As a fundamental component of advanced power electronics and energy systems, capacitors are widely utilized in critical sectors such as high-voltage flexible DC transmission, new energy vehicles, pulsed power technology, aerospace, and deep-earth exploration.

However, as applications expand into extreme conditions like high temperatures and high electric fields, traditional polymer dielectrics often exhibit a sharp rise in conductivity and dielectric breakdown at temperatures above 200 C. This reduces energy storage efficiency and shortens lifespans, severely limiting their reliability in extreme environments.

To address these challenges, the research team, led by Professors Liu Wenfeng and Zhou Yao from the School of Electrical Engineering and the State Key Laboratory of Electrical Insulation and Power Equipment at Xi'an Jiaotong University (XJTU), proposed an "in situ grown nanodots" strategy.

By constructing ultra-small, highly uniform inorganic nanodots directly within the polymer matrix, the team resolved long-standing issues in traditional polymer composites, such as poor filler dispersibility, insufficient interfacial compatibility, and processing difficulties at high filler loadings. This method enables the controllable fabrication of high-quality polymer nanocomposite films.

Research indicates that these in situ grown nanodots synergistically enhance both the dielectric constant and breakdown strength at low loading levels. By introducing deep-level interfacial traps, the material suppresses charge transport under high-temperature and high-electric-field conditions.

The performance metrics of the developed polymer nanocomposite dielectric are world-leading. At 200 C, it achieved a discharged energy density of 7.03J·cm⁻³; at 250 C, it maintained 3.40J·cm⁻³ with a charge-discharge efficiency remaining above 90 percent. The performance remained stable after 50,000 cycles under the rigorous conditions of 200 C and 500 MV·m⁻¹.

This research represents a breakthrough in high-temperature energy storage for polymer dielectrics and provides fresh insights into charge transport mechanisms under high temperatures and strong electric fields. It paves the way for developing a new generation of flexible, highly reliable, and high-energy-density energy materials and devices.

The findings were recently published in the prestigious journal Energy & Environmental Science under the title Superior high-temperature capacitive energy storage performance enabled by in situ grown nanodots in polymer nanocomposites.