Composite protective layer for Li metal anode in high-performance lithium–oxygen batteries

• Composite protective layer (CPL) was introduced at the Li surface in Li–O2 battery.
• The CPL suppresses electrolyte decompositions at the Li metal surface.
• The CPL significantly improves the cycling stability of Li–O2 battery.
• The CPL can be an effective design platform for high-performance Li–O2 batteries.

Lithium–oxygen batteries are of great interest because of their very high-energy density; however, they present many challenges, one of which is the low cycling stability of a lithium (Li) metal anode. Here, we report a composite protective layer (CPL) comprising Al2O3 and polyvinylidene fluoride-hexafluoro propylene for a Li metal anode that resulted in a dramatic enhancement of the cycling stability of a lithium–oxygen battery. A cell with the CPL-coated Li metal anode exhibited more than 3 times higher discharge capacity at the 80th cycle compared to a cell without the CPL. X-ray photoelectron spectroscopy measurements for the cycled lithium metal anodes confirm that the CPL effectively suppressed electrolyte decomposition at the surface of the Li metal anode.

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