BaTiO3 internally decorated hollow porous carbon hybrids as fillers enhancing dielectric and energy storage performance of sandwich-structured polymer composite

Polymer-based materials with superb dielectric properties and energy storage performance are of essential significance in today's numerous electronic and electrical power systems. Herein, BaTiO 3 internally decorated hollow porous carbon (BT@HPC) hybrids are prepared via a unique combination of surfactant-free method and sol-gel, which are utilized as the fillers in the two outer layers of a sandwich-structured polymer composite with neat polyvinylidene fluoride (PVDF) as the central layer. Significantly improved permittivity approaches 39 (1 kHz) for the sandwich-structured composite with a low filler content of 7 wt% (~6.02 vol%) attributing to plentiful interfacial space charge polarizations (SCPs) and sophisticated microcapacitor networks constructed by BT@HPCs, while the dielectric loss still retains a low value of 0.03 owing to suppressed carrier transportation by the interfacial obstruction between adjacent layers in this hierarchical architecture. Also, enhanced energy storage density of 10.2 J/cm 3 with a high charge-discharge efficiency of 77% is achieved in the sandwich-structured composite with 1 wt% (~0.85 vol%) BT@HPC under a relative low applied electric field of 360 MV/m, to which interfacial barrier effect and redistribution of local electric field in the multilayer configuration make vital contributions. This work broadens the avenue to reinforce performance of polymer dielectrics for capacitive energy storage applications by designing specific structured particles as fillers in hierarchical architecture composite.