ИСТИНА

In recent years, extensive attention has been paid to developing sodium-ion batteries as competitors to lithium-ion counterparts in large-scale energy storage systems. One of promising version of such batteries is a battery with two-phase electrode, e.g. with positive electrode based on sodium vanadium phosphate (Na3V2(PO4)3, NVP ) and negative one based on sodium titanate (Na2Ti3O7, NTO). The objectives of present work are studies of behavior of these electrodes and full cell at negative temperatures. It is worth noting that literature data on temperature effects upon sodium insertion into functional materials are few and far between (see [1]). The electrodes under study were made from composites of the active materials with carbon ((Na3V2(PO4)3@C and (Na2Ti3O7@C)). 1M LiClO4 in ethylene carbonate‒propylene carbonate mixture was used as an electrolyte. Melting point of this electrolyte is as low as ‒80 oC. The electrodes based on (Na3V2(PO4)3@C were found to be efficient up to ‒45 oC, whereas the efficiency of (Na2Ti3O7@C) was limited at ‒35 oC.The behavior of full cell is determined by performance of negative electrode in this case.