Novel sulfur-based electrolyte additive for constructing high-quality sulfur-containing electrode-electrolyte interphase films in sodium-ion batteries

Sodium-ion batteries (SIBs) have been considered as the most promising grid-scale energy storage devices following lithium-ion batteries (LIBs). Similar to LIBs, the electrode–electrolyte interphase significantly impacts the cycling performance of the battery, and the presence of high-quality interphase films can greatly enhance the cycling performance of SIBs. In response to the interphase film challenges for SIBs, the investigation proposes the use of the sulfur-based additive 1,3-propanediol cyclic sulfate (PCS) to construct high-quality interphase films for improving electrochemical performance. Density functional theory (DFT) calculations indicate that PCS can preferentially undergo reduction–oxidation (Redox) reactions in conventional ester-based electrolyte systems, thereby forming sulfur-rich high-quality interphase films. This results in an increase in the capacity retention of NaNi1/3Fe1/3Mn1/3O2 (NFM)||hard carbon (HC) pouch cells from 33.94 % to 77.56 % after 300 cycles of long-term cycling. Although the addition of PCS slightly reduces the ionic conductivity of the electrolyte (7.70 mS cm−1 vs. 8.09 mS cm−1), it lowers the activation energy (1.09 eV vs. 1.20 eV) and increases the Na+ transfer number (0.721 vs. 0.707) of the electrolyte, thereby improving the rate capability of NFM||HC pouch cells. This study demonstrates the potential application of PCS in SIBs and presents a forward-looking approach for exploring the film formation mechanism of sulfur-based additives.