Time to get charged up about advances in smaller, faster lithium-ion batteries
Battery advances seems to be flowing as fast as electrons these days — and super fast charging batteries may hit the market in as little as 2 to 3 years. And that’s critical because the car of the very near future, plug in hybrids, are a core climate solution (see here). And electricity is the only alternative fuel that can lead to energy independence (here).
Scientists at the Massachusetts Institute of Technology report in a March 12 Nature article, “Battery materials for ultrafast charging and discharging” (see here, $ub. req’d):
It is typically believed that in electrochemical systems very high power rates can only be achieved with supercapacitors, which trade high power for low energy density as they only store energy by surface adsorption reactions of charged species on an electrode material. Here we show that batteries which obtain high energy density by storing charge in the bulk of a material can also achieve ultrahigh discharge rates, comparable to those of supercapacitors … A rate capability equivalent to full battery discharge in 10-20 s can be achieved.
The ability to charge and discharge batteries in a matter of seconds rather than hours may make possible new technological applications and induce lifestyle changes.
Impressive. You can read the M.I.T. release here. One of the biggest benefits to plug in hybrid electric vehicles (PHEVs) and electric vehicles is one not discussed by the researchers. As EV World editor Bill Moore explains:
Being able to charge and discharge rapidly, especially if there is no degradation of the cell, is of value for improving energy recovery from an EV’s regenerative braking system, only about 10 percent of which is typically recaptured from the vehicle’s kinetic energy. It also will be useful in improving vehicle acceleration. Blended-mode plug-ins should also benefit as a result, though series hybrids like the Volt probably won’t, as they require more energy-dense cells.
Where MIT’s “breakthrough” can be of real significance is in its purported cost advantage. The developers contend that their new coating material reduces the need for other mediating compounds in the battery, and since it can be applied using current manufacturing processes, battery costs can be reduced.
It is also worth noting that the lithium chemistry M.I.T. is working with does not suffer from overheating, as current lithium batteries can.
The best news about M.I.T.’s advance is that “Because the material involved is not new — the researchers have simply changed the way they make it — Ceder believes the work could make it into the marketplace within two to three years.” In that sense, this may be more of an innovation than a breakthrough, though neither term is well defined.
As for the ability to charge the entire PHEV or EV quickly, the authors note:
… the rate at which very large batteries such as those planned for plug-in hybrid electric vehicles can be charged is likely to be limited by the available power: 180 kW is needed to charge a 15 kWh battery (a typical size estimated for a plug-in hybrid electric vehicle) in 5 min.
Well, 15 kilowatt-hours is about what the Chevy Volt needs — but the GM plug in is designed to go 40 miles on a charge, and that is almost certainly a longer range than most other early PHEVs will have (see here). Of course, super fast charging is not really what PHEVs need to be viable. Lower cost is. Moore notes:
Japan’s NEDO (New Energy and Industrial Technology Development Organization) has … issued a technology roadmap that sees battery costs eventually dropping significantly below current levels by 2020..
The roadmap forecasts the development will be focused on two types of batteries: an output density-oriented type intended for plug-in hybrid and hybrid cars, and an energy density-oriented type for electric cars.
Currently, energy-dense battery packs (not cells) are estimated to cost approximately US$2,016/kWh, NEDO researchers estimate. By 2020, their goal is to achieve a price of one-tenth that figure and to increase the Watt hours/kg two-and-half times, from 100Wh/kg to 250Wh/kg.
That would be a game changer indeed.
And for folks who really want to some really far out stuff, how about a real “breakthrough” announcement — a magnetic spin battery:
Researchers at the University of Miami and at the Universities of Tokyo and Tohoku, Japan, have been able to prove the existence of a “spin battery,” a battery that is “charged” by applying a large magnetic field to nano-magnets in a device called a magnetic tunnel junction (MTJ) …
The device created by University of Miami Physicist Stewart E. Barnes, of the College of Arts and Sciences and his collaborators can store energy in magnets rather than through chemical reactions. Like a winding up toy car, the spin battery is “wound up” by applying a large magnetic field -no chemistry involved. The device is potentially better than anything found so far, said Barnes.
“We had anticipated the effect, but the device produced a voltage over a hundred times too big and for tens of minutes, rather than for milliseconds as we had expected,” Barnes said. “That this was counterintuitive is what lead to our theoretical understanding of what was really going on.”
The secret behind this technology is the use of nano-magnets to induce an electromotive force. It uses the same principles as those in a conventional battery, except in a more direct fashion. The energy stored in a battery, be it in an iPod or an electric car, is in the form of chemical energy. When something is turned “on” there is a chemical reaction which occurs and produces an electric current. The new technology converts the magnetic energy directly into electrical energy, without a chemical reaction. The electrical current made in this process is called a spin polarized current and finds use in a new technology called “spintronics.”
The new discovery advances our understanding of the way magnets work and its immediate application is to use the MTJs as electronic elements which work in different ways to conventional transistors. Although the actual device has a diameter about that of a human hair and cannot even light up an LED (light-emitting diode-a light source used as electronic component), the energy that might be stored in this way could potentially run a car for miles. The possibilities are endless, Barnes said.
I generally don’t post these way out “breakthrough” announcements since so few make it to commercial fruition. But it it is indicative of how exciting and vibrant — and well funded — the advanced battery sector is.
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