Flexible Self-Supporting 3D Electrode Based on 3D Graphene-PPy@Fe-MnCo2O4 Nanostructure Arrays toward High-Performance Wearable Supercapacitors

The development of high-performance flexible supercapacitors is desperately desired for application in wearable electronics, but the fabrication of a flexible self-supporting 3D electrode with light weight and high energy density remains challenging. Herein, we report an approach to fabricate the flexible self-supporting and lightweight 3D G-PPy@Fe-MnCo2O4 hierarchical electrode for flexible solid-state supercapacitors (FSSCs), which utilizes the active material 3D G-PPy as a substrate to vertically grow Fe-MnCo2O4 nanowire (NW) arrays. Importantly, the experimental results and DFT simulations indicate that Fe-MnCo2O4 NWs obtain metallic characteristics by doping Fe into a MnCo2O4 lattice, which induces the free propagation of electrons in the electrode. Thus, MnCo2O4 utilization efficiency and cycle performance are both greatly enhanced. The electrode has a high areal specific capacitance of 5136 mF cm–2 (422.4 F g–1) at 2 mA cm–2 with long-term cycle stability. The capacitance retention is about 94.7% after 7000 cycles. It presents a viable design route toward advanced wearable energy storage devices.