Free-standing Si3N4 nanowires@pyrolytic carbon membranes decorated with metal oxide nanoarrays for flexible hybrid supercapacitors

Abstract

To satisfy the increasing requirement of flexible energy storage devices, various free-standing flexible conductive substrates were developed to construct high-performance supercapacitor electrodes. In this work, free-standing, flexible and conductive Si3N4 nanowires (NWs)@pyrolytic carbon (PyC) membrane, served as nanoscale substrate, was fabricated by a two-step chemical vapor deposition (CVD) method. NiCo2O4 nanosheets (NSs) and Fe2O3 nanorods (NRs) were finally grown on Si3N4NWs@PyC membrane substrates, which were directly served as the positive and negative electrodes, respectively. The membrane electrodes possesss the structural advantages, such as the interwoven network structure of nanowires substrates and array structure of active materials, which guarantee the excellent electrochemical performance of electrodes. Additionally, the flexible solid-state hybrid supercapacitor (HSC) assembled by Si3N4NWs@PyC@NiCo2O4NSs and Si3N4NWs@PyC@Fe2O3NRs, delivered a high energy density of 74.3 Wh kg−1 at a power density of 0.8 kW kg−1, excellent cycling stability (Capacitance retention of 84.6% after 4000 cycles), and good flexibility. Impressively, this work provides a new thinking about the structural design of high-performance supercapacitor electrodes as well as expands the application field of ceramic nanowires macrostructures.