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

This study proposes an interface modification strategy coupling F-doping with the in situ construction of a LiF buffer layer. Theoretical calculations reveal the potential mechanism by which F-doping enhances ionic transport kinetics in LATP. The synergy between F-doping and the interface layer significantly increases the proportion of Li migration through the solid phase in the hybrid solid-liquid system, effectively suppressing Li-ions concentration polarization within the system and resulting in excellent electrochemical performance and cycling stability. 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 1.3 Al 0.3 Ti 1.7 P 3 O 12 (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 LiFePO 4 and LiNi 0.8 Co 0.1 Mn 0.1 O 2 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.