3D printing encouraging desired in-situ polypyrrole seed-polymerization for ultra-high energy density supercapacitors

The tireless pursuit of supercapacitors with high energy density entails the parallel advancement of well-suited electrode materials and elaborately engineered architectures. Polypyrrole (PPy) emerges as an exceedingly conductive polymer and a prospective pseudocapacitive materials for supercapacitors, yet the inferior cyclic stability and unpredictable polymerization patterns severely impede its real-world applicability. Here, for the first time, an innovative seed-induced in-situ polymerization assisted 3D printing strategy is proposed to fabricate polypyrrole-reduced graphene oxide/PVDF-HFP (PPy-rGO/PH) electrodes with controllable polymerization behavior and exceptional areal mass loading. The preferred active sites uniformly pre-planted on the 3D-printed graphene substrates serve as reliable seeds to induce efficient polypyrrole deposition, achieving an impressive mass loading of 185.6 mg cm−2 (particularly 79.2 mg cm−2 for polypyrrole) and a superior areal capacitance of 25.2 F cm−2 at 2 mA cm−2 for a 12-layer electrode. In agreement with theses appealing features, an unprecedented areal energy density of 1.47 mW h cm−2 for a symmetrical device is registered, a rarely achieved value for other PPy/rGO-based supercapacitors. This work highlights a promising route to preparing high energy density energy storage modules for real-world applications.