<p>The phenomena of thermal runaway and accidental deformation due to external stresses in lithium batteries or film capacitors constitute their primary failure mechanisms. Therefore, monitoring and early warning of overheating or localized strain are of great value for the safe use of lithium batteries or film capacitors; however, this function usually requires a system of multiple complex sensors. The realization of the above multiple hazards using a single sensor for monitoring and alarm functions has not been reported. Here, we exploit the thermally induced conductivity and modulus change during solid-liquid conversion of low melting point polyalloys to modulate the electronic relaxation polarization and interfacial polarization in the composites for dielectric switching, and the reduction of alloy particle spacing during bending/compressive strain can be used to generate switchable tunneling effects for insulator-conductor transition. By synergizing dielectric switching and insulator-conductor transition, the final flexible thermoplastic polyurethane elastomer/low-melting-point polyalloy composite film achieves the functional integration of multi-level overheating warning and small deformation monitoring.</p>