Scalable and low-cost lithium acetate / polyetherimide composite dielectrics exhibiting improved energy storage properties at high temperature

Polymer dielectrics with excellent energy storage properties are crucial for high-power density electronic equipment in environments such as high temperatures and strong electric fields. They play a critical role in applications including hybrid electric vehicles, electromagnetic launch devices, and photovoltaic power generation. In this paper, the small molecule compound lithium acetate (LiAc), which is low cost and exhibits good thermal stability in high-temperature environments, was selected and blended with a polyetherimide (PEI) polymer matrix at an ultra-low loading (≤0.3 vol%). LiAc has a higher electron affinity compared to PEI, which will result in a large trap energy level (Φ_e). The injected and excited electrons are trapped by strong electrostatic attraction, which suppresses carrier transport, reduces conduction losses, and improves breakdown strength in high-temperature environments. This composite dielectric exhibits better energy storage properties in high-temperature environments. The energy density of the 0.2% by volume LiAc/PEI composite dielectric reaches 3.04 J cm⁻³ at 150°C, maintaining an energy storage efficiency of approximately 90%. The research presented in this paper offers a novel approach to achieving excellent energy storage properties in polymer-based composite dielectrics operating in high-temperature environments.