On December 16, 2025, the 2nd Special Engineering Plastics Forum was held at the Kingfa International Exchange Center in Guangzhou. Polyetherimide (PEI), a key material in the new energy storage field, has become the focus of the dielectric material sector due to its balanced and robust comprehensive properties. This semicrystalline polymer composed of aromatic rings, ether bonds, and imide rings is gradually breaking technical bottlenecks and opening a new chapter in the application of high-performance materials. Dielectric materials are the core of energy storage capacitors, directly determining the charge-discharge efficiency and safety limits of equipment. PEI's molecular structure endows it with inherent advantages: aromatic rings ensure the rigidity of molecular chains, ether bonds enhance toughness, and imide rings strengthen thermal and chemical stability, which together create its outstanding performance.

      With a dielectric constant of 3.15 that remains stable over a wide temperature and frequency range, a volume resistivity as high as 6.7×10¹⁷ ohm·cm, and negligible dielectric loss, it provides core support for the stable operation of energy storage equipment. In addition to excellent electrical properties, PEI's ability to adapt to extreme environments is equally remarkable. It can be used continuously at 150~170℃, withstand short-term high temperatures of 200℃, and has a heat distortion temperature of 220℃. It is resistant to most organic solvents, inorganic acids, and weak alkalis, and retains more than 85% of its tensile strength after being immersed in boiling water for 10,000 hours. Meanwhile, its natural flame-retardant property (oxygen index 47%, UL94-V-0 grade) and radiation resistance (retaining 94% of tensile strength after 400 megarads of cobalt ray radiation) greatly improve the safety of electrical equipment.
     Currently, the large-scale application of PEI is limited by processing difficulties: films prepared by the solution casting method have insufficient mechanical strength, while the melt extrusion casting method is prone to surface unevenness. However, technologies such as SiO₂ nanoparticle modification are gradually solving these problems. In the future, PEI is expected to expand beyond energy storage capacitors to more high-end scenarios such as electronics, electrical engineering, and medical devices. With the breakthrough of modification technologies, PEI will continue to lead the development of high-performance dielectric materials.

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