Featured Research

from universities, journals, and other organizations

Lithium-ion batteries: Phenomenon of 'lithium plating' during the charging process observed

Date:
September 3, 2014
Source:
Technische Universitaet Muenchen
Summary:
Lithium-ion batteries are seen as a solution for energy storage of the future and have become indispensable, especially in electromobility. However, when metallic lithium forms and deposits during charging it can lead to a reduced battery lifespan and even short-circuits. Scientists have now managed to peer into the inner workings of a battery without destroying it.

Lithium-ion batteries are seen as a solution for energy storage of the future.
Credit: Andreas Heddergott / TUM

Lithium-ion batteries are seen as a solution for energy storage of the future and have become indispensible, especially in electromobility. Their key advantage is that they are able to store large amounts of energy but are still comparatively light and compact. However, when metallic lithium forms and deposits during charging it can lead to a reduced battery lifespan and even short-circuits. Scientists at the Technische Universität München (TUM) have now managed to peer into the inner workings of a battery without destroying it. In the process, they have resolved the so-called lithium plating mystery.

Related Articles


Mobile phones, digital cameras, camcorders, notebooks: They all run on lithium-ion batteries. These are characterized by high energy densities while remaining small and light enough to be used in portable devices. "A lithium-ion battery can store three to four times the energy of a comparably sized nickel-cadmium battery," explains Dr. habil. Ralph Gilles, scientist at the Neutron Source Heinz Maier-Leibnitz (FRM II). Even temperature fluctuations and longer-term storage do not pose problems for lithium-ion batteries.

These advantages make lithium-ion batteries a key technology for electromobility. In the not too distant future, electric vehicles will be able to hold their own against liquid fuel-driven transport media -- also with regard to the accessible distance. This will require powerful, safe and fast-charging batteries.

Lithium plating can cause short-circuits

However, one previously known, yet poorly understood phenomenon stands in the way of this goal: metallic lithium deposition or lithium plating, as it is called.

Simply put, energy storage in a lithium-ion battery works by the following principle: Both the positive electrode (cathode) and the negative electrode (anode) can bind lithium ions. During the charging process, the induced electrical field forces the ions to move from the cathode to the anode. When the battery is discharged, the lithium ions move back to the cathode, releasing energy in the process.

The cathode in lithium-ion batteries comprises a lithium metal oxide while the standard material for battery anodes is graphite (carbon) with a layered structure. During the charging process, the lithium ions are stored in these layers.

However, occasionally lithium ions form metallic lithium instead of intercalating into the anode, as desired. The lithium deposits onto the anode and is no longer fully available for the described process. The result is a drop in battery performance. In extreme cases this can even lead to short-circuits. In addition, metallic lithium is highly inflammable.

Non-destructive investigation using neutrons as a probe

Hitherto, observing the precise mechanism at work during lithium plating has not been possible. When a battery is opened, explains Ralph Gilles, you only get a snapshot of its present state. Yet, the amount of metallic lithium changes permanently. Using neutron beams, the scientists Dr. Veronika Zinth at the Neutron Source Heinz Maier-Leibnitz (FRM II) and Christian von Lüders at the Department of Electrical Energy Storage Technology were able to observe the processes inside of batteries without cutting them open.

"In contrast to other methods, with neutron diffraction we can make more precise statements about when and how strongly lithium plating takes place," explains Veronika Zinth.

Using the material research diffractometer STRESS-SPEC at FRM II, the researchers installed a battery, in both charging and discharging states, into the neutron beam. The incident neutron beam is diffracted according to Bragg's law and collected in a detector. Using these signals, the researchers were able to indirectly deduce how much metallic lithium had formed.

