Aqueous-Based Polymer Electrolytes for Solid Energy Storage Systems

Abstract

The rapid growth in printable and wearable electronics has significantly increased the demand for high performance thin, flexible, and light-weight power sources. Solid-state energy storage devices, batteries and supercapacitors, enabled by polymer electrolytes are ideal solutions for such applications. In order to facilitate and promote high throughput and low cost (materials and processes) solid energy storage devices for wearable electronics, the polymer electrolytes should be highly conductive, easy to process, and possess good chemical and environmental stability in ambient conditions. We have developed a series of aqueous-based polymer electrolytes that are proton-conducting, hydroxide ion-conducting or neutral salt ion-conducting to match various cell chemistries. These aqueous-based polymer electrolytes can be applied via casting or printing methods and can potentially be implemented in roll-to-roll operations. One example is the polyacrylamide (PAM) system, in which ionic conducting species together with additives were blended into aqueous polymer matrix. In this work, three ionic conducting systems based on silicotungstic acid (SiWA) as proton-conductor [1], tetraethylammonium hydroxide (TEAOH) as anion conductor [2] and LiCl as neutral ion conductor were investigated. These three electrolytes all exhibited ionic conductivities > 10-2mS/cm and maintained stable performance under ambient conditions (room temperature and 45% relative humidity). Figure 1 shows a comparison of these 3 polymer electrolytes in terms of their ionic conductivity as a function of storage time. In this talk, an overview of these three polymer electrolytes will be provided. Materials and electrochemical characterizations of the polymer electrolytes as well as their performance in electrochemical double layer capacitors will be discussed and compared.