3D-Printed Highly Stretchable Conducting Polymer Electrodes for Flexible Supercapacitors

Recent advances in the development of wearable, implantable, and bio-integrated electronic devices have increased the demand for stretchable and flexible energy storage devices that can deliver high degrees of mechanical deformability. However, the fabrication of fully flexible electronics with both satisfactory electrochemical performance and mechanical stretchability remains a significant technological hurdle. In this work, by synergistically combining theoretical structural design and 3D printing, additive-free free-standing stretchable electrodes with different negative Poisson's ratio (NPR) structures have been developed based on a poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) ink. Through tensile tests and finite element analyses (FEA), the stretchable electrode with a well-designed arc-shaped NPR structure can effectively reduce the peak strain, resulting in excellent flexibility (up to 180°) and stretchability (maximum elongation 150%). Through further integration of carbon nanotubes (CNTs), the 3D printed hybrid polymer/CNT electrode exhibits enhanced electrochemical performance with a high area capacitance of 990 mF cm−2. The as-fabricated quasi-solid-state symmetric supercapacitor not only achieves a satisfactory energy density and maintains excellent capacitance retention of 74.7% after 14 000 cycles, but also shows promising mechanical properties by maintaining stable power output even when being extremely deformed. The strategy proposed here offers promising opportunities in developing novel deformable electrodes for integrated wearable energy storage devices in various applications.