Low-Temperature-Resistant Sodium-Metal Batteries Enabled by Amphiphilic Diluent-Enhanced Electrolyte Design

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Sodium metal batteries (SMBs) offer high capacity and cost-effectiveness for grid storage.
• Challenges include unstable interfaces and poor low-temperature performance, hindering practical application.

Purpose of the Study:

• To design a novel electrolyte for low-temperature SMBs.
• To improve sodium metal interface stability and ion transport.

Main Methods:

• Incorporated an amphiphilic diluent into the electrolyte.
• Investigated its effect on Na+ solvation and electrode-electrolyte interphases (EEIs).
• Tested Na||Al/C half cells and Na||sulfurized polyacrylonitrile full cells at various temperatures.

Main Results:

• Enhanced Na+ transport and promoted anion incorporation into solvation sheaths.
• Formed robust, anion-derived, inorganic-rich EEIs.
• Achieved high Coulombic efficiencies at 25°C (97.84%) and -20°C (93.85%) in half cells.
• Demonstrated stable cycling (93.4% capacity retention over 500 cycles) in full cells.
• Maintained stable low-temperature performance for 200 cycles at -20°C.

Conclusions:

• The amphiphilic diluent strategy effectively stabilizes sodium metal interfaces for low-temperature operation.
• This approach enables durable, low-temperature-resistant sodium-sulfur batteries and other energy storage systems.