Associate Professor Zhengdong Wang from the School of Mechanical and Electrical Engineering, Xi'an University of Architecture and Technology, developed a novel epoxy film with excellent comprehensive properties by introducing rigid phenyl and flexible etherified methylene side chains, providing insights for the material design of high-performance polymer film capacitors. The research was recently published in the journal Materials Science & Technology.
Polymer dielectrics, with their advantages of high power density, low cost, and strong processability, are widely used as energy storage materials in capacitors for rapid high-power regulation in smart grids and AC-DC conversion in electric vehicles. To achieve rapid regulation of high power in smart grids due to the integration of distributed新能源发电 into the power system, which increases the load on distributed grids and complicates supply and demand control, capacitors with higher energy storage density and lower dielectric loss are required. In AC-DC conversion applications, the high operating temperature of electric vehicle inverters places greater demands on the heat resistance of capacitors. This study introduces flexible etherified methylene chains into the side chain positions of rigid molecular chain cross-linking networks, which significantly improves their dielectric constant and mechanical flexibility. Meanwhile, due to the minimal influence of flexible side chains on the stability of the cross-linked network structure, low dielectric loss and high energy storage efficiency can be maintained at high temperatures. For example, under room temperature 420 kV/mm conditions, the epoxy film in the study exhibits an energy storage density of 7.06 J/cm3 and a charge-discharge efficiency of 85%. Under the operating conditions of 200 kV/mm and 110 °C in electric vehicle applications, the fabricated film still achieves an energy storage density of 1.5 J/cm3 and a charge-discharge efficiency of 86%, which is three times that of BOPP, the most widely used commercial polymer dielectric material.
Relevant paper information: https://doi.org/10.1016/j.jmst.2023.10.026
