Lead-free linbo₃ nanowire-based nanocomposite for piezoelectric power generation

In a flexible nanocomposite-based nanogenerator, in which piezoelectric nanostructures are mixed with polymers, important parameters to increase the output power include using long nanowires with high piezoelectricity and decreasing the dielectric constant of the nanocomposite. Here, we report on piezoelectric power generation from a lead-free LiNbO₃ nanowire-based nanocomposite. Through ion exchange of ultra-long Na₂Nb₂O₆-H₂O nanowires, we synthesized long (approximately 50 μm in length) single-crystalline LiNbO3 nanowires having a high piezoelectric coefficient (d33 approximately 25 pmV^-1). By blending LiNbO₃ nanowires with poly(dimethylsiloxane) (PDMS) polymer (volume ratio 1:100), we fabricated a flexible nanocomposite nanogenerator having a low dielectric constant (approximately 2.7). The nanogenerator generated stable electric power, even under excessive strain conditions (approximately 10⁵ cycles). The different piezoelectric coefficients of d₃₃ and d31 for LiNbO₃ may have resulted in generated voltage and current for the e₃₃ geometry that were 20 and 100 times larger than those for the e31 geometry, respectively. This study suggests the importance of the blending ratio and strain geometry for higher output-power generation in a piezoelectric nanocomposite-based nanogenerator.