Faster charging means more metallic lithium

Initial results of the study:

  • The faster the charging process, the more metallic lithium is formed. Up to 19 % of the lithium ions normally involved in the charging and discharging process take on the metallic form. (The measurements were made at -20 degrees Celsius).
  • During a 20-hour resting phase following a fast recharge some of the metallic lithium reacts with the graphite, intercalating between the graphite layers as lithium ions. It is effectively a delayed, slow charging process. Albeit, only a part of the lithium plating is reversible.
  • Low temperatures encourage the formation of metallic lithium.

The scientists are planning further experiments to shed more light on the lithium plating mechanism. The results may help answer the question of how the phenomenon might be averted altogether. This will also involve answering the question of how quickly batteries can be charged before lithium plating sets in.

The study is part of the German Federal Ministry of Education and Research (BMBF) ExZellTUM (Exellence Center for Battery Cells) project. The ExZellTUM project is geared towards the development of new energy storage systems, as well as new manufacturing processes, forming strategies and test technologies for storage systems production. The project comprises four partners: the Department of Electrical Energy Storage Systems, the Department of Machine Tools and Industrial Management, the Department of Technical Electrochemistry and the Neutron Source Heinz Maier-Leibnitz.


Story Source:

The above story is based on materials provided by Technische Universitaet Muenchen. Note: Materials may be edited for content and length.


Journal Reference:

  1. Veronika Zinth, Christian von Lüders, Michael Hofmann, Johannes Hattendorff, Irmgard Buchberger, Simon Erhard, Joana Rebelo-Kornmeier, Andreas Jossen, Ralph Gilles. Lithium plating in lithium-ion batteries at sub-ambient temperatures investigated by in situ neutron diffraction. Journal of Power Sources, 2014; 271: 152 DOI: 10.1016/j.jpowsour.2014.07.168

Cite This Page:

Technische Universitaet Muenchen. "Lithium-ion batteries: Phenomenon of 'lithium plating' during the charging process observed." ScienceDaily. ScienceDaily, 3 September 2014. <www.sciencedaily.com/releases/2014/09/140903105638.htm>.
Technische Universitaet Muenchen. (2014, September 3). Lithium-ion batteries: Phenomenon of 'lithium plating' during the charging process observed. ScienceDaily. Retrieved November 24, 2014 from www.sciencedaily.com/releases/2014/09/140903105638.htm
Technische Universitaet Muenchen. "Lithium-ion batteries: Phenomenon of 'lithium plating' during the charging process observed." ScienceDaily. www.sciencedaily.com/releases/2014/09/140903105638.htm (accessed November 24, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Monday, November 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Microsoft Adds Robot Guards, Ushers In Sci-Fi Apocalypse

Microsoft Adds Robot Guards, Ushers In Sci-Fi Apocalypse

Newsy (Nov. 23, 2014) — Microsoft has robotic security guards working at its Silicon Valley Campus. Video provided by Newsy
Powered by NewsLook.com
Toyota's Hydrogen Fuel-Cell Green Car Soon Available in the US

Toyota's Hydrogen Fuel-Cell Green Car Soon Available in the US

AFP (Nov. 21, 2014) — Toyota presented its hydrogen fuel-cell compact car called "Mirai" to US consumers at the Los Angeles auto show. The car should go on sale in 2015 for around $60.000. It combines stored hydrogen with oxygen to generate its own power. Duration: 01:18 Video provided by AFP
Powered by NewsLook.com
Google Announces Improvements To Balloon-Borne Wi-Fi Project

Google Announces Improvements To Balloon-Borne Wi-Fi Project

Newsy (Nov. 21, 2014) — In a blog post, Google said its balloons have traveled 3 million kilometers since the start of Project Loon. Video provided by Newsy
Powered by NewsLook.com
Raw: Paralyzed Marine Walks With Robotic Braces

Raw: Paralyzed Marine Walks With Robotic Braces

AP (Nov. 21, 2014) — Marine Corps officials say a special operations officer left paralyzed by a sniper's bullet in Afghanistan walked using robotic leg braces in a ceremony to award him a Bronze Star. (Nov. 21) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins