For lithium mining, it is not mainly the carbon footprint - it is the overall environmental cost. Lithium mining using the brine/surface drying method is rather cheap and effective, but it uses approximately 500,000 gallons per ton of lithium. In Chile’s Salar de Atacama, mining activities consume 65 per cent of the region’s water. That is having a big impact on local farmers – who grow quinoa and herd llamas – in an area where some communities already have to get water driven in from elsewhere.
There’s also the potential – as occurred in Tibet – for toxic chemicals to leak from the evaporation pools into the water supply. These include chemicals, including hydrochloric acid, which are used in the processing of lithium into a form that can be sold, as well as those waste products that are filtered out of the brine at each stage.
Research in Nevada found impacts on fish as far as 150 miles downstream from a lithium processing operation. Research in Australia found that only two per cent of the country’s 3,300 tons of lithium-ion waste was recycled.
Cobalt and nickel, also used in electric cars, may be even more problematic. Cobalt is found in huge quantities in the Democratic Republic of Congo and central Africa, and hardly anywhere else. You can literally just dig up the land and find cobalt, so there’s a very strong motivation to dig it up and sell it, and a a result there is motivation for unsafe and unethical behavior. The Congo is home to ‘artisanal mines’, where cobalt is extracted from the ground by hand, often using child labor, without protective equipment.
What is needed is new battery chemistries that replace cobalt, lithium, and nickel with more common and less toxic materials, such as the sodium chemistry being researched and developed at the University of Texas. It is interesting that John B. Goodenough, inventor of the lithium cobalt oxide and lithium iron phosphate chemistries used in the lithium-ion (Li-ion) battery, is working on this - he has stated his regret for the environmental issues his batteries have caused.
https://www.wired.co.uk/article/lithium-batteries-environment-impact