Tailoring high-electroconductivity carbon cloth coated by nickel cobaltate/nickel oxide: A case of transition from microwave shielding to absorption

The development of electromagnetic wave (EMW) shielding and absorbing materials for flexible devices with carbon cloth and cotton cloth as the substrate has been widely reported. However, the utilization of incorrect test methods in recent reports led to the test data erroneously exhibits the actual absorption performance of the flexible absorber, which confuses the cognition of shielding and the absorbent. Moreover, previous studies are mostly based on semi-empirical rules and lack data relationships between absorption and characterization. The dominant dissipation mechanism in EMW absorbent materials demands to be resolved. Hence, we compared the EMW absorption capacity of the hierarchical carbon cloth@NiCo₂O₄/NiO hybrid via the waveguide method and the coaxial method. Specifically, the flexible absorber with integrated structure is unfavorable for incident waves to enter its interior due to its skin depth and extremely high conductivity. However, the absorbers made into a paraffin ring showed obvious optimization. Enhanced interfacial polarization is confirmed as the dominant mechanism of EMW dissipation via various characterization and analysis of electromagnetic (EM) parameters. This work provides an insight into the misunderstanding of the rational design of flexible absorbent materials for the first time, which is of great significance to the research of flexible electronic countermeasure materials.