Construction of Polyvinylidene Fluoride Buffer Layers for Li1.3Al0.3Ti1.7(PO4)3 Solid-State Electrolytes toward Stable Dendrite-Free Lithium Metal Batteries

The NASICON-type inorganic electrolyte Li1.3Al0.3Ti1.7(PO4)3 (LATP) is an ideal solid electrolyte material for solid-state batteries due to its remarkable lithium-ion conductivity, wide electrochemical window, and superb environmental stability. However, its poor contact with electrodes and incompatibility with lithium (Li) anodes cause high interfacial impedance or even electrolyte deactivation. To address these issues, a double-side-modified LATP ceramic pellet with a flexible polyvinylidene fluoride (PVDF) polymer electrolyte capable of promoting LATP/electrode interfacial contact and synchronously modifying LATP/Li interfacial compatibility is constructed. The results demonstrate that the introduction of the PVDF buffer layers effectively reduces the interface impedance (5789 Ω → 271 Ω), prevents the occurrence of unwanted reactions of Li anode and LATP, and thus ensures the stable operation of the battery. The Li/Li cell fabricated by PVDF-modified LATP ceramic pellet exhibits over 3000 h of stable dendrite-free cycling at 0.1 mA cm–2 and small polarization (30 mV). This solid-state LiFePO4/Li battery exhibits a capacity retention of 83.4% after 300 cycles, implying its good cycling stability. This study indicates that such an interfacial modification strategy is effective for anodic protection and contributes to the formation of stable solid-state batteries.