Interface-Compatible Gel-Polymer Electrolyte Enabled by NaF-Solubility-Regulation toward All-Climate Solid-State...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Gel-polymer electrolytes (GPEs) offer enhanced safety for sodium batteries but suffer from poor interfacial compatibility.
• Achieving simultaneous stable interfaces with both cathode and anode remains a significant challenge in GPE development.

Purpose of the Study:

• To develop a novel GPE with improved interfacial compatibility for high-safety sodium batteries.
• To investigate the electrochemical performance and interfacial behavior of a new PLA-NaF GPE.

Main Methods:

• Fabrication of salt-in-polymer fibers using electrospinning of polylactide (PLA) and sodium fluoride (NaF).
• In situ formation of the GPE within liquid electrolytes.
• Electrochemical characterization including ion conductivity, transference number, and cell performance testing.

Main Results:

• The PLA-NaF GPE exhibited high ion conductivity (2.50×10^-3 S cm^-1) and Na⁺ transference number (0.75) at room temperature.
• A concentrated electrolyte environment formed due to NaF dissolution, leading to stable inorganic-rich cathode-electrolyte interphase (CEI) and dendrite-free sodium anode.
• The GPE demonstrated excellent compatibility with various sodium battery cathodes (Na₃V₂(PO₄)₃, Na_2+2xFe_2-x(SO₄)₃, Na_0.72Ni_0.32Mn_0.68O₂, NaTi₂(PO₄)₃).

Conclusions:

• The developed PLA-NaF GPE effectively addresses interfacial compatibility issues in sodium batteries.
• The GPE enables dendrite-free sodium anodes and stable cathode interfaces, leading to superior electrochemical performance.
• This GPE shows promise for all-climate, high-safety sodium battery applications.