Salt-In-Wood Piezoelectric Power Generators with Circular Materials Design for High-Performance Sustainable Energy Harvesting

Abstract

The nanowatt-level power density of current biobased piezoelectric energy harvesters restricts their applicative potential for the efficient conversion of biomechanical energy. A high-performing, fully renewable piezoelectric device incorporating green piezo-active Rochelle salt in a laser-drilled wood template is demonstrated to form ordered crystal pillar arrays by melt crystallization. Investigating the effect of different crystal pillar configurations on the piezoelectric response, a shearing design (45°-oriented pillars) shows potential of up to 30 V and a current of 4 µA – corresponding to a 10-fold power increase compared to single-crystalline Rochelle salt. A concept of direct laser graphitization on the crystal surfaces are demonstrated using a fully renewable ink to create electrodes of low resistance (36 Ω sq−1). The entire device can be disassembled, fully recycled, and reused. This nanogenerator outperforms state-of-the-art biobased ones and competes with conventional lead-based devices in power generation while showing a significantly lower environmental footprint, as indicated by life-cycle assessment.