Title : Significant enhancement of energy storage in gradient-structured composites
Abstract:
Polymer-based dielectric composites with high power density and ultra-high energy density have become a research hotspot in response to growing environmental challenges due to their potential renewable energy storage and conversion capabilities. Lately, researchers have worked to improve the energy storage properties of materials by increasing the dielectric constant. However, dielectric constant and breakdown strength are two key factors in determining energy density. A large number of studies have shown that the improvement of dielectric constant depends largely on the high load (>50 wt%) of ceramic nanoparticles. However, the breakdown strength is also a crucial factor in determining energy density. Compared to 0 D fillers, 1D fillers allow for longer electron migration paths, resulting in a more significant improvement in the breakdown field strength of the composites. This paper outlines the design and preparation of two low-loaded ceramic nanowire/polymer gradient composites: forward-gradient and reverse-gradient structures, inspired by Josephson junctions (S-I-S). As a result, a remarkable energy density (12.2 J/cm3) and electric displacement (11.5 μC/cm2) were obtained, which exceeded the performance of the conventional single-layer film by a significant margin. The strategy of gradient structure modulation demonstrates the exceptional energy storage potential of polymer-based dielectric composites, and this approach can be widely applied to the enhancement of advanced composites with conflicting properties to achieve excellent overall performance.
