Electrochemical Performance of a Potassium‐Ion Complex Gel Electrolyte with Succinonitrile Embedded in an In Situ Constructed 3D Polymer Framework

Potassium-ion batteries (PIBs) represent an emerging energy storage technology, yet their widespread adoption is hindered by the inherent safety risks associated with conventional organic liquid electrolytes. To mitigate these challenges, a composite gel polymer electrolyte (SN@PPE-X) is synthesized by incorporating the plastic-crystal material succinonitrile (SN) into a rigid 3D confined polymer network. This is achieved through the in situ photopolymerization of pentaerythritol tetraacrylate (PETEA) after mixing SN with the monomer, forming a rigid framework that restricts SN mobility. The integration of SN enhances K⁺ dissociation from potassium salts, thereby elevating ionic concentration and improving ionic conductivity (1.30 × 10⁻³ S cm⁻¹) and transference number (0.72). Furthermore, the 3D polymer matrix confines SN, stabilizing the interface between SN@PPE-2 and potassium metal. When applied in PIBs, SN@PPE-2 demonstrates a capacity retention of 62% over 350 cycles at 50 mA g⁻¹, attributed to the rigid framework's ability to suppress cathode structural deformation, minimize parasitic reactions, and enhance rate performance. This gel electrolyte combines facile synthesis, cost-effectiveness, and scalability, underscoring its potential for industrial implementation.