Surface modification engineering on polymer materials toward multilevel insulation properties and subsequent dielectric energy storage

Polymer materials have played crucial roles in current electrical device/equipment especially in rapidly developed dielectric energy storage field, due to their excellent insulation property, low dielectric loss, lightweight, flexibility and good processability. Typical several strategies including monomer/molecule structure design, aggregation structure regulation and nanocomposite strengthening have acquired numerous processes. However, it is always ignored in existed work that insulation failure of polymer material generally starts from surface, and high-frequency electric field can greatly accelerate this failure process. Here surface modification engineering (SME) on polymer materials with a scalable, rapid and low-cost characteristic presents unique superiority in solving current problems. In this Review, we summarize various SME approaches on polymer materials and discuss introduced variations in surface morphology, physicochemical structure and charge transport behavior. We analyze how particular chemical groups anchoring, organic–inorganic deposition, physicochemical evolution and micro-nano structure design of modification surface can be modulated to obviously enhance multilevel insulation properties (from surface to interior even under high-frequency electric field) and subsequent dielectric energy storage performances. In addition, we highlight the multifunctionality and stability of modification surface on polymer materials, which examines the possibility of synergistically improving other performances like antifouling and anti-corrosion toward complicated/hash insulation scenes and advanced energy storage. Finally, we analyze current challenges in this field and offer a prospect for future development toward high-performance and large-scale practical applications.