Sandwiched composite electrolyte with excellent interfacial contact for high-performance solid-state sodium-ion...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-state Chemistry

Background:

• Solid-state sodium-ion batteries (SSIBs) offer high safety and energy density but suffer from low ionic conductivity and poor interfacial contact.
• Developing advanced solid-state electrolytes (SSEs) is crucial for overcoming these limitations and enabling practical SIB applications.

Purpose of the Study:

• To design and synthesize a novel composite SSE based on PVDF-HFP and Ce4+/F- co-doped Na3Zr2Si2PO12 (NZC0.05SPF0.7).
• To investigate the effects of Ce4+ and F- doping on the structural and electrochemical properties of the SSE.
• To evaluate the performance of the composite SSE in a solid-state sodium-ion battery.

Main Methods:

• Co-doping of Na3Zr2Si2PO12 with Ce4+ and F- to create NZC0.05SPF0.7.
• Fabrication of a sandwiched composite SSE (G-NZC0.05SPF0.7-G) using PVDF-HFP membranes.
• Characterization of crystal structure, density, and ionic conductivity.
• Electrochemical testing, including ionic conductivity measurements, electrochemical stability window, critical current density, and cycling performance in a full battery.

Main Results:

• The optimal NZC0.05SPF0.7 exhibited high ionic conductivity (1.39 × 10^-3 S cm^-1 at 25 °C).
• The PVDF-HFP membrane enhanced interfacial compatibility between the electrolyte and electrodes.
• The G-NZC0.05SPF0.7-G SSE demonstrated excellent performance: ionic conductivity of 1.07 × 10^-3 S cm^-1 at 25 °C, a wide electrochemical stability window (4.5 V), high critical current density (1.2 A cm^-2), and stable Na plating/stripping over 600 h.
• The assembled SIB showed remarkable cycling stability and rate capability.

Conclusions:

• Ce4+/F- co-doping is an effective strategy to enhance the ionic conductivity of Na3Zr2Si2PO12.
• The PVDF-HFP/NZC0.05SPF0.7/PVDF-HFP composite SSE exhibits superior properties for solid-state sodium-ion batteries.
• This work presents a promising approach for developing advanced SSEs for high-performance and safe energy storage devices.