Ultrahigh-performance hybrid supercapacitors based on sodium sulfate template-derived electrodes with surface modulation

[Display omitted] •Solid-state sodium sulfate template-derived nanosheet electrodes are constructed.•Surface phosphate ions modulation effectively boosts the electrochemical features.•The active multi-component electrodes deliver splendid energy storage properties.•The assembled hybrid supercapacitor reveals high energy density and long stability.•A red LED can be lightened by the hybrid supercapacitor for up to 45 min. Exploring efficient and durable electrode materials is crucial for the mature application of high-performance hybrid supercapacitors. Herein, the Fe3O4/Fe nanoparticles with surface phosphate ions modulation (P-Fe3O4/Fe) are successfully deposited on the two-dimensional carbon nanosheets (CNS) through a solid-state sodium sulfate template-directed two-step calcination strategy. Benefiting from the synergistic effect of each component and the unique two-dimensional architecture, the prepared P-Fe3O4/Fe/CNS delivers excellent energy storage features with splendid specific capacitance (427.4 F g−1 at 1 A g−1) and outstanding cycling stability at 15 A g−1 (90.8% retention after 10,000 cycles). Following, phosphate functionalized Co9S8/CoS (P-Co9S8/CoS) nanoparticles anchored on CNS are also fabricated by the same synthesis route, which deliver a maximum specific capacity of 544.6 C g−1 at 1 A g−1 and long cyclic retention of 91.6% after 10,000 cycles at 15 A g−1. By coupling with P-Fe3O4/Fe/CNS and P-Co9S8/CoS/CNS electrodes, the assembled P-Co9S8/CoS/CNS//P-Fe3O4/Fe/CNS hybrid supercapacitor depicts an admirable energy density of 73.4 Wh kg−1 at 1041.7 W kg−1 in alkaline electrolyte and ultralong cycling stability up to 20,000 cycles with only 10.5% capacitance decay. Furthermore, the red light-emitting diode (LED) can be successfully operated for up to 45 min by the series connection of the two devices. This work proposes an efficient strategy to construct ultrahigh-performance hybrid supercapacitors with advanced sodium sulfate template-derived electrodes by phosphate functionalization.