The only component of the battery which contains Lithium is the cathode, which according to the article you linked is a little less than 1/3 of the material cos

The only component of the battery which contains Lithium is the cathode, which according to the article you linked is a little less than 1/3 of the material cost, or around 20% of the total cost. The battery chemistry which contains the most Lithium is Lithium Cobalt Oxide, which by weight is approximately 7% Lithium and 60% Cobalt. Even though Lithium is vastly more expensive than Cobalt, Cobalt still accounts for the majority of the cathode material cost. So it seems like Lithium accounts for at most 10% of the cost of the battery.