Journal Article Review energy density polymer dielectrics Polymers Research Support, Non-U.S. Gov't breakdown self‐healing capacitive sensors capacitors carbon fibers composites conduction loss core-shell design design of interface structures dielectric capacitors dielectric loss dielectric property electrical/mechanical damage electron displacement energy storage energy storages filler-clusters geometric design high-temperature energy storage high‐temperature energy storage high‐temperature polymer dielectrics irradiation microstructures nanocomposites nanodielectrics