Dynamic modulation of ionic and electronic pathways in flexible SnS2-based interdigitated solid-state supercapacitors

Abstract

The interdigitated super capacitor (ISC) offers a high-efficiency energy storage approach, utilizing narrowly spaced electrode fingers to lower ionic resistance and promote faster ion transport at the electrode–electrolyte interface. A symmetric flexible device was fabricated using electron beam evaporation, where SnS₂ thin films deposited by physical vapor deposition (PVD) served as active electrodes. At a sweep rate of 5 mV s⁻¹, the ISC demonstrated pronounced pseudocapacitive behavior, delivering a high volumetric capacitance of 1129.1 F cm⁻³. We introduced and correlated the key transport properties, including the average ionic transference number (_ion), ionic conductivity (σ_AC), electron transfer characteristics (k₀ and D₀), charge carrier mobility and charge carrier density (μ_c and n_c), analyzed under OFF, ON, and V_D-state conditions. The ISC showed superior electrochemical characteristics notable values such as σ_AC ≈ 6.788 × 10⁻⁴ S cm⁻¹, D₀ ≈ 3.635 × 10⁻¹¹ cm² s⁻¹, and μ_c ≈ 65.11 cm² V⁻¹ s⁻¹. Its enhanced energy delivery capacity was further validated by powering red LEDs within a 4 V circuit, underscoring its suitability for integration into flexible and compact energy storage technologies.