Multifunctional Protection Layers via a Self-Driven Chemical Reaction To Stabilize Lithium Metal Anodes

The Li metal anode is considered one of the most potential anodes due to its highest theoretical specific capacity and the lowest redox potential. However, the scalable preparation of safe Li anodes remains a challenge. In the present study, a LiF-rich protection layer has been developed using self-driven chemical reactions between the Li3xLa2/3-xTiO3/polyvinylidene fluoride/dimethylacetamide (LLTO/PVDF/DMAc) solution and the Li metal. After coating the LLTO/ PVDF/DMAc solution to Li foil, PVDF reacted with Li spontaneously to form LiF, and the accompanying Ti4+ ions (in LLTO) were reduced to Ti3+ to form a mixed ionic and electronic conductor LixLLTO. The protective layer can redistribute the Li-ion transport, regulate the even Li deposition, and inhibit the Li dendrite growth. When paired with LiFePO4, NCM811, and S cathodes, the batteries have demonstrated excellent capacity retention and cycling stability. More importantly, a volumetric energy density of 478 Wh L-1 and 78% capacity retention after 310 cycles have been achieved by using a S/LixLLTO-Li pouch cell. This work provides a feasible avenue to provide large-scale preparation of safe Li anodes for the next-generation pouch-type Li-S batteries as ideal power sources for flexible electronic devices.

Automated summary

A LiF-rich protection layer was developed in this study to enhance the safety and stability of Li metal anodes, enabling uniform Li deposition and inhibiting dendrite growth. When paired with different cathode materials, the batteries showed excellent capacity retention and cycling stability. A high energy density and long cycle life were achieved using a S/LixLLTO-Li pouch cell.