Lithium Diffusion-Efficient Ionogels as Polymer Solid Electrolyte for Next-Gen Lithium-Ion Batteries

Abstract

The search for safer next-generation lithium-ion batteries (LIBs) has driven significant research on non-toxic, non-flammable solid electrolytes. However, their electrochemical performance often falls short. This work presents a simple, one-step photopolymerization process for synthesizing biphasic liquid–solid ionogel electrolytes using acrylic acid monomer and P_111i4FSI ionic liquid. We investigated the impact of lithium salt concentration and temperature on ion diffusion, particularly lithium-ion (Li⁺) mobility, within these ionogels. Pulsed-field gradient nuclear magnetic resonance (PFG-NMR) revealed enhanced Li⁺ diffusion in the acrylic acid (AA)-based ionogels compared to their non-confined ionic liquid counterparts. Remarkably, Li⁺ diffusion remained favorable in the ionogels regardless of salt concentration. These AA-based ionogels demonstrate very good ionic conductivity (>1 mS cm⁻¹ at room temperature) and a wide electrochemical window (up to 5.3 V vs Li⁺/Li⁰). These findings suggest significant promise for AA-based ionogels as polymer solid electrolytes in future solid-state battery applications.