Polymer Dielectrics With Interwoven Aromatic and Aliphatic Chains for High‐temperature Capacitive Energy Storage

Polymers, as the preferred material for dielectric capacitors, are required to have the ability to endure both thermal and electrical‐extremes in mainstream pulse systems and renewable energy applications. Nevertheless, the aromatic structural units in high‐temperature resistant polymers inevitably trigger significant conduction losses at high temperatures, limiting breakthroughs in capacitive performance. Here, we report a cross‑linked structure polymer, featuring an interwoven network of aromatic and aliphatic chains. We found that the aliphatic chain from polystyrene‐maleic anhydride can reduce the large interchain spacing in disordered aromatic polymers, alleviating the adverse effect of free volume on conduction loss. Meanwhile, the interlaced structure of aromatic and aliphatic chains can intercept free charges that are easily conducted along the aromatic chain. Consequently, the optimized polymer exhibits discharged energy densities of 7.24 and 5.28 J/cm 3 at 150°C and 200°C, respectively, with the charge–discharge efficiency above 90%. This work reports a scalable and cost‐effective design strategy for high‐performance dielectric polymers, with promising prospects for large‐scale production and practical applications.