Enhanced High-Temperature Energy Storage Performance of Polyetherimide through Maleimide Self-Crosslinking

Polymer dielectrics play a crucial role in various applications due to their low density, cost-effectiveness, flexibility, and reliability. However, their performance often declines at elevated temperatures, limiting their utilization in emerging markets. In this study, we propose a novel approach to enhance the high-temperature energy storage performance of polyetherimide (PEI), a commonly used polymer dielectric. By introducing maleic anhydride (MA) into the PEI chain structure, we induce self-crosslinking of maleimide end groups at high temperatures, thereby increasing the glass transition temperature (Tg). In addition, non-conjugated self-crosslinking regions can also inhibit charge transport in PEI chains. Experimental results demonstrate that M-PEI exhibits lower leakage current, improved dielectric properties, and significantly enhanced energy storage performance compared to pure PEI at 200°C. Notably, M-PEI with a 30% MA ratio demonstrates the best performance, achieving a maximum energy storage density of 3.45 J cm
^-3
and 90% efficiency energy storage density of 3.03 J cm
^-3
, which is twice that of PEI. Moreover, cyclic charge and discharge tests confirm the stability of M-PEI over 100,000 cycles at 200°C, highlighting its potential for practical applications. Overall, our findings suggest that the self-crosslinking of maleimide presents a promising strategy to enhance the high-temperature energy storage performance of polymer dielectrics, offering a cost-effective and scalable solution for diverse industrial applications.