A Polymeric Mixed Conductor-Based Solid State Charge Storage Device

Organic mixed ionic and electronic conductors (OMIECs) are soft semiconducting materials that can reversibly store electronic charges in their bulk, which are stabilized by ionic charges from an electrolyte. Recent advancements in OMIEC design have improved their ion uptake and transport capabilities, increasing the number of charges per monomer unit, thus making them attractive for charge storage devices. However, aqueous electrolytes, often used within OMIECs, limit storage performance due to their narrow voltage window. In this work, we introduce an OMIEC-based charge storage device that operates with an ionic liquid gel electrolyte, which acts as a transparent, solid-state ion reservoir in a full-cell package allowing operation up to 2.4 V and has an embedded failure diagnostics system. To address the issue of self-discharge, we incorporated an O2 and H2O barrier into the device design, improving its performance in air. This cell design enables standardized conditions for screening OMIECs, without interference from parasitic reactions or electrolyte stability limitations. Through this system, we systematically tested a range of n-type OMIECs and identified the optimal anode material, resulting in a charge storage device with capacities and energy densities (~118 Wh/kg) that surpass those of current OMIEC-based systems. This work represents a step forward in developing safer, more efficient polymer-based charge storage technologies.

Organic mixed ionic-electronic conductors Charge Storage Devices Ionic Liquid Gel