Cobalt-Phthalocyanine-Derived Molecular Isolation Layer for Highly Stable Lithium Anode.

The uneven consumption of anions during the lithium (Li) deposition process triggers a space charge effect that generates Li dendrites, seriously hindering the practical application of Li-metal batteries. We report on a cobalt phthalocyanine electrolyte additive with a planar molecular structure, which can be tightly adsorbed on the Li anode surface to form a dense molecular layer. Such a planar molecular layer cannot only complex with Li ions to reduce the space charge effect, but also suppress side reactions between the anode and the electrolyte, producing a stable solid electrolyte interphase composed of amorphous lithium fluoride (LiF) and lithium carbonate (LiCO ), as verified by X-ray absorption near-edge spectroscopy. As a result, the Li|Li symmetric cell exhibits excellent cycling stability above 700 h under a high plating capacity of 3 mAh cm . Moreover, the assembled Li|lithium iron phosphate (LiFePO , LFP) full-cell can also deliver excellent cycling over 200 cycles under lean electrolyte conditions (3 μL mg ).