Carbon film covering originated from fullerene C60 on the surface of lithium metal anode for lithium secondary batteries

Carbon films from fullerene C₆₀ were coated on the surface of lithium metal for the anode of lithium secondary battery. In order to investigate the relationship between the electrochemical characteristics of the carbon films and deposition technique, three different vacuum techniques were employed such as RF (radio frequency)—magnetron sputtering of C₆₀, plasma assisted thermal evaporation of C₆₀ and ion beam assisted thermal evaporation of fullerene C₆₀. From the physical and chemical characterization tests, we found that the carbon films produced by those above techniques mainly consist of sp²/sp³ hybridized amorphous carbons. Electrochemical tests implied that the cyclic performance was enhanced by the fullerene C₆₀ coating on lithium metal anode in comparison to the pure lithium metal one. This enhanced performance is due to the formation of thin carbon film on the surface of lithium metal anode which plays a role as a passive layer against the side reaction between lithium metal and the electrolyte.