Interfacial weak interaction bridges in PVDF-HFP electrolytes via nano-ZrP enable fast charging of solid-state lithium batteries

Abstract

Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based polymer electrolytes have garnered significant interest for solid-state lithium metal batteries (SSLMBs) owing to their high ionic conductivity, robust mechanical strength, and superior thermal stability. However, undesired phase separation within the polymer matrix during film formation impedes rapid ion migration. To address this, a cost-effective zirconium phosphate (ZrP) filler featuring a two-dimensional layered architecture is incorporated into the PVDF-HFP matrix. The 2D ZrP nanosheets not only modulate polymer particle size and bridge adjacent spherulitic domains to construct continuous ion transport channels, but also leverage their abundant surface chemistry, namely strong DMF adsorption and –OH⋯TFSI− interactions, to reconfigure the Li+ solvation sheath and attenuate the Li+–TFSI− coulombic attraction. This synergistic combination of topological and chemical functionality accelerates ion migration, as evidenced by a high ionic conductivity of 1.4 × 10−3 S cm−1. Furthermore, a compact LiF-rich interphase is formed on both the anode and the cathode, effectively suppressing interfacial side reactions during high-rate cycling. Consequently, benefiting from these synergistic effects, Li‖Li symmetric cells demonstrate stable cycling at 0.3 mA cm−2, and Li‖LiFePO4 full cells deliver a high capacity of ∼96.7 mAh g−1 even after over 700 cycles at 5C. This work presents a promising filler-mediated strategy to accelerate ion migration for high-performance SSLMBs.