A Nonflammable Deep Eutectic Electrolyte for Safe and High-Performance Lithium Iron Phosphate-Lithium Titanium Oxide Cells

High Resolution Image Download MS PowerPoint Slide Advancements in electrolyte design are crucial for mitigating the risks of thermal runaway and enhancing the overall safety of lithium-ion batteries (LIBs). In this context, we develop and evaluate a nonflammable deep eutectic electrolyte (1:3 LiTFSI:EC) with lithium tin oxide (LTO) and lithium iron phosphate (LFP) electrodes, which serves as a promising alternative to conventional flammable carbonate-based systems. The nonflammable electrolyte facilitates lithium-ion transport while preventing thermal runaway or flammability, enhancing cell safety. Electrochemical evaluations of half-cells and full LFP-LTO cells reveal quasi-reversible, diffusion-controlled conditions; high capacity retention (>85% over 400 cycles); low initial interfacial resistance; stable performance across current rates (C/20–4C); and robust energy efficiency (∼83% at 1C), despite the lower operating voltage (2.5 vs >4.0 V). Postcycling analyses confirm the structural stability, albeit with moderate degradation. While the initial cost of the discussed electrolyte may be higher, its improved safety, lifespan, and compatibility with LTO and LFP electrodes make it practically viable for power and stationary applications where reliability is essential.