John Petersen is one of the sharpest people writing about battery technology, his infatuation with lead-acid notwithstanding.
Last week Energy Secretary Steven Chu addressed the United Nations Climate Change Conference in Cancun. After watching the video presentation several times I can't help but wonder whether the Secretary didn't politely caution his audience that lithium-ion batteries are a dead-end electric drive technology. I could be misinterpreting Secretary Chu's remarks, but if you own stock in a lithium-ion battery developer like A123 Systems (AONE), Ener1 (HEV), Valence Technologies (VLNC) or Altair Nanotechnologies (ALTID), or are considering any of these companies for your portfolio, the discussion that starts 25 minutes into the following video could be very important.
My impressions, observations and interpretations are summarized below.
Secretary Chu began his electric drive remarks with a politically correct but specious comparison of vehicle efficiencies that followed the EPA fuel efficiency party line I criticized in Alice in EVland, Part II. The numbers simply don't work unless you ignore efficiency losses and emissions on the utility side of the electric meter. Ignoring the political posturing, the most curious and troubling aspect of the Secretary's electric drive remarks was his description of what it would take for electric drive to be competitive with internal combustion:
"And what would it take to be competitive? It will take a battery, first that can last for 15 years of deep discharges. You need about five as a minimum, but really six- or seven-times higher storage capacity and you need to bring the price down by about a factor of three. And then all of a sudden you have a comparably performing car; let's say a mid-sized car which has a comparable acceleration and a comparable range."
Now, how soon will that be? Well, we don't know, but the Department of Energy is supporting a number of very innovative approaches to batteries and its not like its 10 years off in the future, in my opinion. It might be five years off in the future. It's soon. Meanwhile the batteries, the ones we have now, will drop by a factor of two within a couple of years and they're gonna get better. But if you get to this point, then it just becomes something that's automatic and I think the public will really go for that."
While Secretary Chu was explaining these bottom-line technical and economic requirements, the following summary text was superimposed on a background slide that compared the relative energy densities of common fuels.
"A rechargeable battery that can last for 5,000 deep discharges, 6-7 x higher storage capacity (3.6 Mj/kg = 1,000 Wh) at 3x lower price will be competitive with internal combustion engines (400 - 500 mile range)."
The unspoken yet undeniable truth in Secretary Chu's presentation is that it's impossible to achieve energy densities of 1,000 Wh/kg with lithium-ion batteries. The following graph comes from the Electricity Storage Association and shows the relative energy densities of various battery chemistries on a logarithmic scale. While the graph uses kilowatt-hours per ton and per cubic meter for its scale, the magic of the metric system means that the watt-hours per kilogram and per liter end up at the same root numbers, just three orders of magnitude smaller.
Lithium-ion battery developers have made great strides over the last few years when it comes to cycle-life and safety. In every case, however, the gains have come at the cost of reduced energy density....MORE, including the Secretary Chu video