The realization of high permittivity and low loss via building various spatial structure composites with positive and negative permittivity layers

Abstract

The polymer composites with significantly higher permittivity and low loss tangent are vital for the advancement of advanced energy storage capacitors. However, the pursuit of elevated permittivity often comes at the cost of increased loss, imposing limitations on practical applications. In this work, we propose a novel approach of multi-layer composites, comprising positive and negative-ε′ layers. We systematically examine the influence of the relative positioning of single layers within 2-, 3-, and 5-layers structure, as well as the thickness ratio between the positive and negative permittivity layers, to unlock the potential for simultaneously achieving high permittivity, low loss, and moderate energy density. In a remarkable observation, the spatial stacking arrangement of a 5-layer composite (97679) exhibits a substantial increase in permittivity, achieving an impressive 847 as the thickness ratio reached to 1:1:20:1:1. This enhancement represents a remarkable 176-fold increase in permittivity and a one-order-of-magnitude reduction in dielectric loss compared to pristine PI matrix (ε' ≈ 4.8, tanδ ≈ 0.012 at 10 kHz). The 5-layer composite with the content of 97679 demonstrates an enhanced energy density (Ud) of up to 2.49 J/cm³ while concurrently exhibiting an exceptional efficiency (η) of 93.8%. The underlying mechanism responsible for these excellent properties presents that the BDS is influenced by the positioning of the positive-ε′ layer, and the dielectric constant is primarily governed by the arrangement of negative-ε′ layer. The strategic modulation of a multi-layer structure with positive and negative permittivity layers opens a novel design for enhancing energy storage density and tailoring dielectric performances.

Keywords

• Multi-layer composites
• Spatial arrangement
• Negative permittivity behavior
• Dielectric property