Low-temperature and high-rate sodium metal batteries enabled by electrolyte chemistry

High-rate cycling of alkali metal batteries at subzero temperature is essential for their practical applications in extreme environments. Here, we realize high-rate low-temperature sodium metal batteries (LT SMBs) through modulating electrolyte chemistry. By introducing a weak Na+ solvating co-solvent, tetrahydrofuran/1,2-Dimethoxyethane (THF/DME), the kinetic barrier for Na+ desolvation is significantly mitigated. Furthermore, an anion-derived NaF-rich solid-electrolyte interphase (SEI) film generated on the sodium electrode suppresses the dendrite growth and guarantees stable cycling of SMBs down to -60 degrees C. In consequence, the symmetric Na/Na batteries achieve a high current density of 3 mA cmxe213; 2 at -20 degrees C and 2 mA cmxe213; 2 at -40 degrees C. Meanwhile, they exhibit an outstanding cumulative cycling capacity of 1350 mAh cmxe213; 2 (-20 degrees C) and 285.5 mAh cmxe213; 2 (-40 degrees C), which outperforms the previously reported LT alkali metal symmetric batteries. Moreover, the Na-NaTi2(PO4)3 (NTP) full batteries exhibit a power density of 1396.5 W kgxe213; 1 at 46.2 Wh kgxe213; 1 (based on NTP) under -40 degrees C.

Automated summary

High-rate low-temperature sodium metal batteries (LT SMBs) were achieved through modulating electrolyte chemistry. The introduction of a weak Na+ solvating co-solvent and the formation of an anion-derived NaF-rich solid-electrolyte interphase (SEI) film effectively reduced the kinetic barrier for Na+ desolvation and suppressed dendrite growth on the sodium electrode. This method enables stable cycling and high current density of sodium metal batteries under extreme low-temperature conditions.