A flexible polypyrrole/GelMA self-supported electrode for supercapacitors by confined interfacial electrodeposition.

The traditional polypyrrole (PPy) electrode for supercapacitors usually consists of PPy nanoparticles, carbon black and a binder. The PPy electrode inevitably suffers from structural rupture and active PPy particles' detachment during repeated doping/de-doping processes and results in low practical capacitance. Exploring the self-supported electrode without adding any binder or conductive agent is a smart and promising method to avoid the above problems. Herein, a flexible and tailorable polypyrrole/GelMA (PPy/GEL) composite film electrode was prepared via a novel confined interfacial electropolymerization at the interface of GelMA gel film and a conductive glass substrate (FTO). This method leverages spatial confinement to guide PPy growth into a continuous film, as confirmed by cross-sectional SEM analysis. This method can well confine the growth direction of the PPy chain so that PPy grows laterally to easily form a flexible and smooth two-dimensional film. The PPy/GEL-based supercapacitor not only exhibits a high areal capacitance of 260 mF cm-2 at a current density of 1 mA cm-2, which is almost 3 times higher than the pure PPy-based supercapacitor (76 mF cm-2), but also shows high cycling stability with 98% capacitance retention even after 30 000 cycles. Furthermore, the device demonstrates remarkable mechanical durability, retaining its electrochemical performance without significant degradation after being subjected to 100 repeated 180-degree folding cycles, underscoring its potential for wearable applications. This work provides a good strategy for the preparation of high performance PPy self-supported film electrodes.