A solid dual-salt plastic crystal electrolyte enabling rapid ion transfer and stable interphases for high-performance...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Solid-state sodium ion batteries (SIBs) are promising energy storage systems.
• Key challenges include low ionic conductivity and poor interfacial compatibility in solid electrolytes.
• Developing stable and conductive solid electrolytes is crucial for advancing SIB technology.

Purpose of the Study:

• To develop a novel solid dual-salt plastic crystal electrolyte (PCE) for high-performance SIBs.
• To enhance ionic conductivity and interfacial stability in solid-state electrolytes.
• To enable stable operation of SIBs with high-voltage cathodes and efficient anodes.

Main Methods:

• Fabrication of a solid PCE using succinonitrile (SN), fluoroethylene carbonate (FEC), NaClO4, and NaBF4.
• Investigation of synergistic redox reactions between FEC and BF4- to form a protective interphase.
• Characterization of electrolyte properties including ionic conductivity, voltage tolerance, and interfacial compatibility.
• Electrochemical testing of SIBs with various cathode (Na3V4(PO4)3, Prussian white, Na3V2(PO4)2F3) and anode (hard carbon) materials.

Main Results:

• The developed dual-salt PCE exhibits an ionic conductivity of 3.79 mS cm-1.
• A robust, F- and B-rich interphase is formed, enhancing interfacial stability and enabling high-voltage tolerance (≥4.75 V).
• SIBs utilizing the PCE demonstrate exceptional cycling stability (>2500 cycles), high specific capacity (163.9 mAh g-1), and excellent rate performance (up to 60C).
• A full cell (hard carbon‖Na3V4(PO4)3) maintained stable cycling at 10C for over 100 cycles.

Conclusions:

• The solid dual-salt PCE effectively addresses the limitations of low ionic conductivity and poor interfacial compatibility in SIBs.
• The synergistic effects of the electrolyte components lead to enhanced electrochemical performance and stability.
• This work highlights the potential of the developed PCE for practical, high-performance solid-state sodium ion battery applications.