Flexible Zinc-Ion Hybrid Supercapacitor with High Areal Capacitance Based on a Redox Iodide Ion Electrolyte and High Mass Loading Cathode

Zinc-ion hybrid supercapacitor (ZHSC), which combines the advantages of the high power density of supercapacitors and the high energy density of batteries, is a promising energy storage device for flexible and wearable electronics. However, a relatively high areal capacitance is required in wearable devices, especially in some small and lightweight devices. Herein, a ZHSC device with superior capacitance performance is achieved by using high active mass loading cathode and adding redox iodide ions in the Zn(ClO
4
)
2
electrolyte. The ZHSC exhibits a high areal capacitance of 5.89 F/cm
²
at the current density of 0.05 A/g and a stable cycling capability of over 2000 cycles.