posted on 2024-02-28, 18:04authored byZhizhan Dai, Jiangheng Jia, Song Ding, Yiwei Wang, Xiangsen Meng, Zhiwei Bao, Shuhong Yu, Shengchun Shen, Yuewei Yin, Xiaoguang Li
The commercial capacitor using dielectric
biaxially oriented polypropylene
(BOPP) can work effectively only at low temperatures (less than 105
°C). Polyphenylene oxide (PPO), with better heat resistance and
a higher dielectric constant, is promising for capacitors operating
at elevated temperatures, but its charge–discharge efficiency
(η) degrades greatly under high fields at 125 °C. Here,
SiO2 layers are magnetron sputtered on both sides of the
PPO film, forming a composite material of SiO2/PPO/SiO2. Due to the wide bandgap and high Young’s modulus
of SiO2, the breakdown strength (Eb) of this composite material reaches 552 MV/m at 125 °C
(PPO: 534 MV/m), and the discharged energy density (Ue) under Eb improves to 3.5
J/cm3 (PPO: 2.5 J/cm3), with a significantly
enhanced η of 89% (PPO: 70%). Furthermore, SiO2/PPO/SiO2 can discharge a Ue of 0.45 J/cm3 with an η of 97% at 125 °C under 200 MV/m (working
condition in hybrid electric vehicles) for 20,000 cycles, and this
value is higher than the energy density (∼0.39 J/cm3 under 200 MV/m) of BOPP at room temperature. Interestingly, the
metalized SiO2/PPO/SiO2 film exhibits valuable
self-healing behavior. These results make PPO-based dielectrics promising
for high-temperature capacitor applications.