On 27 Oct 2019 at 20:58, Paul Wujek via EV wrote: > Thorough take-down of that article printed in British newspapers last week:
That was pretty entertaining and detailed, but you don't need to sit through 27 minutes and 38 seconds of demonstrations of how al-air batteries work to debunk this story. Here's a quick read: https://theness.com/neurologicablog/index.php/aluminum-air-batteries/ Alternatively, you can read below what I wrote back to a friend of mine in Europe who heard about this "breakthrough" from one of her UK-based friends. I saw that story too. It was all over the place a week or so ago. It's the usual thing that popular media love, "Hey, look, this guy just invented what the battery engineers couldn't, and he did it in his garage!" tale. First, let's clarify something that the Daily Fail article kind of glosses over. Trevor Jackson didn't invent the aluminum-air battery. The basic design has been around for at least 50 years. It's in the public domain, so anybody can make one and offer it for sale. At first glance, al-air batteries look like a good idea for EVs because they have high specific energy (ratio of stored energy to weight). Unfortunately, they also have some pretty intractable problems. The Fail article says right in the headline, "1,500 miles without needing to charge." That might be true, because you can't recharge an al-air battery, full stop. Al-air is a primary (non-rechargeable) cell. We're talking about a glorified flashlight cell here. When it runs flat, you have to physically replace the battery, or at least the almuminum electrodes and the liquid electrolyte, which amounts to rebuilding the battery. So you couldn't plug it in at home. Nor could you go to a gas station, or even a charging point. "Refueling" an al-air EV would require yet another whole new fueling infrastructure, either rebuilding or exchanging the vehicle's entire battery. Another problem, to me the killer, is that the al-air battery is grossly inefficient. It takes a lot of energy to reduce bauxite into aluminum, and you only get 15-20 percent of that energy back from the metal when you oxidize it in the battery. That's on par with the energy efficiency of the gasoline engines of 50 years ago. (Today a really well designed hybrid gas car can hit 30% efficiency in the right circumstances, as long as you don't count all the energy used to find the crude, pump it, transport it, refine it into gasoline, transport the gas to the filling station, and pump it into the car.) By comparison, a lithium ion battery is about 99% efficient between 20% and 80% state of charge. (So is a lead battery, BTW.) Another problem: Al-air's specific power (ratio of power output in Watts to weight) is low. In an EV, it can't deliver electricity fast enough for the kind of acceleration that people expect from their cars. You can fix this by adding a rechargeable "buffer" battery with high specific power to the EV. When you accelerate or climb a hill, the buffer battery does the hard work. But this isn't as simple as it sounds. For example, if you make the buffer battery too small, it won't have enough energy for some kinds of driving. Imagine having to stop half way up a long hill, so your battery can catch up! The extra battery and hardware to manage it adds size, weight, complexity, and expense to the EV. Finally, al-air's electrolyte is caustic. It has to be, because it's essentially dissolving the aluminum to release its embedded energy. The usual electrolyte is sodium hydroxide -- also known as lye. You really don't want that stuff splashing and puddling round the scene in a collision. Resarchers have been working on these problems for decades. Unique Mobility in Colorado collaborated with AlCan on an experiment with al-air electric vehicle batteries in the 1980s. I visited them and saw their test mule, which they'd abandoned after deciding that it wasn't practical to commercialize the al-air process. This supposed inventor claims he's developed a safer electrolyte. Unfortunately, he won't tell us what it is, so there's no way to determine the validity of his claim. Even if it's totally on the up and up, I don't see that he's solved the other problems, in particular the lousy efficiency. The bottom line is that al-air batteries for EVs have some major problems, and, at best, this guy's "invention" MIGHT solve one of them. MIGHT. If you want an EV, for goodness sake don't hold your breath waiting for this miracle battery. I promise that regardless of what the article says, you're not going to see it in EVs next year. Try "never." David Roden - Akron, Ohio, USA EVDL Administrator = = = = = = = = = = = = = = = = = = = = = = = = = = = = = EVDL Information: http://www.evdl.org/help/ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Note: mail sent to "evpost" and "etpost" addresses will not reach me. To send a private message, please obtain my email address from the webpage http://www.evdl.org/help/ . = = = = = = = = = = = = = = = = = = = = = = = = = = = = = _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub ARCHIVE: http://www.evdl.org/archive/index.html INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
