Enabling low-temperature sodium metal batteries via a multifunctional electrolyte additive

Area of Science:

• Electrochemistry
• Materials Science
• Battery Technology

Background:

• Tetrahydrofuran (THF) is a promising low-temperature solvent for sodium metal batteries.
• Trace water in THF can initiate ring-opening polymerization, causing gelation, conductivity loss, and poor interfacial kinetics.

Purpose of the Study:

• To develop a method to inhibit THF polymerization in sodium metal batteries.
• To enhance the stability and performance of sodium metal batteries at low temperatures.

Main Methods:

• Introduction of tris(pentafluorophenyl)borane as a polymerization inhibitor.
• Electrochemical testing of sodium deposition/stripping.
• Cycling performance evaluation of Na3V2(PO4)3/Na full cells at -20 °C.

Main Results:

• Tris(pentafluorophenyl)borane effectively inhibited THF polymerization.
• Achieved stable sodium deposition/stripping at 2.0 mA cm⁻², for 1000 hours at -20 °C.
• Na3V2(PO4)3/Na full cell maintained 66.0 mAh g⁻¹ after 1000 cycles at 10.0 A g⁻¹ and -20 °C.

Conclusions:

• Tris(pentafluorophenyl)borane is an effective additive for stabilizing THF-based electrolytes in sodium metal batteries.
• The strategy significantly improves the low-temperature performance and cycling stability of sodium metal batteries.