Tailored Ceramic–Metal Piezocomposite Energy Harvester with High Current Output by Controlling the Electrical Impedance

The electrical energy obtained by the piezoelectric energy harvesters (PEHs) exhibits high voltage and low current (i.e., high impedance); thus, the electrical impedance needs to be converted to a sufficiently low level. In this work, an intuitive yet logical approach that can decrease the electrical impedance has been proposed by introducing Ag particles with high conductivity into Ba0.85Ca0.15Ti0.90Zr0.10O3 (BCTZ) ceramics to form ceramic–metal piezocomposites. The results show that the formed intragranular structure allows the piezocomposites to withstand a high poling electric field; meanwhile, the addition of Ag particles significantly reduces the electrical impedance. Thus, the BCTZ/0.04Ag piezocomposite simultaneously exhibits a high piezoelectric charge constant (d33) and low electrical impedance. Furthermore, the BCTZ/0.04Ag PEH achieves a much larger current and power output at a smaller matching impedance compared to the BCTZ counterpart. This work provides an insight into solving the low-current problem of PEHs.