A facile construction of LiF interlayer and F-doping via PECVD for LATP-based hybrid electrolytes: Enhanced Li-ion transport kinetics and superior lithium metal compatibility

Hybrid solid-liquid electrolytes show promise in resolving interfacial side reactions and poor electrode|electrolyte contact of solid-state batteries. However, the energy barrier between the liquid and the solid-state electrolytes impedes Li-ion migration, reducing Li⁺ transport efficiency and overall battery performance. Here, we propose a modification strategy using plasma-enhanced chemical vapor deposition (PECVD) technology with fluoroethylene carbonate as the fluorine source, enabling in situ construction of a LiF buffer layer and F-doping on the Li_1.3Al_0.3Ti_1.7P₃O₁₂ (LATP) skeleton. Computational analyses reveal that F-doping activates additional Li-ion migration pathways, enhances ionic conductivity, and suppresses Li dendrite growth. The LiF layer prevents electron penetration and direct contact between LATP and Li metal, while also reducing the desolvation energy barrier to improve Li-ion transport across the solid|liquid interface with aids of F-doping. Consequently, Li||Li cells demonstrate stable cycling for 9000 h at 0.1 mA cm^–2 and a critical current density of 2.2 mA cm^–2. Furthermore, full cells paired with LiFePO₄ and LiNi_0.8Co_0.1Mn_0.1O₂ cathodes retain 81.3 % and 67.2 % of their initial capacity after 300 cycles at 0.5 C. This study highlights the potential of PECVD technology for optimizing the interfaces of solid-state electrolytes, offering new insights into advancing next generation lithium metal battery performance.