A nanoscale glimpse of batteries in action

September 13, 2013
Figure 1: High-resolution microscopy reveals that lithium–oxygen (Li–O2) batteries discharge power through a series of nanoscale product growth processes on atomically flat HOPG surfaces. Credit: 2013 American Chemical Society

Lithium–oxygen (Li–O2) batteries are a new type of experimental battery that electric car manufacturers are hoping will address the issue of limited driving range. Unlike the lithium-ion batteries used today, lithium–oxygen batteries do not require metal oxide cathodes to produce electrochemical power, instead generating power from reactions with oxygen in the atmosphere.

The significant weight savings realized through this design could potentially boost of batteries by up to four times. However, lithium–oxygen batteries have yet to leave the laboratory due to short battery lifespans caused by parasitic side reactions and accumulated charge polarization at battery cathodes.

Hye Ryung Byon with colleagues Rui Wen and Misun Hong from the RIKEN Byon Initiative Research Unit have now captured never-before-seen details of lithium–oxygen reactions using in situ (AFM) as a step toward resolving these drawbacks.

Byon and her colleagues set out to gather unambiguous evidence of nucleation, growth and decomposition of lithium–oxygen electrochemical products using AFM to trace out surface topographies down to nanometer scales. In their study, they crafted a comprised of a highly oriented pyrolytic graphite (HOPG) working electrode, metallic lithium counter and reference electrodes, and an ether-based solvent packed with oxygen gas and lithium salts as an electrolyte.

As lithium–oxygen batteries discharge power, lithium ions react with oxygen to produce solid lithium peroxide (Li2O2) deposits on atomically flat HOPG substrates. When the team monitored this reaction by AFM, they saw tiny particulates less than 10 nanometers high begin to nucleate along the 'step edges' inherent to HOPG (Fig. 1). These nanoparticles swiftly grew into elongated 'nanoplate' structures of micrometers in length, and further reaction caused the nanoplates themselves to fuse into a new lithium peroxide film.

The researchers then observed the battery recharge process, where oxygen gas is released and lithium ions migrate to the metallic lithium electrodes. Their AFM images revealed that during the initial recharge cycle, the lithium peroxide film decomposes completely, leaving no residue on the HOPG. By the fifth cycle, however, many by-products emerged as a result of the oxidation of the HOPG electrode and degradation of the ether-based electrolyte and lithium salt.

Byon notes that these findings will help researchers accurately correlate parameters such as electrode composition and size with changes in battery performance. "This could provide insight into the design of catalysts and electrodes for –oxygen batteries," she says.

Explore further: New lithium ion battery strategy offers more energy, longer life cycle

More information: Wen, R., Hong, M. & Byon, H. R. In situ AFM imaging of Li–O2 electrochemical reaction on highly oriented pyrolytic graphite with ether-based electrolyte, Journal of the American Chemical Society 135, 10870–10876 (2013). DOI: 10.1021/ja405188g

Related Stories

Progress made in building rechargeable lithium-air battery

July 20, 2012

(Phys.org) -- Researchers in the United Kingdom have taken another step towards proving that so named lithium-air (Li-O2) batteries might one day become practical. Up to now the problem has been using the technology to build ...

Team observes real-time charging of a lithium-air battery

May 13, 2013

One of the most promising new kinds of battery to power electric cars is called a lithium-air battery, which could store up to four times as much energy per pound as today's best lithium-ion batteries. But progress has been ...

High-efficiency zinc-air battery developed

May 29, 2013

Stanford University scientists have developed an advanced zinc-air battery with higher catalytic activity and durability than similar batteries made with costly platinum and iridium catalysts. The results, published in the ...

For better batteries, just add water

July 4, 2013

Lithium-ion batteries are now found everywhere in devices such as cellular phones and laptop computers, where they perform well. In automotive applications, however, engineers face the challenge of squeezing enough lithium-ion ...

Eavesdropping on lithium ions

July 8, 2013

(Phys.org) —Lithium ion batteries are at the energetic heart of almost all things tech, from cell phones to tablets to electric vehicles. That's because they are a proven technology, light, long-lasting and powerful. But ...

Recommended for you

Organic semiconductors get weird at the edge

October 6, 2015

As the push for tinier and faster electronics continues, a new finding by scientists at the University of British Columbia (UBC) and Monash University could help inform the design of the next generation of cheaper, more efficient ...

New polymer creates safer fuels

October 1, 2015

Before embarking on a transcontinental journey, jet airplanes fill up with tens of thousands of gallons of fuel. In the event of a crash, such large quantities of fuel increase the severity of an explosion upon impact. Researchers ...

Researchers print inside gels to create unique shapes

September 30, 2015

(Phys.org)—A team of researchers at the University of Florida has taken the technique of printing objects inside of a gel a step further by using a highly shear-rate sensitive gel. In their paper published in the journal ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.