Flexible conductive polymer composites (CPCs) are creating new opportunities in soft electronics and their applications. Compared with CPCs based on unary filler systems, CPCs with binary fillers have plenty of advantages in mechanical and electrical properties due to the synergistic superiority of fillers. Herein, a new kind of flexible binary fillers CPC composed of nano-sized carbon black (CB) particles and micro-sized silver (Ag) platelets uniformly dispersed in polydimethylsiloxane (PDMS) is reported and named Ag-CB-PDMS. A synergistic conductive network structure based on observation of scanning electron microscope (SEM) is proposed. The conductivity is approximately 20 times higher than that of unary filler system, with a threefold improvement in its stability. Through the regulation of the filler concentration, the temperature coefficient can be adjusted, and the resistance is insensitive to temperature when silver and carbon black concentrations are 15 and 18 wt%, respectively. Meanwhile, Ag-CB-PDMS retains good flexibility and shows excellent piezoresistive characteristics. During compression-release cycles, Ag-CB-PDMS exhibits excellent stability, good repeatability (1000 cycles), and fast response time (52 ms). A temperature--pressure sensor is constructed based on Wheatstone bridge for real-time monitoring of lithium-ion batteries (LiBs) to achieve early safety warning. [ABSTRACT FROM AUTHOR]