A detailed overview on interface design and control in polymer based composite dielectrics for energy storage applications.

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Energy storage materials are urgently demanded in modern electric power supply and renewable energy systems. The introduction of inorganic fillers to polymer matrix represents a promising avenue for the development of high energy density storage materials, which combines the high dielectric constant of inorganic fillers with supernal dielectric strength of polymer matrix. However, agglomeration and phase separation of inorganic fillers in the polymer matrix remain the key barriers to promoting the practical applications of the composites for energy storage. Here, we developed a low-cost and environmentally friendly route to modifying BaTiO3 (BT) nanoparticles by a kind of water-soluble hydantoin epoxy resin. The modified BT nanoparticles exhibited homogeneous dispersion in the ferroelectric polymer poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) matrix and strong interfacial adhesion with the polymer matrix. The dielectric constants of the nanocomposites increased significantly with the increase of the coated BT loading, while the dielectric loss of the nanocomposites was still as low as that of the pure P(VDF-HFP). The energy storage density of the nanocomposites was largely enhanced with the coated BT loading at the same electric field. The nanocomposite with 20 vol % BT exhibited an estimated maximum energy density of 8.13 J cm(-3), which was much higher than that of pure P(VDF-HFP) and other dielectric polymers. The findings of this research could provide a feasible approach to produce high energy density materials for practical application in energy storage.

A novel microwave absorbing material with Ti3C2MXene nanosheets.

An ultra-high discharged energy density P(VDF-HFP) capacitor is achieved by introducing a small fraction of Na0.5Bi0.5TiO3 nanofibers.

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Thermal-stable dielectric capacitors with high energy density and power density have attracted increasing attention in recent years. In this work, (1 – x)­Bi0.5Na0.5TiO3–xNaTaO3 [(1 – x)­BNT–xNT, x = 0–0.30] lead-free relaxor ferroelectric ceramics are developed for capacitor applications. The x = 0.20 ceramic exhibits superior thermal stability of discharged energy density (W D) with a variation of less than 10% in an ultrawide temperature range of −50 to 300 °C, showing a significant advantage compared with the previously reported ceramic systems. The W D reaches 4.21 J/cm3 under 38 kV/mm at room temperature. Besides, a record high of power density (P D ≈ 89.5 MW/cm3) in BNT-based ceramics is also achieved in x = 0.20 ceramic with an excellent temperature insensitivity within 25–160 °C. The x = 0.20 ceramic is indicated to be an ergodic relaxor ferroelectric with coexisted R3c nanodomains and P4bm polar nanoregions at room temperature, greatly inducing large maximum polarization, maintaining low remnant polarization, and thus achieving high W D and P D. Furthermore, the diffuse phase transition from R3c to P4bm phase on heating is considered to be responsible for the superior thermal stability of the high W D and P D. These results imply the large potential of the 0.80BNT–0.20NT ceramic in temperature-stable dielectric capacitor applications.