High-performing polysulfate dielectrics for electrostatic energy under harsh conditions

High-capacity polymer dielectrics that operate with high efficiencies under harsh electrification conditions are essential components for advanced electronics and power systems. It is, however, fundamen-tally challenging to design polymer dielectrics that can reliably withstand demanding temperatures and electric fields, which neces-sitate the balance of key electronic, electrical, and thermal parame-ters. Herein, we demonstrate that polysulfates, synthesized by sulfur(VI) fluoride exchange (SuFEx) catalysis, another near-perfect click chemistry reaction, serve as high-performing dielectric poly-mers that overcome such bottlenecks. Free-standing polysulfate thin films from convenient solution processes exhibit superior insu-lating properties and dielectric stability at elevated temperatures, which are further enhanced when ultrathin (-5 nm) oxide coatings are deposited by atomic layer deposition. The corresponding elec-trostatic film capacitors display high breakdown strength (>700 MV m-1) and discharged energy density of 8.64 J cm -3 at 150 degrees C, outper-forming state-of-the-art free-standing capacitor films based on com-mercial and synthetic dielectric polymers and nanocomposites.