BaTiO₃ Nanoparticle-Induced Interfacial Electric Field Optimization in Chloride Solid Electrolytes for 4.8 V...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Chloride-based solid electrolytes are promising for high-energy-density all-solid-state batteries (ASSBs).
• Their low oxidative decomposition threshold (around 4.2 V) limits application in ultrahigh-voltage systems (e.g., 4.8 V).
• Parasitic interfacial reactions and electrolyte decomposition hinder ASSB performance.

Purpose of the Study:

• To enhance the oxidative stability and interfacial compatibility of chloride solid electrolytes for high-voltage ASSBs.
• To investigate the effect of ferroelectric BaTiO3 nanoparticle coatings on Li2.5Y0.5Zr0.5Cl6 (LYZC) electrolytes.
• To improve the cycling stability and energy density of ASSBs operating at 4.8 V.

Main Methods:

• Coating Li2.5Y0.5Zr0.5Cl6 (LYZC) electrolytes with ferroelectric BaTiO3 (BTO) nanoparticles (50-100 nm thick) via ball-milling.
• Characterizing interfacial ionic conduction and electrochemical stability using electrochemical impedance spectroscopy and cyclic voltammetry.
• Analyzing interfacial chemistry changes using time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS).
• Fabricating and testing ASSB cells with coated (LYZC@5BTO) and pristine LYZC electrolytes.

Main Results:

• LYZC@5BTO maintained high ionic conductivity (1.06 mS cm⁻¹).
• The BTO coating effectively mitigated voltage-induced decomposition and suppressed interfacial reactions with NCM811 cathodes.
• ASSB cells with LYZC@5BTO showed improved discharge capacity (95.4 mAh g⁻¹ over 200 cycles at 1 C) compared to pristine LYZC (55.4 mAh g⁻¹).
• Interfacial side reaction by-products (Metal-O-Cl) were significantly reduced in LYZC@5BTO (14% after 200 cycles) versus pristine LYZC (26% after 200 cycles).

Conclusions:

• Ferroelectric nanoparticle surface modification is an effective strategy to enhance the electrochemical stability of chloride solid electrolytes.
• This electric field modulation approach enables high-voltage operation of ASSBs by suppressing interfacial degradation.
• The developed LYZC@5BTO electrolytes show significant potential for commercializing high-energy-density, safe all-solid-state batteries.