Still the most promising I've heard of is Solid Energy Systems. They claimed to be selling batteries to the aerospace field already. In their last presentation

Still the most promising I've heard of is Solid Energy Systems. They claimed to be selling batteries to the aerospace field already. In their last presentation it seemed like their challenge is cycle life, but that it's improving. But there's been a while since there's been any news from that company. http://www.solidenergysystems.com http://www.solidenergysystems.com