Novel dopamine-containing gel polymer electrolytes for Li-organic batteries

We present a new gel polymer electrolyte (GPE) based on a dopamine-containing comonomer for lithium-organic battery cells. First, several liquid electrolyte solutions composed of an ionic liquid and a lithium salt were prepared and tested in Li-organic cells with poly(2,2,6,6-tetramethyl-1-piperidinyloxy-4-yl methacrylate) (PTMA) as the positive electrode active material to evaluate the compatibility. Among them, ionic liquid electrolyte (ILE) (1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIMFSI):lithium bis(fluorosulfonyl)imide (LiFSI), 0.8:0.2, mol:mol) was found to lead to the highest specific capacity (63.5 mAh g⁻¹ at 1C). The polymer matrix composed of benzyl methacrylate (BnMA), poly(ethylene glycol) methyl ether methacrylate (mPEGMA), and dopamine methacrylamide (DMAAm) was synthesized by UV-polymerization. A literature-known polymer system without DMAAm was prepared for comparison. Samples from both polymer films were immersed in the ILE to obtain GPEs. It was found that the addition of DMAAm increased the electrolyte uptake significantly. GPEs comprising DMAAm reveal high ionic conductivity (2.3 mS cm⁻¹ at 20 °C) and improved galvanostatic cycling performance in Li//PTMA cells compared to the GPEs without DMAAm.