Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A simple way to make lithium-ion battery electrodes that protect themselves

11.01.2016

Surprising result could pave way to cheaper, higher capacity batteries

Scientists at three Department of Energy national laboratories have discovered how to keep a promising new type of lithium ion battery cathode from developing a crusty coating that degrades its performance. The solution: Use a simple manufacturing technique to form the cathode material into tiny, layered particles that store a lot of energy while protecting themselves from damage.


These are images of particles made from a promising battery cathode material called NMC. Scientists found a simple method for making layered NMC particles that store more energy while protecting themselves from degradation. The smallest particles, at bottom, are just 100 billionths of a meter in diameter; they clump into larger spherical particles, top. The color image at center shows the uneven distribution of chemical elements on a particle's surface, which is key to its improved performance. The black-and-white images were made with an electron microscope at Brookhaven National Laboratory; color images are based on X-ray studies at SLAC.

Credit: SLAC National Accelerator Laboratory

Test batteries that incorporated this cathode material held up much better when charged and discharged at the high voltages needed to fast-charge electric vehicles, the scientists report in a paper published Jan. 11 in the inaugural issue of Nature Energy.

"We were able to engineer the surface in a way that prevents rapid fading of the battery's capacity," said Yijin Liu, a staff scientist at SLAC National Accelerator Laboratory and a co-author of the report. The results are potentially significant because they pave the way for making lithium-ion batteries that are cheaper and have higher energy density.

Good Nickel, Bad Nickel

Chemistry is at the heart of all lithium-ion rechargeable batteries, which power portable electronics and electric cars by shuttling lithium ions between positive and negative electrodes bathed in an electrolyte solution. As lithium ions move into the cathode, chemical reactions generate electrons that can be routed to an external circuit for use. Recharging pulls lithium ions out of the cathode and sends them to the anode.

Cathodes made of nickel manganese cobalt oxide, or NMC, are an especially hot area of battery research because they can operate at the relatively high voltages needed to store a lot of energy in a very small space.

But while the nickel in NMC gives it a high capacity for storing energy, it's also reactive and unstable, with a tendency to undergo destructive side reactions with the electrolyte. Over time this forms a rock salt-like crust that blocks the flow of lithium ions, said study co-author Huolin Xin of Brookhaven National Laboratory.

In this study, the researchers experimented with ways to incorporate nickel but protect it from the electrolyte.

Particles that Protect Themselves

A team led by Marca Doeff at Lawrence Berkeley National Laboratory sprayed a solution of lithium, nickel, manganese and cobalt through an atomizer nozzle to form droplets that decomposed to form a powder. Repeatedly heating and cooling the powder triggered the formation of tiny particles that assembled themselves into larger, spherical and sometimes hollow structures.

This technique, called spray pyrolysis, is cheap, widely used and easily scaled up for commercial production. And in this case it did something unexpected. Like a cake batter that sorts itself into distinct layers during baking, the NMC particles emerged from the process with their basic ingredients redistributed.

The new structure became clear when the cathode particles were examined in detail at SLAC and Brookhaven. At SLAC's Stanford Synchrotron Radiation Lightsource, Liu and his colleagues used X-rays to probe the particles at a scale of 10-20 microns, or millionths of a meter. At Brookhaven's Center for Functional Nanomaterials, Xin and his team used a scanning transmission electron microscope to zoom in on details as small as billionths of a meter, a realm known as the nanoscale. A Simple Road to Higher Capacity

With both techniques and at every scale they looked, the particles had a different structure than the original starting material. When the SSRL team looked at tiny 3-D areas within the material, for instance, only 70 percent of them contained all three of the starting metals - nickel, manganese and cobalt.

"The particles have more nickel on the inside, to store more energy, and less on the surface, where it would cause problems," Liu said. At the same time, the surface of the particles was enriched in manganese, which acted like a coat of paint to protect the interior.

"We're not the first ones who have come up with idea of decreasing nickel on the surface. But we were able to do it in one step using a very simple procedure," Doeff said. "We still want to increase the nickel content even further, and this gives us a possible avenue for doing that. The more nickel you have, the more practical capacity you may have at voltages that are practical to use."

In future experiments, the researchers plan to probe the NMC cathode with X-rays while it's charging and discharging to see how its structure and chemistry change. They also hope to improve the material's safety: As a metal oxide, it could release oxygen during operation and potentially cause a fire.

"To make a real, functional battery that can be commercialized, you have to look beyond performance," Liu said. "Safety and many other things have to be considered."

###

Other researchers who contributed to this work were lead author Feng Lin and Matthew Quan of Berkeley Lab; Dennis Nordlund and Tsu-Chien Weng of SLAC; and Lei Cheng of Berkeley Lab and the University of California, Berkeley. This work was supported by DOE's Vehicle Technologies Office. SLAC's Stanford Synchrotron Radiation Lightsource and Brookhaven's Center for Functional Nanomaterials are DOE Office of Science User Facilities.

Portions of this press release were based on press releases from Lawrence Berkeley National Laboratory and Brookhaven National Laboratory.

Citation: F. Lin et al., Nature Energy, 11 January 2016, (0.1038/nenergy.2015.4)

SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the U.S. Department of Energy Office of Science. To learn more, please visit http://www.slac.stanford.edu.

SLAC National Accelerator Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

Media Contact

Andrew Gordon
agordon@slac.stanford.edu
650-926-2282

 @SLAClab

http://www.slac.stanford.edu 

Andrew Gordon | EurekAlert!

More articles from Materials Sciences:

nachricht Manchester scientists tie the tightest knot ever achieved
13.01.2017 | University of Manchester

nachricht CWRU directly measures how perovskite solar films efficiently convert light to power
12.01.2017 | Case Western Reserve University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

Im Focus: Newly proposed reference datasets improve weather satellite data quality

UMD, NOAA collaboration demonstrates suitability of in-orbit datasets for weather satellite calibration

"Traffic and weather, together on the hour!" blasts your local radio station, while your smartphone knows the weather halfway across the world. A network of...

Im Focus: Repairing defects in fiber-reinforced plastics more efficiently

Fiber-reinforced plastics (FRP) are frequently used in the aeronautic and automobile industry. However, the repair of workpieces made of these composite materials is often less profitable than exchanging the part. In order to increase the lifetime of FRP parts and to make them more eco-efficient, the Laser Zentrum Hannover e.V. (LZH) and the Apodius GmbH want to combine a new measuring device for fiber layer orientation with an innovative laser-based repair process.

Defects in FRP pieces may be production or operation-related. Whether or not repair is cost-effective depends on the geometry of the defective area, the tools...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Multiregional brain on a chip

16.01.2017 | Power and Electrical Engineering

New technology enables 5-D imaging in live animals, humans

16.01.2017 | Information Technology

Researchers develop environmentally friendly soy air filter

16.01.2017 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>