Improved Dielectric and Energy Storage Performance of BOPP Film by Decreasing Ambient Temperature

In this article, the effect of low temperature on biaxially oriented polypropylene (BOPP) is reported. The experimental results show that the films have improved dielectric and energy storage properties with the ambient temperature decreasing. The highest dc breakdown strength as high as 861.9 kV/mm is obtained at −196 °C, signifying a substantial 30.3% enhancement compared to that at 20 °C. It can be attributed to that the vitreous molecular chain structure has higher intermolecular forces to protect the molecular chain from being destroyed. Furthermore, the maximum discharge energy density attains 7.16 J/cm3, achieving a commendable efficiency of 91.08%. The migration behavior of carriers at low temperatures is inhibited, which diminishes the conductivity current. The dc conductivity is reduced by three orders of magnitude. The initial voltage of partial discharge (PD) is 1.81 times higher than that at room temperature. This article provides a new direction and insight for the development of film capacitors with high energy density and low loss.