Progress in percolative composites with negative permittivity for applications in electromagnetic interference shielding and capacitors

Negative permittivity (ε′ < 0), considered a supernormal property, has broadened the range of electromagnetic parameters. It provides a new principle for the design of high-end electronic devices, such as optical circuits, high-integrated chips, and electromagnetic point connectors. Negative permittivity is previously achieved by periodic array and is considered an artificial property. In recent years, the feasibility of realizing negative permittivity was demonstrated in the materials by adjusting the composition and microstructure of materials, especially in percolative composites consisting of conductive fillers and insulative matrix, which then has rapidly attracted great attention of researchers working in the field of materials science and engineering. In this review, we introduced the mechanisms of negative permittivity and summarized the recent research progress of negative permittivity performance in percolative composites with different compositions and microstructures. Besides, we introduced the potential applications of negative permittivity materials in dielectric capacitors and electromagnetic shielding. Finally, we put forward the challenges and prospects of negative permittivity performance in percolative composites, indicating the trend and focus of future research.