In Situ Generation of a Robust Gel Polymer Electrolyte From a Poly(Ethylene Carbonate)‐Hydrogenated Nitrile Butadiene Rubber Containing Thermoplastic Vulcanizate Electrolyte

ABSTRACT

Conventional gel polymer electrolytes are produced by a combination of solution casting, polymer matrix infiltration, and subsequent polymerization. This process is time and resource intensive making it ill‐suited for large‐scale implementation. This work introduces gel polymer electrolyte thermoplastic vulcanizates (GPE–TPV) that are produced via dynamic crosslinking during melt‐extrusion. These electrolytes are comprised of a crosslinked hydrogenated nitrile butadiene rubber (HNBR) phase that is dispersed in poly(ethylene carbonate) (PEC). The thermal treatment of this solid–solid blend induces the decomposition of PEC to yield ethylene carbonate (EC) which is subsequently absorbed into the crosslinked HNBR. The melt‐extrusion process uses no added solvents making it fast and waste‐free. The in situ decomposition of PEC results in uniform EC distribution which is difficult to achieve with traditional solution or drop casting methods. The resultant GPE–TPV electrolytes are orders of magnitude more conductive than the initial PEC–HNBR solid polymer electrolyte. The crosslinked HNBR phase provided significant advantages over the non‐crosslinked GPE including higher mechanical strength and electrochemical stability, enabling cycling in LiFePO ₄ –Li half cells.