Gel polymer electrolytes based on lignin for potassium batteries

Potassium batteries are novel candidates for post-lithium energy storage devices. Therefore, the devel-opment of polymer electrolytes derived from renewable resources is a significant step forward. A lignin-based membrane is developed by crosslinking a pre-oxidized Kraft lignin matrix with a diglycidyl (di-epoxy) oligomer, resulting in self-standing membranes capable of incorporating dissolved potassium salts. At room temperature when potassium metal cells were fabricated, the electrochemical characteriza-tions reveal a wide stability window (up to 4 V) and an ionic conductivity surpassing 10–3 S cm–1.The lignin-based electrolyte attained an initial specific capacity of 168 mAh g–1 at 0.05 A g–1 and outstanding operation for more than 200 cycles, which is an unprecedented result for biobased systems in the potas-sium batteries area.