The charge-discharge behavior of a lithium metal anode in propylene carbonate (PC) electrolyte containing added C02 was investigated using in situ ac impedance measurements during galvanostatic cycling. In PC electrolyte with C02, the anode's cycle life was twice as long and its charge transfer resistance was smaller than in the same electrolyte without C02. These enhancements are observed only when lithium is electrodeposited in the presence of C02 on nickel substrate; the enhancement does not occur when lithium is deposited without C02 and is cycled with C02. Even large amounts of H20 in the electrolyte during cycling do not adversely affect the cycle life enhancement by C02. The C02 enhancement seems to be due to products formed by reaction of lithium with C02 on the electrodeposited lithium surface.
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