An oxygen-defective framework with intensified Lewis acidity reinforcing composite electrolyte for all-solid-state lithium metal batteries

Abstract

Composite solid electrolytes (CSEs) are considered a key component of all-solid-state lithium metal batteries, regarded as the next generation of energy storage devices with high energy density and long operating life. Numerous studies have shown that the performance of CSEs is closely related to the structure of the fillers and the interactions between fillers and other components, including polymer matrices and lithium salts. To create more abundant interaction sites in CSEs, we designed a nanostructured framework with intensified Lewis acidity (PVDF-HFP/Ov-CeO₂) for poly(ethylene) oxide (PEO) electrolyte (denoted as Ov-CeO₂-CSE). The mystery concerning the nanostructured framework adsorbs with PEO polymer and dissociates TFSI⁻ and its influence on the electrochemical lithium ions storage performance is meticulously revealed by coupling experimental with theoretical results. Impressively, the prepared Ov-CeO₂-CSE shows improved ionic conductivity (1.76 × 10⁻⁴ S cm⁻¹ at 30 °C) and a good lithium-ion transference number (0.49). The Li||Ov-CeO₂-CSE||Li cell exhibits great cyclability over 3500 h at a current density of 0.1 mA cm⁻² (areal capacity: 0.1 mAh cm⁻², 60 °C). Furthermore, the Li||Ov-CeO₂-CSE||LFP cell delivers a high specific capacity of 154.6 mAh g⁻¹ at a current density of 0.5 C, stably maintained over 500 cycles. This work provides a potential strategy for designing multifunctional frameworks by efficient interfaces to build advanced all-solid-state lithium metal batteries.