Direct-ink-writing of multistage-pore structured energy collector with ultrahigh ceramic content and toughness

Polymer-based piezoelectric composites with flexibility, lightweight and stable energy output play an indispensable role in self-powered portable electronic equipment. The addition of high-content ceramics to form three-dimensional porous structures can greatly improve the piezoelectric properties of the composites but adversely affects the flexibility and mechanical properties of the materials. In this study, multistage-pore structured polydimethylsiloxane (PDMS)/barium titanate (BT) composites with ultrahigh BT content and super toughness were manufactured through direct-ink-writing technology. The construction of multistage-pore structures with ultrahigh ceramic content greatly improved the mechanical and piezoelectric properties of the composites. The 80 wt% BT-filled composite shows a high open-circuit voltage of 45 V and short-circuit current of 2.7 μA with a stable output after 2500 voltage cycles. Furthermore, from the cyclic compression test to the strain of 30%, the ultimate stress only decreases by 12% after 2000 cycles, among which 95% occurred in the early stages (the first 100 cycles), which demonstrating stable and repeatable elasticity of ultrahigh BT-filled composite. This study provides insights for preparing high-ceramic-content piezoelectric composites through 3D printing technology for energy collection in wearable devices.