Energy independence, a reduction in greenhouse gas emissions, lower fuel costs: All of these promises are factors behind the rise in electric vehicles' popularity. Unfortunately, they're more fiction than fact. Here's why, and how it could affect companies like Tesla Motors (NASDAQ: TSLA ) .Do you want cancer with that battery?Recently, the Environmental Protection Agency and the U.S. Department of Energy undertook a study to look at the environmental impact of lithium-ion batteries for EVs. The study showed that batteries that use cathodes with nickel and cobalt, as well as solvent-based electrode processing, have the highest potential for environmental impacts, including...