Researchers at Stanford University are working on a new rechargeable zinc-air battery that could provide a low cost energy storage alternative to the current favorite, lithium-ion. Zinc-air batteries have great promise due to the cheapness and abundance of their basic materials along with a relatively high energy density, but until now the technology has been bedeviled by “sluggish” catalytic reactions. Solving that problem could greatly expand the market for wind and solar power, including electric vehicle batteries and utility-scale energy storage.
Lithium-Ion Still #1
Before we dig into the Stanford zinc-air battery, let’s be clear that lithium-ion batteries are not going away any time soon. Though the Stanford team claims a much higher energy density for zinc-air there is plenty of room for improvement in li-ion battery technology, one recent example being the development of a new electrode that resolves the notorious “lithium traffic jam” issue.
If anything, the hitch will probably be the issue of lithium supply. Currently, the US depends heavily on imported lithium, creating a significant vulnerability to global market swings.
There should be some improvement in the near term, with the recent discovery of a huge lithium deposit in Wyoming and a coordinated effort by the Obama Administration to boost domestic lithium production. However, over the long term it’s tough to see how lithium alone could provide a stable platform for the exploding electric vehicle market, among other uses.
The Stanford Zinc-Air Solution
Zinc-air batteries work by churning ambient oxygen (aka “air”) with zinc in a liquid alkaline electrolyte to create an electrical charge. As the battery discharges it produces zinc oxide, which regenerates into zinc when the battery is recharged.
Problems with the technology include the aforementioned sluggishness of conventional catalysts used in zinc-air batteries, as well as the durability of the zinc electrodes.
To resolve those issues, the Stanford team came up with a new line of low-cost catalysts, including a nanocrystal-carbon nanotube combination as well as metal oxides sourced from non-precious materials.
The result is a zinc-air battery that uses a cobalt-oxide air catalyst for discharging and a nickel-iron hydroxide catalyst for recharging, which according to lead researcher Hongjie Dai, has a “high specific energy density more than twice that of lithium-ion technology.”
Zinc-Air Batteries, Here And Now
Dai foresees some additional obstacles in the Stanford team’s path to commercializing the technology, but in the mean time zinc-air batteries are already marching into the market.
One company we’ve been following here at CleanTechnica is Eos Energy Storage, which has been working to resolve the zinc-air durability issue.
Just last month, Bloomberg reported that Eos has reached a deal with New York City’s electricity supplier, Consolidated Edison, to test the company’s utility scale zinc-air battery.
According to Bloomberg reporter Andrew Herndon, the test will take place next year under a $250,000 matching grant from the New York State Research and Development Authority.
To give you an idea of how “interesting” zinc-air technology could get in terms of a low-cost alternative for utilities to provide power during peak use periods, Herndon reports that batteries are competitive with the existing system of extra power plants, transmission lines and distribution points at a price point of about $300 per kWh, and Eos intends to beat that by a wide margin, coming in at only $160 per kWh.
As for the battery’s basic materials, air is air, and zinc is found plentifully in the U.S. and Canada, as well as Australia.
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