Self-correcting triphasic metacomposites: Decoupling thermal-electromagnetic trade-off via synergistic structural recovery and impedance optimization

The pursuit of integrated thermal management and electromagnetic interference suppression in advanced electronics is fundamentally constrained by a pore-filler conflict in composite design: functional fillers essential for microwave attenuation inevitably encroach upon the void space of porous scaffolds, severely penalizing phase change material (PCM) loading and latent heat. Here, we circumvent this deadlock via a triphasic hierarchical architecture in expanded graphite (EG) composites, wherein structural and electromagnetic functionalities are synergistically reconciled through four-component mutual compensation. The EG scaffold provides conductive pathways and pore volume; NiCo nanoparticles introduce magnetic loss but concurrently degrade the pore architecture; a solvothermally deposited flower-like TiO₂ shell counteracts this degradation by reconstructing a mesoporous network that restores the specific surface area from 6.9 to 39.6 m 2 /g, delivering a latent heat of 77.28 J/g, which is comparable to that of the NiCo-only counterpart, while the TiO₂ shell simultaneously enhances the electromagnetic absorption performance. After 100 thermal cycles, the composite retains 89.1% of its initial enthalpy, demonstrating satisfactory thermal reliability. Simultaneously, this triphasic EG/NiCo/TiO₂ ensemble establishes a “conductive–magnetic–dielectric” multi-loss system, while the infiltrated low-permittivity paraffin transcends its conventional role as a passive thermal reservoir, actively fine-tuning impedance matching to maximize wave penetration and internal attenuation. The resulting composite achieves a broad effective absorption bandwidth of 4.7 GHz at a thin thickness of 1.43 mm, alongside high thermal storage capacity and robust form stability. This work establishes a compensation-aware design paradigm that decouples thermal and electromagnetic functionalities, offering a viable route toward intelligent thermal-electromagnetic regulators for next-generation high-power, high-frequency electronics.