Improvement of energy harvesting in BNBST/PDMS composites for hybrid nanogenerators

The brittleness of piezoelectric ceramics has been found to be one of the limitations for incorporating such materials into flexible and wearable energy harvesting devices. In this study, (Bi 0.47 Na 0.47 Ba 0.06 ) 0.994 Sr 0.006 TiO 3 (BNBST) ceramics were prepared by a solid-state combustion procedure using glycine as the fuel, and the effects of calcination and sintering temperature on the structure and electrical properties were investigated. BNBST powder was calcined at 650–800 °C and subsequently sintered at 1100–1200 °C for 2 h. A single-phase perovskite structure was obtained by calcining at 750 °C, while the sintered BNBST ceramics consisted of both rhombohedral and tetragonal phases. The optimal sintering condition for obtaining high density and desirable electrical properties was identified as 1175 °C with relative density (98.3%), good dielectric, ferroelectric, and piezoelectric properties (d 33 = 136 pC/N). These features suggested that this ceramic is a viable choice for use in energy-harvesting and vibration sensor developed for a flexible hybrid TENG/PENG nanogenerator. To impart mechanical flexibility and boost energy harvesting efficiency, the synthesized BNBST ceramic was mixed with polydimethylsiloxane (PDMS) matrix. Particle size distribution analysis indicated that the 10 wt% BNBST powder exhibited a relatively narrow distribution (low Span ≈ 2.24), promoting homogeneous dispersion within the PDMS matrix. The BNBST/PDMS ceramics composite with 10 wt% generated the maximum voltage (V = 137 V) and high current (I = 0.43 μA). In addition, this can generate a stable output voltage in 117 min of continuous working time and successfully powered 100 commercial LEDs.