Room-Temperature Flexible Quasi-Solid-State Rechargeable Na-O₂ Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Rechargeable sodium-oxygen (Na-O₂) batteries offer high energy density but face challenges with liquid electrolytes.
• Issues include dendrite growth, electrolyte leakage, and water contamination affecting the sodium (Na) metal anode.

Purpose of the Study:

• To develop a high-performance quasi-solid-state polymer electrolyte (QPE) for rechargeable Na-O₂ batteries.
• To address the limitations of conventional liquid electrolytes in Na-O₂ systems.

Main Methods:

• Fabrication of a QPE using poly(vinylidene fluoride-co-hexafluoropropylene), SiO₂, NaClO₄, and tetraethylene glycol dimethyl ether.
• Utilized Density Functional Theory (DFT) and Finite Element Method (FEM) simulations.
• Electrochemical testing of fabricated quasi-solid-state Na-O₂ batteries.

Main Results:

• QPE exhibited high ionic conductivity (1.0 mS cm^-1) due to beneficial Na⁺ transfer facilitated by fluorocarbon chains.
• FEM simulations indicated uniform electric field distribution, leading to homogeneous Na deposition without dendrites.
• The QPE protected the Na anode from water erosion, achieving 97% average Coulombic efficiency and stable cycling over 80 cycles.

Conclusions:

• The developed QPE enables high-performance rechargeable Na-O₂ batteries with enhanced safety and stability.
• Demonstrated the potential for flexible pouch-type Na-O₂ batteries with stable electrochemical performance under bending stress.