The 800-km battery lithium-ion batteries are played out. Next up: lithium-air

Proposition: Electric cars will remain mostly niche products until they have a range of 800 kilometers, or roughly 500 miles, with an affordable battery. That's as far as most people would want to drive in a day, and then they have all night to recharge. That's how we came up with a figure of 800 km-or a nice round 500 miles-as the goal for our R&D project, Battery 500. It began in 2009 at the IBM Almaden Research Center, in San Jose, Calif., and has grown since then into a multinational partnership with commercial and academic participants in Europe, Asia, and the United States. It is based on metal-air technology, which packs far more energy into a battery of a given mass than today's state-of-the-art technology, the lithium-ion battery. We are still years away from commercialization, but we have made enough progress to predict that these batteries could be used in cars in the foreseeable future. Why are we so confident? Read on.