The electrical resistivity of CB–polymer piezoelectric hybrid nanocomposites: Experimental and micromechanical studies

Hybrid polymer nanocomposites combining conductive and piezoelectric phases hold promising applications for flexible sensing and energyharvesting, yet their coupled transport mechanisms remain unclear. Here, we investigate the electrical resistivity of carbon black (CB)–potassium sodium niobate (KNN)–epoxy composites through systematic experiments and micromechanical modeling. Resistivity measurements across varying CB contents reveal a sharp percolation-driven decrease, while incorporation of KNN preserves piezoelectric functionality but elevates resistivity compared with binary CB/epoxy systems, enabling a tunable balance between conductivity and sensitivity. To elucidate this interplay, we propose a modified simplified unit cell model that integrates interphase conductivity and quantum tunneling resistance at CB–epoxy interfaces. The model reproduces experimental data with <5 % overall coefficient of variation and clarifies how KNN dispersion modulates percolation thresholds and tunneling efficiency. This combined framework establishes design guidelines for lead-free, high-performance piezoelectric nanocomposites and supports their future application in wearable health monitoring and structural sensing.