Skip to main content

Magnetically controlled battery could store energy for power grids



Images of the magnetic fluid containing superparamagnetic nanoparticles that move with an applied magnetic field. (e) shows the color difference between a pure polysulfide solution without magnetic nanoparticles (left) and a biphasic magnetic polysulfide solution (right) with a high and low concentration of polysulfide. Credit: Li, et al. ©2015 American Chemical Society


Scientists have built a battery containing a magnetic fluid that can be moved in any direction by applying a magnetic field. The magnetically controlled battery concept could be especially useful for flow batteries, where it could eliminate the need for the pumps that are typically required for moving the electrolyte from an external storage tank to the inside of a power stack to provide electricity. Flow batteries are being actively researched as large-scale energy storage devices for power grids, where they could store energy captured by intermittent alternative energy sources such as wind and solar.

The researchers, led by Yi Cui, Professor at Stanford University, have published a paper on the new magnetically controlled battery in a recent issue of Nano Letters.
"The greatest significance of our work lies in the innovative idea of using a magnetic field to control and enhance the mass and electron transport in a battery system," lead author Weiyang Li, previously at Stanford University and now at Dartmouth College, told Phys.org.
The key to the new battery design is the composition of the catholyte (the part of the electrolyte near the cathode), which contains lithium polysulfide mixed with magnetic . By applying a magnetic field, the researchers could pull the nanoparticle colloids in a desired direction, and due to strong binding between the iron oxide nanoparticles and the lithium polysulfide, the lithium polysulfide could be pulled along with the magnetic particles. This creates a biphasic magnetic solution, with a high concentration of polysulfide on one side of the container and a low concentration on the other.
Magnetically moving the electrochemically active materials in the electrolyte in this way would be very useful for flow batteries because the goal in these batteries is to move the active molecules so that they are in close contact with a current collector. This allows a greater number of the active materials to be used, resulting in a higher energy density for the battery.
Tests showed that the new magnetic fluid containing the  nanoparticles leads to improvements in several areas compared to an electrolyte without the nanoparticles, including a higher capacity (350 mAh/g vs. 126 mAh/g), which corresponds to a high volumetric energy density of 66 Wh/L, as well as better capacity retention and efficiency. The researchers attribute these improvements to the magnetic field's ability to transport more polysulfide molecules and to minimize the undesirable "shuttle effect"—which occurs when the polysulfide molecules shuttle to the anode—because the magnetic nanoparticles can anchor the polysulfide molecules at the cathode.
http://phys.org/news/2015-10-magnetically-battery-energy-power-grids.html
The researchers demonstrate that the magnetic fluid forms a concentrated polysulfide phase that moves in the direction of a magnet. Credit: Li, et al. ©2015 American Chemical Society

In the future, if the -control concept could replace the need for pumps in flow batteries, it would eliminate parasitic pumping losses, which in turn could significantly increase the efficiency and lower the cost of these .
"Our idea can be potentially applied to a wide range of flow battery systems, not only confined to the lithium polysulfide  in our paper," Cui said. "We are planning to extend our idea to other  systems for electric grids, portable electronics, and transportation, as well."

Comments

Post a Comment

Popular posts from this blog

This strange mineral grows on dead bodies and turns them blue

If you were to get up close and personal with Ötzi the Iceman – the 5,000-year-old mummy of a  tattooed ,  deep-voiced  man who died and was frozen in the Alps – you’d notice that his skin is flecked with tiny bits of blue. At first, it would appear that these oddly bluish crystal formations embedded in his skin are from freezing to death or some other sort of trauma, but it’s actually a mineral called  vivianite  (or blue ironstone) and it happens to form quite often on corpses left in iron-rich environments. For Ötzi, the patches of vivianite are  from him resting  near rocks with flecks of iron in them, but other cases are way more severe. According to Chris Drudge at Atlas Obscura , a man named John White was buried in a cast iron coffin back in 1861. During those days, coffins often had a window for grieving family members to peer inside even if the lid was closed during the funeral. Sometime after he was buried, that window broke, allow...
Post a Comment
Read more

It's Official: Time Crystals Are a New State of Matter, and Now We Can Create Them

Peer-review has spoken. Earlier this year , physicists had put together a blueprint for how to make and measure time crystals - a bizarre state of matter with an atomic structure that repeats not just in space, but in time, allowing them to maintain constant oscillation without energy. Two separate research teams managed to create what looked an awful lot like time crystals  back in January,  and now both experiments have successfully passed peer-review for the first time, putting the 'impossible' phenomenon squarely in the realm of reality. "We've taken these theoretical ideas that we've been poking around for the last couple of years and actually built it in the laboratory,"  says one of the researchers , Andrew Potter from Texas University at Austin. "Hopefully, this is just the first example of these, with many more to come." Time crystals  are one of the coolest things physics has dished up in recent months, because they point to a...
Post a Comment
Read more

The Dark Side Of The Love Hormone Oxytocin

New research shows oxytocin isn't the anti-anxiety drug we thought it was. Oxytocin, the feel-good bonding hormone released by physical contact with another person, orgasm and childbirth (potentially encouraging  monogamy ), might have a darker side. The  love drug  also plays an important role in intensifying  negative emotional memories  and increasing feelings of fear in future stressful situations, according to a new study. Two experiments performed with mice found that the hormone activates a signaling molecule called extracellular-signal-related kinases (ERK), which has been associated with the way the brain  forms memories   of fear . According to Jelena Radulovic, senior author on the study and a professor at Northwestern University's medical school, ERK stimulates fear pathways in the brain's lateral septum, the region with the highest levels of oxytocin. Mice without oxytocin receptors and mice with even more oxytocin receptors tha...
Post a Comment
Read more