Prussian Blue-Type Sodium-ion Conducting Solid Electrolytes for All Solid-State Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Conventional solid electrolytes face limitations like H₂S gas evolution and high costs.
• Existing sulphide, oxide, and halide electrolytes have issues with gas evolution, cost, and poor contact.

Purpose of the Study:

• To introduce Prussian Blue analogue (PBA) open-framework structures as novel solid electrolytes.
• To investigate the relationship between Na⁺ conductivity and PBA lattice parameters.
• To explore the potential of PBAs for all-solid-state batteries.

Main Methods:

• Synthesis and characterization of five PBA materials.
• Measurement of Na⁺ conductivity.
• Analysis using relaxation time distribution and density functional theory (DFT) calculations.
• Feasibility testing including cycling performance.

Main Results:

• PBAs exhibit appreciable Na⁺ conductivity (>10⁻² mS cm⁻¹).
• Mn-PBA achieved the highest Na⁺ conductivity of 9.1×10⁻² mS cm⁻¹.
• Mn-PBA showed excellent cycle retention (95.1% after 80 cycles) at 0.2C.

Conclusions:

• PBA open-frameworks are viable solid electrolytes for all-solid-state batteries.
• Tuning lattice parameters influences Na⁺ conductivity by altering ion-framework interactions.
• Mn-PBA presents a promising candidate for next-generation solid-state batteries.