A comparative study on the impact of different glymes and their derivatives as electrolyte solvents for graphite co-intercalation electrodes in lithium-ion and sodium-ion batteries

摘要: The abundance of sodium has recently sparked considerable interest in sodium-ion batteries (NIBs). Their similarity to conventional lithium-ion technology is obvious; however, the cell chemistry often significantly deviates. Graphite, although being standard negative electrode Li-ion batteries, largely inactive for Na-ion storage non-aqueous carbonate-based electrolytes, example. Very recently, it been demonstrated that graphite can be activated cells with ether-based electrolytes. mechanism based on co-intercalation solvent molecules along Na-ions, forming ternary intercalation compounds (t-GICs). This process highly reversible but yet poorly understood. Here, we provide a comprehensive study formation and stability t-GICs. A series ether solvents are discussed: linear glymes different chain lengths (mono-, di-, tri-, tetraglyme), several derivatives side groups as well tetrahydrofuran (THF) cyclic one crown ether. We show redox potentials shift depending length mixing ethers might enable tailoring behaviour. inferior behaviour triglyme likely due less ideal ion coordination. Complementary experiments lithium made demonstrate superior sodium. find increase graphene layer spacing during only slightly depends range 250%, still mechanical preserved. further t-GICs possess chemical kinetically favoured charge transfer probably absence solid electrolyte interphase.