rotation speed dry mixing achieves a favorable balance between short-range and long-range conductive pathways, providing high capacity at high rates.