A gated highly variable pseudocapacitor based on redox-window control (G-CAPode)

Abstract

Iontronic architectures operate via multiple ions or redox processes mimicking neural systems capable to operate with complex ions and biological transmitters with high energy efficiency. Recently, ultracapacitors have emerged as novel iontronic switchable devices with a high on/off ratio. We propose a novel iontronic device offering flexible control of the current output of a switchable electrochemical capacitor diode (CAPode) by introducing an additional “gate” electrode. This device mimics field-effect transistor (FET) semiconductors in controlling current output and recovers energy consumed during the forward charging, marking a significant breakthrough. A recently developed unidirectional CAPode system (Ni₃Bi₂S₂@Ni I 1 mol L^-1 KOH I AC@Ni) serves as the “working” capacitor (W-Cap) in the novel architecture. The proposed G-CAPode (gate-controlled CAPode) features a third voltage-controlled connection between the “gate” and the counter electrode of the W-Cap. By varying this third voltage channel the electrodes of W-Cap are shifted in potential toward negative or positive potential windows. Hence, by external voltage control the rectification ratios and blocking efficacy can be tuned which is essential for fully controlling the output signal in logic gates. A new circuit monitors the current and potential distribution of the NOT gate: The G-CAPode system exhibits transistor-like characteristics with a −1.2 V bias. This investigation highlights the versatility of the G-CAPode system across applications where transistor-like behavior and accurate current regulation are beneficial, promising advancements in ionologic devices, sensors, and energy storage systems.