A Highly Conductive Gel Polymer Electrolyte for Li–Mg Hybrid Batteries

Abstract

Compared to lithium-ion batteries, lithium–magnesium hybrid batteries (LMIBs) provide high capacity and increased safety at a lower cost. However, their development has been hamstrung by a dependence on toxic and corrosive liquid electrolytes. To remove this roadblock, we fabricated a hybrid gel polymer electrolyte (hGPE) composed of lithium bis­(trifluoromethylsulfonyl)­imide (LiTFSI) and magnesium bis­(trifluoromethylsulfonyl)­imide [Mg­(TFSI)2] salts, 1-ethyl-3-methylimidazolium bis­(trifluoromethylsulfonyl)­imide ionic liquid (IL), and poly­(vinylidene fluoride-co-hexafluoropropylene), with an ionic conductivity of 3.2 mS/cm and excellent electrochemical stability. Ion dynamics within the hGPE were evaluated by dielectric analysis: ion transport within the hGPE is found to differ fundamentally from that of bulk IL solutions. We propose that the confinement of the IL within the polymer matrix induces aggregation at the pore center, leaving a pathway of high mobility at the pore edge. We then demonstrate the first proof-of-concept quasi-solid-state LMIB, with a high initial capacity of 141.5 mAh/g and Coulombic efficiencies above 90%.

Hybrid polymer gels for energy applications

“…The Li–Mg hybrid battery (LMIBs) exhibited high capacity and increased safety but their development was constrained for using toxic and corrosive liquid electrolytes. To eliminate this roadblock, Herzog-Arbeitman et al 139 produced an HPGE with the P(VDF- co -HFP) polymer matrix, swelled in 1-ethyl-2-methyl imidazolium bis(trifluoromethyl sulfonyl) imide (EMITFSI) ionic liquid (IL) solution having both lithium bis(trifluoromethyl sulfonyl)-imide (LiTFSI) and Mg(TFSI) 2 salts, producing a flexible conductive film. They fabricated a quasi-solid-state Li–Mg battery, using a LiFePO 4 (LFP) cathode, Mg anode, and HPGE electrolyte.…”

Novel Electrospun Sn-Based Composite Cathodes Exhibiting Extended Cycle Life for Hybrid Magnesium–Lithium Batteries

“…However, MLIBs currently confront substantial challenges during charge–discharge cycling due to the magnesium ion’s large ionic radius, sluggish diffusion kinetics, severe structural deformation, unsatisfactory specific capacity, and poor cycle life. − The crux of overcoming these obstacles lies in the discovery and design of cathode materials with exceptional electrochemical attributes. SnO 2 has been identified as a potential candidate for MLIB cathodes because of its high theoretical specific capacity, facile synthesis process, and economic viability .…”