02655nas a2200277   4500008004100000022001400041245013400055210006900189260000800258490000600266520167900272653002101951653003901972653001402011653002602025653002402051100001702075700002102092700001602113700003602129700001902165700002302184700002102207700001902228856013002247       2025                        eng d  a2366-960800aInsights into electrolyte-solvent interactions and SEI formation for sustainable sodium-ion battery operation at low temperatures0 aInsights into electrolytesolvent interactions and SEI formation   cSEP0 v93 a<p>
	Sodium-ion batteries (SIBs) show promise as an alternative to lithium-ion batteries. However, they face performance challenges at ultra-low temperatures (&lt;-40 degrees C) due to slow Na+ transfer kinetics with conventional electrolytes. This limitation restricts their use in extreme environments such as polar regions and outer space. The presented systematic study addresses this challenge by modulating and tailoring the electrolyte composition for SIBs, enabling ultra-low temperature operation down to -110 degrees C for the first time. The comprehensive molecular dynamic and density functional theory calculations combined with experimental Raman spectroscopy and nuclear magnetic resonance studies of advanced electrolytes provided a deeper mechanistic understanding of the solvation structures and their impact on electrochemical performance. By varying the solvent composition with a combination of tetrahydrofuran and 2-Methyltetrahydrofuran solvents and sodium hexafluorophosphate (NaPF6) salt, the freezing point, solubility, and Na+ solvation structure of the electrolyte is modulated and studied in detail. The extensive anion engagement in the optimized mix solvent electrolyte facilitated the formation of a stable and inorganic-rich solid electrolyte interphase layer, ensuring low overpotentials and uniform Na+ deposition, yielding superior cycling stability. As a result, the developed electrolyte enables SIBs to achieve reversible capacities of 88 mAh g(-1) at -60 degrees C and 50 mAh g(-1) at -100 degrees C. These insights may contribute to developing improved energy storage devices suitable for challenging environmental conditions.</p>
10acontact-ion pair10asolid electrolyte interphase (SEI)10asolvation10aultra-low temperature10aXPS-depth Profiling1 aKim, Soohwan1 aMirzapure, Vinay1 aAtwi, Rasha1 aKoppisetti, Heramba, V. S. R. M1 aWasnik, Kundan1 aRajput, Nav, Nidhi1 aShelke, Manjusha1 aPol, Vilas, G.  uhttps://library.ncl.res.in/content/insights-electrolyte-solvent-interactions-and-sei-formation-sustainable-sodium-ion-battery