Li-Ion is nearly 100% recyclable, and there has been no study that actually looked at the carbon footprint of manufacturing batteries while citing evidence to back up the numbers used. The most high-profile study made a complete guess on manufacturing emissions.
The Tesla Gigafactory is supposed to be run almost entirely on RE. Tesla is also sourcing as much raw material from NA as possible, including the lithium from just down the road. EVs aren't magical, of course, there will always be a cost to manufacture them, and their "greenness" is entirely dependent on the fuel used to generate the electricity. One positive for Tesla is that their battery packs appear that they will last much longer than anyone anticipated, and the longer the pack is in use, the lower its carbon footprint.
As for Elio, if they can meet their efficiency guidelines, and replace someone's single occupancy commuter vehicle they will definitely be making a huge improvement on the state of emissions. The Avg. US new car is only something like 26mpg...