Exploring modification strategies to enhance energy storage performance of BOPP dielectric films

In current industrial DC and AC applications, highly reliable film capacitors are the workhorses among the passive components. Dielectric polymer films with a superior energy storage performance occupy a crucial position in the development of such metallized film capacitors. Biaxially oriented polypropylene (BOPP) is a progressive available dielectric material due to its distinguished dielectric properties and demonstrated manufacturing technique. However, BOPP films are affected by an excessive conduction loss and reduced breakdown strength at elevated temperatures, making it significantly important to achieve modification methods for reducing energy loss and increasing efficiency. Therefore, this review aims to carry out a thorough exploration of recent investigations for enhancing high-temperature capacitive energy storage performance of BOPP films. While, initially, fundamentals of dielectric capacitors are introduced, followed by a comprehensive inspection of the relationship between the BOPP microstructure and dielectric properties, attention is focused on various modification strategies for enhancing energy storage performance of BOPP films, which fall into two categories of pre-stretching and post-stretching treatments. Benefits and drawbacks of different approaches are closely discussed, and ultimately, challenges and future prospects are outlined for the ongoing research.