Multi-Group Functional Additive Enhances the Wide-Temperature-Range Performance of Sodium-Ion Batteries

A functional electrolyte with trimethylsiloxybenzenesulfonate (TMBS) multigroup additive is developed to enhance the performance of NaNi 0.33 Fe 0.33 Mn 0.33 O 2 (NFM)/hard carbon (HC) sodium-ion batteries (SIBs) from 60 to −30 °C. Compared to the additive-free baseline electrolyte or the electrolytes containing monofunctional methylmethanesulfonate (MS) and methylbenzenesulfonate (MBS) additives, TMBS is more conducive to suppress the excessive side reactions at the anode and promoting the formation of robust cathode-electrolyte interphase (CEI) over a wide temperature range. TMBS-containing cells exhibit enhanced performance in overdischarge testing at 60 °C, rate capability and cycling stability at 45 °C, discharge performance at −30 °C, as well as low-temperature cycling stability at −10 °C. Besides, this work provides an effective additive design principle for pouch NFM/HC SIBs.