Boosted ion switching at the electrode-electrolyte interfaces of architecture interdigitated flexible supercapacitors

Abstract

The pillar-array interdigitated solid-state super cap-electronics (PISSC) is a cutting-edge energy storage device with a narrow gap between isolated electrode channels, allowing for faster ionic switching and lower ionic resistance. Notably, we fabricated a symmetric supercapacitor (SnS₂‖PVA-LiClO₄‖SnS₂) using electron beam evaporation and employed physical vapor deposition (PVD) to construct thin, flexible electrodes in both pillar-array interdigitated (PISSC) and stacked (SSSC) configurations. Electrochemical performance and kinetic characteristics were evaluated for each configuration. At a scan rate of 5 mV s⁻¹, the PISSC showed notable pseudo-capacitive behavior with a superior volumetric capacitance (C_Vol) of 1410.5 F cm⁻³. We examined the switching mechanisms and kinetics under different conditions, such as OFF, ON, and V_D-states, which resulted in the quantification of AC conductivity (σ_AC), diffusion coefficient (D₀), electron transfer rate (k₀), carrier mobility (μ_C) and carrier density (n_C). The PISSC outperformed the SSSC with an AC ionic conductivity of 1.53 × 10⁻³ S cm¹, diffusion coefficient of 1.8 × 10⁻¹⁰ cm² s⁻¹ and carrier mobility of 146 cm² V⁻¹ s⁻¹, demonstrated by the operation of red LEDs connected to a 4V circuit. Additionally, the PISSC sustained excellent performance even when bent from 0 to 180°, highlighting its potential for flexible electronic applications.