Sodiophilic Substrate Induces NaF-Rich Solid Electrolyte Interface for Dendrite-Free Sodium Metal Anode

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium metal batteries offer high energy density but face challenges with dendrite formation and electrode instability.
• High surface area 3D substrates can exacerbate side reactions, limiting performance, especially at high current densities.

Purpose of the Study:

• To develop a stable sodium metal anode by regulating the solid electrolyte interface (SEI) and suppressing detrimental side reactions.
• To enhance the performance and cycling stability of sodium batteries using a novel 3D substrate.

Main Methods:

• Uniformly loading sodium-tin (Na-Sn) alloy onto a porous 3D nanofiber framework (NaSn-PCNF).
• Investigating the interaction between Na-Sn alloy and PF₆^- anions to understand ion dissociation and charge transfer.
• Analyzing the modulation of interfacial electrolyte solvation structure and SEI layer composition (high NaF content).

Main Results:

• NaSn-PCNF demonstrates stable cycling for over 600 hours with a low overpotential (24.5 mV) at 10 mA cm^-2 and 10 mAh cm^-2.
• The Na-Sn alloy interaction promotes sodium salt dissociation and free ion availability.
• The modified interface and SEI layer enhance electrode stability and reversibility.

Conclusions:

• The NaSn-PCNF strategy effectively stabilizes the sodium metal anode by controlling interfacial reactions.
• This approach accelerates reaction kinetics and improves capacity retention in sodium batteries.
• The findings provide valuable insights for designing advanced sodium substrates for high-energy sodium metal batteries.