The first version of your post said that lithium ion batteries were toxic in production and disposal (both claims entirely false). You've now changed the entire comment to CO2 output for battery production (even though battery production will continue to decline in CO2 impact as grid energy sources continue to tilt towards renewables).

> Therefore, the study has calculated that a fossil fuel vehicle can currently drive for more than eight years before it reaches the same environmental impact of a Tesla. For the Nissan Leaf, with its smaller capacity battery, this figure comes in at three years.

Both Teslas and Leafs will be on the road beyond the eight and three years you quoted, putting their production at a net positive even before the above mentioned improvements take place.