Inlaying ZIF-derived Co3S4 hollow nanocages on intertwined polypyrrole tubes conductive networks for high-performance supercapacitors

Abstract

Metal sulfides are promissing electrode materials for supercapacitors, but they suffer from low electrical conductivity, poor rate capability and mechanical instability. To tackle these drawbacks, here, Co3S4 hollow nanocages (HNCs) derived from ZIF-67 have been inlaid on polypyrrole (PPy) tubes, forming a Co3S4–HNCs@PPy hybrid with intertwined “Co3S4-to-PPy-to-Co3S4” conductive networks via a facile solution method. The as-synthesized Co3S4–HNCs@PPy shows outstanding electrochemical activity (1706 F g−1 at 1 A g−1) along with high rate capability (73.2% retention at 10 A g−1), significantly superior to individual Co3S4–HNCs, PPy or a physical mixture of Co3S4 and PPy. Remarkably, an asymmetric supercapacitor based on Co3S4–HNCs@PPy is capable of affording a high energy density of 50.5 W h kg−1 (at 849.1 W kg−1) with high durability (82.8% retention after 10,000 cycles). The outstanding supercapacitor property can be attributed to the synergistic advantages of the intertwined “Co3S4-to-PPy-to-Co3S4” networks including rich reactive sites, shortened charge diffusion pathway as well as enhanced charge transfer and mechanical stability. These merits make Co3S4–HNCs@PPy a promising candidate for renewable and sustainable energy storage.