Taking one last look at 2011\u2019s fifth annual Electric Aircraft Symposium, your editor regrets the fits and starts in its coverage. Next week, we\u2019ll begin looking at the extraordinary presentations from this year\u2019s gathering.<\/p>\n
Huw W. Hampton-Jones from Oxis Energy<\/a>, a British company developing a Lithium Sulfur battery, claimed his firm\u2019s \u201ctechnology is based around the use of Lithium Sulphur to produce batteries which are superior in terms of energy, weight, cycle life, costs, ageing and safety.\u201d<\/p>\n Lithium sulfur is well known in military circles for providing primary (non-rechargeable) power to field operations. \u00a0Perlan I flew with SAFT 5590 primary batteries, partly because of their superior energy density compared to lithium-ion cells, and partly because of their greater resistance to thermal runaways, or self-igniting fires sometimes seen in lithium batteries. Weight was a significant concern on this high-altitude craft.<\/p>\n When working on the fringes of the battery selection effort for Perlan II, headed by Einar Enevoldson, James Murray and Eric Greenwell, this editor came to the conclusion that the same Li-S cells used five years before were still the lightest available. This was a bit disheartening, and illustrates the slow development that counters the high expectations EV enthusiasts share.<\/p>\n Mr. Hampton-Jones cautioned in his presentation that, \u201cIf the incidence of lithium cell-phone and laptop fires were applied to the larger pack for EVs, 1 out of 70,000 cars would explode.\u201d That\u2019s a daunting number and not very good odds. Luckily, car makers take steps to isolate individual cells, monitor and control things, and keep batteries from getting overcharged or over-taxed. Still, overall evidence is that despite two different types of highly flammable electrodes on board, the Lithium Sulfur battery is at least statistically less likely to self-ignite.<\/p>\n According to Hampton-Jones, Oxis\u2019 Lithium Sulfur battery also, compared to Lithium-ion units, costs less \u2013 about 30 cents per Watt-hour and stores more energy \u2013 around 350 Watt-hours per kilogram. Lithium cells cost from 80 cents to $1.00 per W\/hr and hold around 200 Whr\/kg.<\/p>\n Oxis works with a number of partners to manufacture and assemble the various components in the batteries, and is integrating their use into a variety of applications. INDUCT<\/a>, for instance, is a car maker using Oxis batteries.<\/p>\n