Rational Design of Interfaces for High Current-Density Lithium Metal Anodes

The practical application of a lithium (Li) metal anode is limited by the uncontrolled growth of Li dendrites during cycling. Here, we present a rationally designed trilayer protective coating for stabilizing the Li anode at high current densities. The protective coating is designed to consist of silver (Ag), lithium fluoride (LiF), and poly(ethylene oxide) (PEO), in which the Ag layer facilitates rapid Li+ transfer and uniform deposition, benefiting high current density operations. The LiF layer suppresses direct anode-electrolyte reactions while offering mechanical robustness to suppress the formation of dendrites. The PEO layer acts to enhance the protective coating's toughness, which prevents detachment of Ag during lithium plating and stripping. As a result, the Li//Li symmetric cell can stably cycle for 1200 h at a high current density of 20 mA cm-2. Additionally, the full cell of Li//LFP shows stable cycling for 1000 cycles at 1.09 mA cm-2 (2.50 mg cm-2) and 80 cycles at 5 mA cm-2 (11.50 mg cm-2). This study introduces a new technique for designing a solid electrolyte interphase (SEI) to the scientific community by successfully compositing alloyed, inorganic, and organic layers.