Flame‐Retardant, Highly Conductive, and Low‐Temperature‐Resistant Organic Gel Electrolyte for High‐Performance All‐Solid Supercapacitors

Abstract

Traditional liquid electrolytes are volatile, flammable, and easy to leak, which makes the energy storage device easy to burn and explode in the case of overcharge and short circuit. Here, by utilizing the active PÀ H bond of a flame retardant (DOPO) to graft onto the polymer chain, flame-retardant organic gel electrolytes were fabricated to address these issues. The gel electrolyte had good ionic conductivity of 4 mS cm À 1 at 20°C and good flame retardant ability. By changing the molar ratio of the monomers and the salt concentrations, the mechanical strength of the gel electrolyte could be adjusted (maximum stress � 28 KPa, maximum strain � 305 %). The transport mecha-nism of lithium ions in the gel polymer electrolyte was proposed. The gel electrolyte-assembled supercapacitor (SC) possessed better electrochemical properties than that of SC assembled by liquid electrolyte. Importantly, the gel-based SC remained basically unchanged under multiple bending cycles. Additionally, the gel electrolyte had good low-temperature tolerance (0.1 mS cm À 1 at À 40°C). The gel electrolyte-assembled SC could work normally in the temperature range of À 20 to 60°C. The multiple advantages of gel electrolyte expand the applications in ionic conductor and energy storage devices.

Antifreezing Proton Zwitterionic Hydrogel Electrolyte via Ionic Hopping and Grotthuss Transport Mechanism toward Solid Supercapacitor Working at −50 °C

“…As an important part of energy storage devices, the freezing resistance of electrolytes directly affects the low-temperature performance of energy storage devices. Although a large number of studies are reported DOI: 10.1002/advs.202201679 on non-aqueous electrolytes with low melting point, [1][2][3][4][5] such as liquefied gas, [2] fluorinated solvent, [3] and ethyl acetate, [4] these non-aqueous electrolytes are usually costly, leaky, flammable and toxic, restricting their applications. In contrast, water-based electrolytes perform well in terms of low cost, non-flammability and non-toxicity, etc.…”

Anionic organo-hydrogel electrolyte with enhanced ionic conductivity and balanced mechanical properties for flexible supercapacitors

“…4g). 52,53 Furthermore, Fig. 4h shows that the SC devices still have a specific capacitance retention of 87% even after 3000 bending cycles, and the image of the device after 3000 cycles revealed that no appreciable mechanical cracks could be observed in the organo-hydrogel electrolyte, which indicated the excellent mechanical stability of the gel after cycling deformation.…”

Engineering chitosan into a recyclable and flame-resistant gel electrolyte via a dual cross-linking strategy for flexible supercapacitors

“…The substitution of traditional flammable organic solvents to non-flammable ionic liquids (ILs) in GPEs (termed ionogels) could significantly increase their fire retardance. [9][10][11] The incorporation of ILs in a poly(ionic liquids) network resulted in the formation of an ionogel electrolyte with high ionic conductivity (2.5 mS cm −1 ) and desirable mechanical properties (2.5 MPa), and it also could maintain its original size even at 150 °C and hardly be ignited by a flame. 12 Compared with polymer ionogels, hydrogel electrolytes are cheaper and intrinsically enhance the flame resistance and delay the combustion of the device, but it is still difficult to achieve absolute flame resistance.…”