Subscribe free to our newsletters via your
. 24/7 Space News .




ENERGY TECH
New flow battery to keep big cities lit, green and safe
by Staff Writers
Richland WA (SPX) Feb 26, 2015


Flow batteries produce power by pumping electrolytes - liquid solutions with dissolved chemicals - from external tanks into a central stack. PNNL's new zinc-polyiodide flow battery's electrolytes carry positively charged zinc ions and the negatively charged ions iodide and polyiodide. Image courtesy Pacific Northwest National Laboratory. Watch a video on the research here.

Ensuring the power grid keeps the lights on in large cities could be easier with a new battery design that packs far more energy than any other battery of its kind and size.

The new zinc-polyiodide redox flow battery, described in Nature Communications, uses an electrolyte that has more than two times the energy density of the next-best flow battery used to store renewable energy and support the power grid. And its energy density is approaching that of a type of lithium-ion battery used to power portable electronic devices and some small electric vehicles.

"With improved energy density and inherent fire safety, flow batteries could provide long-duration energy storage for the tight confines of urban settings, where space is at a premium," said Imre Gyuk, energy storage program manager at the Department of Energy's Office of Electricity Delivery and Energy Reliability, which funded this research. "This would enhance the resiliency and flexibility of the local electrical grid."

"Another, unexpected bonus of this electrolyte's high energy density is it could potentially expand the use of flow batteries into mobile applications such as powering trains and cars," said the study's corresponding author, Wei Wang, a materials scientist at DOE's Pacific Northwest National Laboratory.

Going with the flow
Both flow and lithium-ion batteries were invented in the 1970s, but only the lithium-ion variety took off at that time. Lithium-ion batteries could carry much more energy in a smaller space than flow batteries, making them more versatile. As a result, lithium-ion batteries have been used to power portable electronics for many years. And utilities have begun using them to store the increasing amounts of renewable energy generated at wind farms and solar power facilities.

But the high-energy lithium-ion batteries' packaging can make them prone to overheating and catching fire. Flow batteries, on the other hand, store their active chemicals separately until power is needed, greatly reducing safety concerns. This feature has prompted researchers and developers to take a serious second look at flow batteries.

Stacking up against the competition
Like other flow batteries, the zinc-polyiodide battery produces power by pumping liquid from external tanks into the battery's stack, a central area where the liquids are mixed. The external tanks in PNNL's new battery hold aqueous electrolytes, watery solutions with dissolved chemicals that store energy.

When the battery is fully discharged, both tanks hold the same electrolyte solution: a mixture of the positively charged zinc ions, Zn2+, and negatively charged iodide ion, I-. But when the battery is charged, one of the tanks also holds another negative ion, polyiodide, I3-.

When power is needed, the two liquids are pumped into the central stack. Inside the stack, zinc ions pass through a selective membrane and change into metallic zinc on the stack's negative side. This process converts energy that's chemically stored in the electrolyte into electricity that can power buildings and support the power grid's operations.

To test the feasibility of their new battery concept, Wei and his PNNL colleagues created a small battery on a lab countertop. They mixed the electrolyte solution, separating a black zinc-polyiodide liquid and a clear zinc-iodide liquid in two glass vials as miniature tanks. Hoses were connected between the vials, a pump and a small stack.

They put the 12-watt-hour capacity battery - comparable to about two iPhone batteries - through a series of tests, including determining how different concentrations of zinc and iodide in the electrolyte affected energy storage. Electrical capacity is measured in watt-hours; electric cars use about 350 watt-hours to drive one mile in the city.

More power to it
The demonstration battery put out far more energy for its size than today's most commonly used flow batteries: the zinc-bromide battery and the vanadium battery. PNNL's zinc-polyiodide battery also had an energy output that was about 70 percent that of a common lithium-ion battery called a lithium iron phosphate battery, which is used in portable electronics and in some small electric vehicles.

Lab tests revealed the demonstration battery discharged 167 watt-hours per liter of electrolyte.

