Thickness Impact of PET Film on Electric Field Distribution in 1500 V Lithium-ion Battery Clusters for Energy Storage System

Lithium-ion battery energy storage systems are playing an increasingly important role in modern power systems. Increasing its DC side voltage level is beneficial for reducing costs and increasing efficiency, but imposes higher requirements on insulation. In order to strengthen insulation safety, the 1500V lithium-ion battery cluster, as the core of the energy storage system, urgently requires research on its electric field distribution. Therefore, this paper conducts simulation on the spatial potential and electric field strength distribution of the 1500V lithium-ion battery cluster using COMSOL software, taking into account the influence of PET film thickness. The sophisticated electric field simulation model encompasses a comprehensive range of geometric scales, varying across four orders of magnitude (from 10¹ to 10^-3 m). This model has effectively delineated the intricate spatial charge distribution characteristics within the aggregate of energy storage batteries. The paper explores the impact of PET film thickness, because there is a risk of thermal runaway caused by the electric breakdown of the PET film. Therefore, this paper proposes a method to increase the thickness of the PET film at the corners of the battery cells to enhance its insulation strength and thereby reduce the maximum electric field strength. This solution provides theoretical support for the insulation design of high-voltage battery energy storage systems.