Porous Poly(PolyEthylene Glycol Methyl Ether Methacrylate) Gel Polymer Electrolyte With Superior Electrochemical Properties in a High‐Performance Potassium‐Ion Battery

ABSTRACT Potassium‐ion batteries as a suitable alternative to lithium‐ion batteries have drawn attention due to available sources of potassium, low reduction potential, better diffusion through electrolyte/electrode interface, and good ionic conductivity. Here, a photopolymerized porous gel polymer electrolyte based on poly(polyethylene glycol methyl ether methacrylate) and poly(methyl methacrylate) nanoparticles shows superior thermal and electrochemical properties. After swelling in a KPF 6 and EC/PC solution, the best GPE demonstrates high ionic conductivity of 2.9 × 10 −2 S cm −1 , potassium transference number of 0.88, and high electrochemical stability of > 6 V. This excellent electrochemical property could be related to high solvent uptake, high surface area, K + pathway channels, low T g , and the electron donor groups of the porous poly(polyethylene glycol methyl ether methacrylate). Also, this GPE shows an initial capacity of 155 mAh g −1 , an initial Coulombic efficiency of ~100%, and capacity retention of 99.9% after 100 cycles in a high current density of 5 C with high‐voltage FeFe(CN) 6 as the cathode and graphite as the anode. FE‐SEM images show the ability to suppress dendrites after 100 cycles of charge–discharge at 5 C. Additionally, this GPE demonstrates 143 mAh g −1 capacity at a very high C‐rate of 10, showing its ability for use in high‐performing rechargeable potassium batteries.