Enhancing Sodium‐Ion Battery Performance: The Role of Glyoxylic Acetal‐Based Electrolytes in Solid Electrolyte Interphase Formation and Stability

This study systematically investigates the feasibility of replacing
conventional sodium hexafluorophosphate (NaPF 6 ) in carbonate-
based electrolytes with sodium bis(fluorosulfonyl)imide (NaFSI)
and sodium bis(trifluoromethanesulfonyl)imide (NaTFSI) in a
1,1,2,2-tetraethoxyglyoxal (TEG):propylene carbonate (PC) solvent
system tested with hard carbon (HC) anode materials for sodium-
ion batteries (SIBs). The influence of electrolyte composition and
cycling conditions on the evolution of the solid electrolyte inter-
phase (SEI) and overall electrochemical performance of the HC is
comprehensively evaluated by means of electrochemical imped-
ance spectroscopy and X-ray photoelectron spectroscopy.
The SEI chemical composition, transport properties, and stability
are thoroughly characterized. The results demonstrate that the
HC tested in NaFSI/TEG:PC electrolyte exhibits superior performance
compared to both the conventional NaPF6/ethylene carbonate (EC):
PC system and the NaTFSI/TEG:PC-based alternative, achieving
higher initial coulombic efficiencies (ICEs), lower interfacial resis-
tance, and enhanced Na þ transport properties. ... mehrThe improved
electrochemical stability of the HC in NaFSI/TEG:PC electrolyte
is attributed to the formation of a bilayered SEI, comprising an
inorganic-rich inner layer and an organic-rich outer layer. These
findings underscore the pivotal role of electrolyte formulation
in enhancing the HC SEI characteristics and cycling performance,
thereby positioning NaFSI in TEG:PC chemistry as a promising
electrolyte candidate for next-generation SIBs