Biomimetic organohydrogel electrolytes for high-environmental adaptive energy storage devices

Abstract

Conventional hydrogel electrolytes suffer from the following notable defects: (a) water molecules inevitably evaporate from hydrogels under ambient conditions, and high temperature accelerates the dehydration process, leading to deterioration of electrochemical performance; (b) at subzero temperatures, the water existed in gel matrix would freeze and inhibit the ion transportation of hydrogel electrolyte; (c) while operating under water, the gel electrolyte absorbs water and swells, resulting in the loss of adhesion between electrodes and electrolyte. The exchange of solutes causes the decrease of ion concentration and depresses the device performance. These environmental effects fundamentally limit the long-term stability and utilization of aqueous flexible energy storage devices under severe conditions. Hence, inspired by epidermal tissue of mammalian skin, we propose a biomimetic organohydrogel (BM-gel) electrolyte with extreme temperature tolerance and long-term moisture lock-in property, which is synthesized in an ethylene glycol/water solvent system with a chemically elastomeric coating on the surface. The BM-gel electrolyte exhibits high ionic conductivity when containing different ions, such as Zn²⁺, Li⁺, H⁺, and Na⁺ ions. A rechargeable Zn-MnO<inf>2</inf> battery is constructed with the BM-gel electrolyte, which exhibits excellent electrochemical performance over the temperature range from −20°C to 80°C. The specific capacity retains over 70% and coulombic efficiencies approach ~100% in full temperature scale. Even after a prolonged storage of 30 days without package, 84.6% capacity is retained benefiting from the superior antidehydration property bestowed by the thin elastomer coating. Furthermore, another two types of energy storage devices were also fabricated with the novel hydrogel, demonstrating the universal feature of our strategy. Abstract: (Figure presented.).