Modulating Ionic Hysteresis to Selective Interaction Mechanism toward Transition from Supercapacitor-Memristor to Supercapacitor-Diode

The emerging ion-confined transport supercapacitors, including supercapacitor-diodes (CAPodes) and supercapacitor-memristors (CAPistors), offer potential for neuromorphic computing, brain-computer interface, signal propagation, and logic operations. This study reports a novel transition from CAPistor to CAPode via electrochemical cycling of a ZIF-7 electrode. X-ray absorption fine structure (XAFS) and electrochemical analyses reveal a shift from "ionic hysteresis" to "ionic selective interaction" in an alkaline electrolyte, elucidating the evolution of ionic devices. The CAPodes exhibit high rectification ratios, long cycling stability, and effective current blocking in reverse bias. Additionally, they are demonstrated in ionic logic circuits ("AND" and "OR" gates), with comparisons to traditional electronic diodes. This work advances the development of functional supercapacitors and iontronic devices for future capacitive computing architectures.