The battery is correctly seen as the Achilles' heal of electric vehicles. Now some recent innovations hold the promise of perhaps solving some persistent problems:
Recharging. Faster is better. See http://www.economist.com/node/18437910?story_id=18437910.
Self-Repairing. Lithium-ion batteries have a problem; they breakdown over time, and pose a risk of fire. Researchers have develop several options that allow the battery to repair itself, or to prevent the flow of electrons to stop the risk of fire. See http://aaas.confex.com/aaas/2011/webprogram/Paper3885.html.