Aug
13
Moving The Lithium Ion Battery Goalpost
August 13, 2012 | 1 Comment
GM’s CEO Dan Akerson said Thursday the small battery company Envia backed in part by General Motors is working on breakthrough technology that could power an electric car 100 or even 200 miles on a single charge in the next two-to-four years.
Because of the material’s stability at higher voltages, it’s able to operate at high capacities with a long cycle life. The combination of high capacity and low cost metals helps to significantly lower the price per kilowatt-hour (kWh) of energy storage.
Envia 45ah-cell Battery Voltage and Capacity. Click image for the largest view.
With more energy in each battery, the number of batteries required decreases, setting up Envia to dramatically reduce the overall cost of the battery. Envia’s proprietary nano coating process and high voltage electrolyte and electrolyte additive technology combined suggests a high cycle life and long calendar life.
Akerson is also quoted to have said, “I think we’ve got better than a 50-50 chance to develop a car that will go to 200 miles on a charge. That would be a game changer.”
Envia’s technology enables a 2-3X improvement in vehicle range compared other Lithium cell chemistries peaking at 180 Wh/kg.
Envia commissioned the Advanced Research Products Agency – Energy (ARPA-E) to perform verification & validation testing who then tasked Naval Service Warfare Center, Crane Division Test & Evaluation Branch to do the work.
The test sought verification of cell capacity and energy density at cycle number10 and cycle number 3, 100% depth of discharge (DOD), as well as cell capacity and energy density at cycle number 3, 80% DOD. Before delivery Envia ran one test cycle making the ARPA-E start at cycle number 2.
Envia sent prototype lithium pouch rechargeable cells. The cells have a capacity of 46 Ah and an energy density of 400Wh/Kg. The cell’s dimensions are approximately 97 mm (3.82”) wide, 190 mm (7.48”) long and 10 mm (0.4”) thick. The cell’s approximate weight is 365 (0.80 pounds) grams. It’s not very big and not very heavy.
Obviously the test cleared the claims of an energy density of 400Wh/Kg and capacity of 46 Ah. Envia will provide the full test report on request.
Envia is building out three proprietary technologies, the cathode, anode and electrolytes.
The cathode has a unique cathode chemistry based on a unique crystal structure. It’s High Capacity Manganese Rich (HCMR™) cathode has excellent stability at high voltages and can access high capacities with long cycle life. The cathode is built on Argonne’s layered-layered chemistry to fine tune the composition of Ni, Co, Mn and Li2MnO3. Envia innovated on particle morphology (particle size, shape, distribution, tap density & porosity) and developed novel nano coatings to enhance cycle life & safety.
The anode was developed with an ARPA-E grant using a silicon-carbon nano composite anode. This anode will complement Envia’s high capacity cathode and is ready for commercialization in 2012. This is the “miracle” material, silicon that doesn’t swell and self-destruct when infused with the lithium.
The electrolyte is stable up to a voltage of 5.2V. Usually high voltage operation brings an increase in oxidation currents, a kind of ‘corrosion’ effect. Envia’s high voltage electrolyte showed stability up to 5.2V without any rapid increase in the oxidation currents.
These complimentary technologies suggest Akerson could very well have it right. GM is sure that the battery will be able to take a car 100 miles within a couple of years. Akerson and other seem to believe that with “some luck” the battery range could be double that.
That kind of range could greatly simplify a short to medium range personal transport vehicle. No complex and expensive parallel hybrid technology, not even a small generator set for series hybrid recharge design. A city or suburban vehicle could be quite inexpensive – the battery size would be halved and the cost of that halved the cost once more.
Envia isn’t a sure thing yet; Akerson thinks there’s better than a 50-50 chance the 200-mile range is possible.
But this is good enough to consider: 100 mile stop and go city driving, or 150 mile 75 mph road work, both with the a/c or heat on. Eventually the manufacturers are going to realize that a design with this level of performance will sell when a portable generator set is an option or a rental for long trips. A slide or drop in generator that would keep a vehicle going 4 more hours at 75 to range out 450 miles would defeat most any objection.
EVs are coming. Lots more issues, temperatures, terrain and peak speeds and the like, but given the capacity and some innovation the manufacturers will get there.
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it sounds amazing! Looking forward to it very soon!