A research team from the Stanford School of Engineering has just figured out how to stabilize the lithium in a lithium-ion battery, and that could help bring the typical EV down to the level of mainstream affordability. The team is looking at a price point of $25,000 for an EV battery range of 300 miles, which would be competitive with a 40 mpg gasmobile.
The dream of extending EV battery range usually comes with a high price tag (here and here, for example), so the idea that longer range could actually bring down costs is of particular interest, especially considering that former Energy Secretary Steven Chu is a member of that Standford research team.
Standfords solution is a honeycomb of interlocking carbon nanospheres layered on to the lithium anode. At 20 nanometers thick youd need 5,000 layers of this nano-comb to equal the width of a human hair, but it seems to have gotten the job done.
The honeycomb structure is flexible enough to stabilize the anode surface as it expands during charging, and also while it contracts during discharge.
According to Stanford, the results so far look promising. In tests the new lithium anode reached 99 percent efficiency over the course of 150 charge/discharge cycles.
The figure of 99 percent is significant because a marketable battery needs to be 99.9 percent efficient over numerous charging cycles (thats Coulombic efficiency for those of you keeping score at home). Earlier attempts at lithium anodes have petered out pretty quickly, attaining a top mark of 99.6 percent at the beginning and dropping down to 50 percent efficiency after just 100 cycles.
In batteryspeak that figure of 99.6 percent is significantly lower than the desired 99.9 percent. By the same token Standfords achievement of 99 percent over 150 cycles is pretty impressive and it comes a lot closer to commercial viability, but it does fall short of the desired 99.9 percent mark.
The next steps for Standford include tinkering around with the electrolytes, perhaps trying out some new ones.
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