Enhancing output current in degradable flexible piezoelectric nanogenerators through internal electrode construction

Conventional piezoelectric nanogenerators (PNGs) face challenges in terms of degradation and reusability, which have negative environmental implications. On the other hand, biocompatible and degradable piezoelectric materials often exhibit lower piezoelectric response. In this study, potassium sodium niobate (KNN) powder and the biodegradable polymer poly(ε-caprolactone) (PCL) were used to fabricate piezoelectric composite films through solution casting. By constructing staggered electrodes, the total polarized charges quantity is increased, achieving a larger current output. The three-unit PNG (3-PNG) based on the composite film with 15 wt% KNN powder, reaches a maximum output current of 0.85 μA, which exhibits higher charging efficiency compared to 1-PNG. Moreover, the prepared 3-PNG can effectively harvest mechanical energy from human activities and maintain a stable output after 10,000 cycles of bending and releasing. The film exhibits complete degradation when exposed to acidic, neutral, and alkaline solutions. This research provides a promising option for environmentally friendly piezoelectric materials selected and output performance enhanced through optimized structural designs, making them more suitable for practical applications.