Ultra-stable solid-state lithium metal batteries with ferroelectric oxide-enhanced PVDF-based hybrid solid electrolytes

Abstract

Polymer electrolytes are promising for solid-state lithium metal batteries, while intrinsic limitations such as low room-temperature ion conductivity and moderate electrochemical stability exist. The introduction of inorganic particles provides limited improvement in ionic conductivity and fails to alleviate dendrite formation, which severely compromises battery stability. Herein, we present a highly conductive hybrid solid electrolyte (HSE) composed of polyvinylidene fluoride (PVDF), Ga/Nb-doped Li_6.4Ga_0.2La₃Zr_1.6Nb_0.4O₁₂ as the active filler, and ferroelectric BaTiO₃ as the functional filler, referred to as PLBO. Under electric bias, BTO particles generate reverse electric fields to dissociate Li salts to boost ion migration. Also, BTO with a high dielectric constant equalizes the potential difference at the electrolyte–electrode interface for homogeneous Li deposition. As a result, the hybrid electrolyte exhibits a high lithium transference number (t_Li⁺ = 0.413) and ionic conductivity of 0.74 mS cm⁻¹ at a temperature of 25 °C. Additionally, both the electrochemical and the cycling performance of Li//Li symmetric, LiFePO₄ (LFP)‖Li and LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811)‖Li batteries could be significantly improved when PLBO electrolytes are utilized. Our work validates the potential of ferroelectric materials in hybrid solid electrolytes to alleviate dendrite formation and enhance the performance of all-solid-state lithium batteries.