Grain Boundary Design of Solid Electrolyte Actualizing Stable All-Solid-State Sodium Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Advanced inorganic solid electrolytes (SEs) are crucial for developing safe, high-energy-density all-solid-state alkaline metal batteries.
• Interfacial stability remains a significant challenge for all-solid-state sodium metal batteries (ASSMBs).

Purpose of the Study:

• To design a new interphase to overcome interfacial stability issues in ASSMBs.
• To improve the performance and safety of ASSMBs through electrolyte modification.

Main Methods:

• Mg2+ doping of Na3Zr2Si2PO12 (NZSP) solid electrolyte to create a Na3-2δMgδPO4-dominant interphase.
• Characterization of interfacial resistance and electrochemical performance of the modified electrolyte.
• Assembly and testing of an all-solid-state NaCrO2//Na battery.

Main Results:

• The optimal NZSP-0.2Mg electrolyte exhibited a low interfacial resistance (93 Ω cm2), over 16 times lower than undoped NZSP.
• Exceptional Na plating/stripping stability was maintained for over 7000 hours at 0.3 mA cm-2.
• The assembled all-solid-state NaCrO2//Na battery showed a high capacity (110 mAh g-1 at 1C) with remarkable cycling stability (1755 cycles) and excellent rate capability (99.8% Coulombic efficiency at 5C).

Conclusions:

• The engineered interphase effectively suppresses sodium metal dendrite penetration and enhances interfacial contact.
• The Mg2+-doped solid electrolyte demonstrates record-high cycling stability for ASSMBs.
• This work signifies a promising advancement for solid-state electrochemical energy storage systems.