Tesla Motors - Model S lithium-ion battery pack
Electric cars today are hampered by relatively short ranges, long charging times, and higher costs than comparable internal-combustion models--all problems that stem from their battery packs.
Legions of researchers are trying to improve on the currently-dominant lithium-ion chemistry, hoping to increase energy density and lower cost.
But what if the batteries themselves aren't the problem?
A Boston-area startup believes it can revolutionize lithium-ion batteries by changing the way they're made.
24M claims its battery-manufacturing process can dramatically cut costs, as detailed in a recent report by Quartz.
When it starts commercial sales in two years, 24M believes it can cut the cost of a battery-manufacturing plant nearly ten-fold.
Nissan lithium-ion battery pack plant under construction, Smyrna, Tennessee, Jan 2011
It currently costs at least $100 million to put an entry-level lithium-ion cell fabrication plant into operation.
Tesla Motors' Nevada "Gigafactory"--billed as the biggest lithium-ion plant in the world--will cost an estimated $5 billion.
The company was started in 2010 by Yet-Ming Chiang, an MIT professor and founder of A123 Systems--the manufacturer that supplied cells to Fisker Automotive before going bankrupt in 2012.
Apparently not content with starting one cell maker, Chiang rounded up $12.5 million in private and Federal funding for 24M, and went to work on flow-cell batteries.
These rely on the flow of an electrolyte fluid between tanks to create electricity. Chiang wanted to employ this design, but with lithium-ion chemistry.
The flow-cell plan eventually proved unworkable, but it wasn't all wasted effort.
Nissan lithium-ion cell fabrication & battery pack assembly at Nissan plant in Smyrna, Tennessee
Researchers built several standard lithium-ion batteries for comparison purposes, which got them thinking about the way commercial cells are manufactured.
The standard method dates back to the first commercialized lithium-ion cell design, which was introduced by Sony in 1991 for handheld video cameras.
To make the cells, Sony re-purposed an assembly line used for cassette tapes.
It made good financial sense at the time, but also introduced inefficiencies that haven't been dealt with 24 years later.
Companies still use massive machines to coat material in an electrode slurry, drying it and adding an electrolyte.
Chiang and his collaborators decided to reduce the footprint of the equipment, the time needed to assemble cells, and improve the design of the cells themselves.
Tesla battery gigafactory site, Reno, Nevada, Feb 25, 2015 [photo: CC BY-NC-SA 4.0 Bob Tregilus]
Injecting the liquid electrolyte into cells from the start reportedly saves 22 hours of drying time.
And the method for applying the electrodes was reduced to a quick process involving a "tube, a plunger, and some Teflon."
Filler space in the cells not devoted to energy storage was also reduced from 35 percent to 8 percent, and the electrodes were made four times thicker, to increase energy density.
This resulted in a battery-making machine about the size of a refrigerator. The final commercial version, 24M claims, will be able to churn out a cell every two to 10 seconds.
Those cells will cost around $160 per kilowatt-hour, while the equipment itself will cost just $11 million.
Rendering of Tesla battery gigafactory outside Reno, Nevada, Sep 2014
The company intends to start selling cells in two years, but only for stationary energy storage--not electric cars.
If its plans change, 24M could have a major impact. By 2020, the company expects the cost of its cells to drop to $85 per kWh.
That's comfortably below the $100 per kWh many analysts believe is the point where electric cars become cost competitive with gasoline and diesel cars.
[hat tip: Jane Grenier]