Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Tweaking electrolyte makes better lithium-metal batteries

02.03.2017

A pinch of electrolyte additive gives rechargeable battery stability, longer life

Scientists have found adding a pinch of something new to a battery's electrolyte gives the energy storage devices more juice per charge than today's commonly used rechargeable batteries.


This is an artist's illustration shows how PNNL's addition of the chemical lithium hexafluorophosphate to a dual-salt, carbonate solvent-based electrolyte makes rechargeable lithium-metal batteries stable, charge quickly, have a high voltage, and go longer in between charges.

Credit: Pacific Northwest National Laboratory

New, early-stage research shows adding a small amount of the chemical lithium hexafluorophosphate to a dual-salt, carbonate solvent-based electrolyte can make rechargeable lithium-metal batteries stable, charge quickly and have a high voltage.

"A good lithium-metal battery will have the same lifespan as the lithium-ion batteries that power today's electric cars and consumer electric devices, but also store more energy so we can drive longer in between charges," said chemist Wu Xu of the Department of Energy's Pacific Northwest National Laboratory. Xu is a corresponding author on a paper published today in the journal Nature Energy.

Battery basics

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 shuttle from one electrode to the other through another path, the electrolyte solution in which the electrodes sit. But graphite can't store much energy, 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 metal for the negative electrode, called 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 nanoparticles and branches called dendrites to grow on the anode surface, and led the early batteries to fail.

Many have tweaked rechargeable batteries over the years in an attempt to resolve the dendrite problem. Researchers switched to other materials such as graphite for the anode. Scientists have also coated anodes with protective layers, 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, dendrite growth.

Next-generation storage

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 design with lithium metal as an anode. Xu and colleagues were part of earlier PNNL research seeking a better-performing electrolyte. The electrolytes they tried produced either a battery that didn't have problematic dendrites and was super-efficient but charged very slowly and couldn't work in higher-voltage batteries, or a faster-charging battery that was unstable and had low voltages.

Next, they tried adding small amounts of a salt that's already used in lithium-ion batteries, lithium hexafluorophosphate, to their fast-charging electrolyte. They paired the newly juiced-up electrolyte with a lithium anode and a lithium nickel manganese cobalt oxide cathode. It turned out to be a winning combination, resulting in a fast, efficient, high-voltage battery.

The additive enabled a 4.3-volt battery that retained more than 97 percent of its initial charge after 500 repeated charges and discharges, while carrying 1.75 milliAmps of electrical current per square centimeter of area. It took the battery about one hour to fully charge.

Inexpensive protection

The battery performed well largely because the additive helps create a robust protective layer of carbonate polymers on the battery's lithium anode. This thin layer prevents lithium from being used up in unwanted side reactions, which can kill a battery.

And, because the additive is already an established component of lithium-ion batteries, it's readily available and relatively inexpensive. The small amounts needed - just 0. 6 percent of the electrolyte by weight - should also further lower the electrolyte's cost.

Xu and his team continue to evaluate several ways to make rechargeable lithium-metal batteries viable, including improving electrodes, separators and electrolytes. Specific next steps include making and testing larger quantities of their electrolyte, further improving the efficiency and capacity retention of a lithium-metal battery using their electrolyte, increasing material loading on the cathode and trying a thinner anode.

###

This research was supported by the Department of Energy's Office of Energy Efficiency and Renewable Energy. Researchers performed microscopy and spectroscopy characterizations of battery materials at EMSL, the Environmental Molecular Sciences Laboratory, a DOE Office of Science national User Facility at PNNL. The battery electrodes were made at DOE's Cell Analysis, Modeling, and Prototyping Facility at Argonne National Laboratory.

REFERENCE: Jianming Zheng, Mark H. Engelhard, Donghai Mei, Shuhong Jiao, Bryant J. Polzin, Ji-Guang Zhang & Wu Xu, "Electrolyte Additive Enabled Fast Charging and Stable Cycling Lithium Metal Batteries," Nature Energy, DOI: 10.1038/nenergy.2017.12, March 1, 2017, http://www.nature.com/articles/nenergy201712.

EMSL, the Environmental Molecular Sciences Laboratory, is a DOE Office of Science User Facility. Located at Pacific Northwest National Laboratory in Richland, Wash., EMSL offers an open, collaborative environment for scientific discovery to researchers around the world. Its integrated computational and experimental resources enable researchers to realize important scientific insights and create new technologies. Follow EMSL on Facebook, LinkedIn and Twitter.

Interdisciplinary teams at Pacific Northwest National Laboratory address many of America's most pressing issues in energy, the environment and national security through advances in basic and applied science. Founded in 1965, PNNL employs 4,400 staff and has an annual budget of nearly $1 billion. It is managed by Battelle for the U.S. Department of Energy's Office of Science. As the single largest supporter of basic research in the physical sciences in the United States, the Office of Science is working to address some of the most pressing challenges of our time. For more information on PNNL, visit the PNNL News Center, or follow PNNL on Facebook, Google+, Instagram, LinkedIn and Twitter.

Media Contact

Franny White
franny.white@pnnl.gov
509-375-6904

 @PNNLab

http://www.pnnl.gov/news

Franny White | EurekAlert!

More articles from Power and Electrical Engineering:

nachricht A water-based, rechargeable battery
09.01.2018 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt

nachricht To jump or not to jump
09.01.2018 | Max-Planck-Institut für Dynamik und Selbstorganisation

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

Im Focus: A thermometer for the oceans

Measurement of noble gases in Antarctic ice cores

The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...

Im Focus: Autoimmune Reaction Successfully Halted in Early Stage Islet Autoimmunity

Scientists at Helmholtz Zentrum München have discovered a mechanism that amplifies the autoimmune reaction in an early stage of pancreatic islet autoimmunity prior to the progression to clinical type 1 diabetes. If the researchers blocked the corresponding molecules, the immune system was significantly less active. The study was conducted under the auspices of the German Center for Diabetes Research (DZD) and was published in the journal ‘Science Translational Medicine’.

Type 1 diabetes is the most common metabolic disease in childhood and adolescence. In this disease, the body's own immune system attacks and destroys the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fachtagung analytica conference 2018

15.01.2018 | Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

 
Latest News

Black hole spin cranks-up radio volume

15.01.2018 | Physics and Astronomy

A matter of mobility: multidisciplinary paper suggests new strategy for drug discovery

15.01.2018 | Life Sciences

New method to map miniature brain circuits

15.01.2018 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>