The problems will come when Li batteries are *really* popular for cars. There is nowhere near enough Li to supply even a fraction of the ultimate demand. Researchers might spend their timer more profitably looking at Al and Mg.
Who says battery technology can't keep up? With research like this concentrating on ways to boost existing lithium ion batteries, plus efforts elsewhere to craft lithium-air and more exotic formulations, I predict a bright future for battery technology. Will battery technology ever catch up to Moores Law? What do you think?