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




ENERGY TECH
Dendrite eraser: New electrolyte rids batteries of short-circuiting fibers
by Staff Writers
Richland WA (SPX) Feb 25, 2015


Pacific Northwest National Laboratory has developed a new electrolyte that allows lithium-sulfur, lithium-metal and lithium-air batteries to operate well without growing dendrites, tiny pin-like fibers that short-circuit rechargeable batteries. Shown here are two scanning electron microscope images that illustrate how a traditional electrolyte can cause dendrite growth (a, left), while PNNL's new electrolyte instead causes the growth of smooth nodules that don't short-circuit batteries (b, right). Image courtesy PNNL.

Dendrites - the microscopic, pin-like fibers that cause rechargeable batteries to short circuit - create fire hazards and can limit the ability of batteries to power our smart phones and store renewable energy for a rainy day.

Now a new electrolyte for lithium batteries that's described in Nature Communications eliminates dendrites while also enabling batteries to be highly efficient and carry a large amount of electric current. Batteries using other dendrite-limiting solutions haven't been able to maintain both high efficiencies and current densities.

"Our new electrolyte helps lithium batteries be more than 99 percent efficient and enables them to carry more than ten times more electric current per area than previous technologies," said physicist Ji-Guang "Jason" Zhang of the Department of Energy's Pacific Northwest National Laboratory. "This new discovery could kick-start the development of powerful and practical next-generation rechargeable batteries such as lithium-sulfur, lithium-air and lithium-metal batteries."

Battery 101
Most of the rechargeable batteries used today are lithium-ion batteries, which have two electrodes: one that's positively charged and contains lithium and another, negative one that's typically made of graphite.

Electricity is generated when electrons flow through a wire that connects the two. To control the electrons, positively charged lithium atoms shuffle from one electrode to the other through another path: the electrolyte solution in which the electrodes sit. But graphite has a low energy storage capacity, limiting the amount of energy a lithium-ion battery can provide smart phones and electric vehicles.

When lithium-based rechargeable batteries were first developed in the 1970s, researchers used lithium for the negative electrode, which is also known as an anode. Lithium was chosen because it has ten times more energy storage capacity than graphite. Problem was, the lithium-carrying electrolyte reacted with the lithium anode. This caused microscopic lithium dendrites to grow and led the early batteries to fail.

Many have tweaked rechargeable batteries over the years in an attempt to resolve the dendrite problem. In the early 1990s, researchers switched to other materials such as graphite for the anode. More recently, scientists have also coated the anode with a protective layer, while others have created electrolyte additives. Some solutions eliminated dendrites, but also resulted in impractical batteries with little power. Other methods only slowed, but didn't stop, the fiber's growth.

Concentrated secret sauce
Thinking today's rechargeable lithium-ion batteries with graphite anodes could be near their peak energy capacity, PNNL is taking another look at the older designs. Zhang and his team sought to develop an electrolyte that worked well in batteries with a high-capacity lithium anode.

They noted others had some success with electrolytes with high salt concentrations and decided to use large amounts of the lithium bis(fluorosulfonyl)imide salt they were considering. To make the electrolyte, they added the salt to a solvent called dimethoxyethane.

The researchers built a circular test cell that was slightly smaller than a quarter. The cell used the new electrolyte and a lithium anode. Instead of growing dendrites, the anode developed a thin, relatively smooth layer of lithium nodules that didn't short-circuit the battery.

After 1,000 repeated charge and discharge cycles, the test cell retained a remarkable 98.4 percent of its initial energy while carrying 4 milliAmps of electrical current per square centimeter of area.

They found greater current densities resulted in slightly lower efficiencies. For example, a current density as high as 10 milliAmps per square centimeter, the test cell maintained an efficiency of more than 97 percent. And a test cell carrying just 0.2 milliAmps per square centimeter achieved a whopping 99.1 percent efficiency. Most batteries with lithium anodes operate at a current density of 1 milliAmps per square centimeter or less and fail after less than 300 cycles.

Anode-free battery?
The new electrolyte's remarkably high efficiency could also open the door for an anode-free battery, Zhang noted. The negative electrodes in today's batteries actually consist of thin pieces of metal such as copper that are coated in active materials such as graphite or lithium. The thin metal bases are called current collectors, as they are what keep electrons flowing to power our cell phones.

Active materials have been needed to coat the electrodes because, so far, most electrolytes have been inefficient and continue to consume lithium ions during battery operation. But an electrolyte with more than 99 percent efficiency means there's potential to create a battery that only has a negative current collector, without an active material coating, on the anode side.

"Not needing an anode could lower the cost and size of rechargeable batteries and would also significantly improve the safety of these batteries," Zhang said.

The electrolyte needs to be refined before it's ready for mainstream use, however. Zhang and his colleagues are evaluating various additives to further enhance their electrolyte so a lithium battery using it could achieve more than 99.9 percent efficiency, a level that's needed for commercial adoption. They are also examining which cathode materials would work best in combination with their new electrolyte.


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
Corvus Energy orders two new battery hybrid LNG ferry systems
Richmond, Canada (SPX) Feb 20, 2015
Corvus Energy, Elkon Electric (an Imtech Marine company) and Seaspan Ferries Corporation announced the award of the energy storage system (ESS) contract for two battery hybrid LNG ferries to be built at the Turkish shipyard Sedef Shipbuilding Inc., and designed by VARD Marine Inc. The new vessels will each use a 1050VDC, 546kWh Energy Storage System (ESS) consisting of 84 Corvus Energy AT6 ... 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
The highest plume ever observed on Mars

Mystery Mars plume baffles scientists

Up, Up and Away! First Humans Chosen for Mission to Mars

Mars One cuts list of potential colonists to 100

ENERGY TECH
Korean tech start-ups offer life beyond Samsung

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

Boeing's Space Efforts to Be Managed by Newly Created Organization

The ISS Menu: Mayo, Espressos, Booze? Cosmonauts Reveal Their Secrets

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

Spacesuit woes haunt NASA ahead of crucial spacewalks

Russia Launches Fresh Fruit, Oxygen to Crew on ISS

Europe destroys last space truck to ISS

ENERGY TECH
Soyuz Installed at Baikonur, Expected to Launch Wednesday

Moog offers "SoftRide" for enhanced spacecraft protection during launch

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

SpaceX launches deep-space weather observatory

ENERGY TECH
Laser 'ruler' holds promise for hunting exoplanets

Scientists predict earth-like planets around most stars

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

Dawn ahead!

ENERGY TECH
Apple to invest 1.7bn euros in Ireland, Denmark data centres

How iron feels the heat

Researchers glimpse distortions in atomic structure of materials

Data-storage for eternity




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.