Decades-old mystery of lithium-ion battery storage solved

Date:
September 2, 2020
Source:
University of Texas at Austin
Summary:
For years, researchers have aimed to learn more about a group
of metal oxides that show promise as key materials for the next
generation of lithium-ion batteries because of their mysterious
ability to store significantly more energy than should be
possible. An international research team has now cracked the code
of this scientific anomaly, knocking down a barrier to building
ultra-fast battery energy storage systems.



FULL STORY ==========================================================================
For years, researchers have aimed to learn more about a group of metal
oxides that show promise as key materials for the next generation of lithium-ion batteries because of their mysterious ability to store significantly more energy than should be possible. An international
research team, co-led by The University of Texas at Austin, has cracked
the code of this scientific anomaly, knocking down a barrier to building ultra-fast battery energy storage systems.


==========================================================================
The team found that these metal oxides possess unique ways to store
energy beyond classic electrochemical storage mechanisms. The research, published in Nature Materials, found several types of metal compounds
with up to three times the energy storage capability compared with
materials common in today's commercially available lithium-ion batteries.

By decoding this mystery, the researchers are helping unlock batteries
with greater energy capacity. That could mean smaller, more powerful
batteries able to rapidly deliver charges for everything from smartphones
to electric vehicles.

"For nearly two decades, the research community has been perplexed by
these materials' anomalously high capacities beyond their theoretical
limits," said Guihua Yu, an associate professor in the Walker Department
of Mechanical Engineering at the Cockrell School of Engineering and one
of the leaders of the project. "This work demonstrates the very first experimental evidence to show the extra charge is stored physically inside these materials via space charge storage mechanism." To demonstrate this phenomenon, the team found a way to monitor and measure how the elements
change over time. Researchers from UT, the Massachusetts Institute of Technology, the University of Waterloo in Canada, Shandong University of
China, Qingdao University in China and the Chinese Academy of Sciences participated in the project.

At the center of the discovery are transition-metal oxides, which are
compounds that include oxygen bonded with transition metals such as
iron, nickel and zinc. Energy can be stored inside the metal oxides -- as opposed to typical methods that see lithium ions move in and out of these materials or convert their crystal structures for energy storage. And the researchers show that additional charge capacity can also be stored at
the surface of iron nanoparticles formed during a series of conventional electrochemical processes.

A broad range of transition metals can unlock this extra capacity,
according to the research, and they share a common thread -- the ability
to collect a high density of electrons. These materials aren't yet ready
for prime time, Yu said, primarily because of a lack of knowledge about
them. But the researchers said these new findings should go a long way
in shedding light on the potential of these materials.

The key technique employed in this study, named in situ magnetometry,
is a real-time magnetic monitoring method to investigate the evolution
of a material's internal electronic structure. It is able to quantify
the charge capacity by measuring variations in magnetism. This technique
can be used to study charge storage at a very small scale that is beyond
the capabilities of many conventional characterization tools.

"The most significant results were obtained from a technique commonly
used by physicists but very rarely in the battery community," Yu
said. "This is a perfect showcase of a beautiful marriage of physics
and electrochemistry."

========================================================================== Story Source: Materials provided by University_of_Texas_at_Austin. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Qiang Li, Hongsen Li, Qingtao Xia, Zhengqiang Hu, Yue Zhu,
Shishen Yan,
Chen Ge, Qinghua Zhang, Xiaoxiong Wang, Xiantao Shang, Shuting
Fan, Yunze Long, Lin Gu, Guo-Xing Miao, Guihua Yu, Jagadeesh
S. Moodera. Extra storage capacity in transition metal oxide
lithium-ion batteries revealed by in situ magnetometry. Nature
Materials, 2020; DOI: 10.1038/s41563-020- 0756-y ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200902095138.htm

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