BaTiO3 Nanoparticle-Induced Interfacial Electric Field Optimization in Chloride Solid Electrolytes for 4.8 V All-Solid-State Lithium Batteries

• Time-efficient ball milling achieves uniform BaTiO3 (BTO) coating without sacrificing ionic conductivity (1.06 mS cm−1). • Ferroelectric BTO coating suppresses Li2.5Y0.5Zr0.5Cl6 (LYZC) decomposition at 4.8 V via electric field modulation, enabling 76% capacity retention after 150 cycles. • BTO effectively minimizes the formation of interfacial ZrCl3O/YCl2O by-products and mitigates the irreversible phase transition of single-crystal NCM811 (SCNCM811), thereby improving the compatibility between LYZC and SCNCM811. • The electric field modulation strategy offers a promising route toward commercialization of high-voltage solid-state electrolytes and energy-dense all-solid-state batteries.