Morphology Engineering of Hybrid Supercapacitor Electrodes from Hierarchical Stem-like Carbon Networks with Flower-like MoS Structures.

There is a critical need to develop high-performance supercapacitors that can complement and even rival batteries for energy storage. This work introduces a strategy to drastically enhance the energy storage performance of a supercapacitor by engineering electrode morphologies with ternary composites offering distinct benefits for the energy storage application. The electrodes were fabricated with conductive networks of carbon nanotubes (CNTs) coated with a zeolitic imidazole framework (ZIF) for high ion diffusivity and ion-accumulating molybdenum disulfide (MoS) with various morphologies. These include flower-like (fMoS), stacked-plate (pMoS), and exfoliated-flake (eMoS) structures from topochemical synthesis. CNT-ZIF-fMoS demonstrates an excellent energy density, reaching almost 80 Wh/kg, and a maximum power density of approximately 3000 W/kg in a half-cell. This is far superior to the electrodes containing pMoS and eMoS and attributed to the increased surface area and the faradaic reactivity offered by fMoS. Additionally, the CNT-ZIF-fMoS electrode demonstrates exceptional stability with an ∼78% of capacitance retention over 10,000 cycles. This work suggests that the electrode morphologies can dominate the energy storage behaviors and that the heteromaterial approach may be crucial in designing next-generation supercapacitors.