In comparison, zinc-bromide flow batteries generate about 70 watt-hours per liter, vanadium flow batteries can create between 15 and 25 watt-hours per liter, and standard lithium iron phosphate batteries could put out about 233 watt-hours per liter.. Theoretically, the team calculated their new battery could discharge even more - up to 322 watt-hours per liter - if more chemicals were dissolved in the electrolyte.

Safe and versatile, but not perfect yet
PNNL's zinc-polyiodide battery is also safer because its electrolyte isn't acidic like most other flow batteries. It's nearly impossible for the water-based electrolyte to catch fire and it doesn't require expensive materials that are needed to withstand the corrosive nature of other flow batteries.

Another advantage of PNNL's new flow battery is that it can operate in extreme climates. The electrolyte allows it to work well in temperatures as cold as -4 degrees Fahrenheit and as warm as +122 degrees. Many batteries have much smaller operating windows and can require heating and cooling systems, which cut into a battery's net power production.

One problem the team encountered was a build-up of metallic zinc that grew from the central stack's negative electrode and went through the membrane, making the battery less efficient. Researchers reduced the buildup, called zinc dendrite, by adding alcohol to the electrolyte solution.

Managing zinc dendrite formation will be a key in enabling PNNL's zinc-polyiodide battery to be used in the real world. Wei and his colleagues will continue to experiment with different alcohols and other additives and use advanced instruments to characterize how the battery's materials respond to those additives. The team will also build a larger, 100-watt-hour model of the battery for additional testing.


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

.


Related Links
DOE/Pacific Northwest National Laboratory
Powering The World in the 21st Century at Energy-Daily.com






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





ENERGY TECH
In quest for better lithium-air batteries, chemists boost carbon's stability
Chestnut Hill MA (SPX) Feb 26, 2015
To power a car so it can travel hundreds of miles at a time, lithium-ion batteries of the future are going to have to hold more energy without growing too big in size. That's one of the dilemmas confronting efforts to power cars through re-chargeable battery technologies. In order to hold enough energy to enable a car trip of 300-500 miles before re-charging, current lithium-ion batteries ... read more


ENERGY TECH
Application of laser microprobe technology to Apollo samples refines lunar impact history

NASA releases video of the far side of the Moon

US Issuing Licenses for Mineral Mining on Moon

LRO finds lunar hydrogen more abundant on Moon's pole-facing slopes

ENERGY TECH
How Can We Protect Mars From Earth, While Searching For Life

The Search For Volcanic Eruptions On Mars Reaches The Next Level

Using Curiosity to Search for Life

Curiosity Self-Portrait at 'Mojave' Site on Mount Sharp

ENERGY TECH
Water pools in US astronaut's helmet after spacewalk

Korean tech start-ups offer life beyond Samsung

Fast visas and dim sum: Spain seeks to attract Chinese tourists

Industry: Risk aversion costs more than 'fast failure'

ENERGY TECH
More Astronauts for China

China launches the FY-2 08 meteorological satellite successfully

China's Long March puts satellite in orbit on 200th launch

Countdown to China's new space programs begins

ENERGY TECH
Russia to use International Space Station till 2024

NASA preparing to reassemble International Space Station

Spacewalking 'cable guys' wrap up work outside station

Space Station 3-D Printed Items, Seedlings Return in the Belly of a Dragon

ENERGY TECH
Soyuz Installed at Baikonur, Expected to Launch Wednesday

Leaders share messages, priorities at AFA Symposium

Moog offers "SoftRide" for enhanced spacecraft protection during launch

Russian-Ukrainian Satan Rocket to Launch South Korean Satellite as Planned

ENERGY TECH
The mystery of cosmic oceans and dunes

Laser 'ruler' holds promise for hunting exoplanets

Scientists predict earth-like planets around most stars

"Vulcan Planets" - Inside-Out Formation of Super-Earths

ENERGY TECH
Japan's NTT to buy German data centre operator: report

Moving molecule writes letters

New filter could advance terahertz data transmission

A simple way to make and reconfigure complex emulsions




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.