Integrating Hybrid Supercapacitors With Batteries: Unravelling the Mechanism in Zn-I 2 /MnO 2 Systems

Supercapatteries, integrating supercapacitors and batteries, offer a promising route to combine high power and energy density. This study decouples their charging behavior by constructing hybrid (Zn//AC) and symmetric (AC//AC) supercapacitors coupled with I2/MnO2batteries. We identify a stepwise mechanism where supercapacitor charging precedes battery reactions. The Zn//AC configuration successfully integrates with the I₂ battery, while the symmetric AC//AC system fails due to the shuttle effect. The zinc anode enables both efficient capacitive charging and stable battery operation. Furthermore, charge transfer between the supercapacitor and battery subsystems is observed, highlighting their dynamic interplay. These findings provide key insights for designing integrated, high-performance energy storage systems with tunable capacitive and battery-like behavior.