Jim at The Energy Blog remains somewhat skeptical about the latest news on EEStor.
EEStor is believed to have had trouble developing its product, an ultracapacitor claimed to have a specific energy of 280 watt-hours per kilogram, compared to a lithium ion battery with about 120 watt-hours and a lead-acid gel battery, with only 32 watt hours. (Although ElectroVaya claims 330Wh/kg, so they may not be alone)
The problem is believed, by some, to be in producing the ultra-pure barium-titanate used in the capacitor, which is the key to having the high specific energy. A January 2007 announcement indicated that 1) An automated production line had been proven to meet the requirements for precise chemical delivery, purity control, parameter control and stability and 2) they had completed the initial milestone of certifying purification, concentration, and stability of all of its key production chemicals notably the attainment of 99.9994% purity of its barium nitrate powder. At that time they claimed that they would be shipping product to Zenn in 2007, a year earlier than indicated in the current announcement.
EEStor's recently announced collaboration with Lockheed Martin, which gives the company credibility and is a further indication that the company is making progress. The current announcement seems to be in agreement with the timing indicated in the Lockheed Martin announcement, although, based on past performance, a wait and see position must be held.