Speed and absorption key to optimizing new type of rechargeable battery


Date:
August 10, 2021
Source:
Okinawa Institute of Science and Technology (OIST) Graduate
University
Summary:
Rechargeable, lithium sulfur batteries are promising candidates
to sustainably meet the world's energy demands, and a new study
has put them one step closer to becoming readily available.



FULL STORY ========================================================================== Rechargeable batteries are a necessity to meet the world's growing energy demands in a sustainable fashion but not all are equal. Researchers
in the Energy Materials and Surface Sciences Unit at the Okinawa
Institute of Science and Technology Graduate University have worked to
optimize a promising candidate of such energy sources -- lithium sulfur batteries. The study was published today in Nature Communications.


========================================================================== "Lithium sulfur batteries can store more energy than the lithium ion
batteries that are already commercially available," said Dr. Hui Zhang,
first author of this study. "To put this in numbers, an electric vehicle
that runs on lithium ion batteries can drive an average of 300km before
it needs to be charged. With the improved energy storage provided by
lithium sulfur batteries, it should be possible to extend this to 500km."
The main challenge that has prevented lithium sulfur batteries from
becoming commercialized is that the intermediate product is susceptible
to dissolving.

During the construction of the battery, the sulfur will react with the
lithium to form a product. There are two stages to this. In the first
stage, the product will be lithium polysulfide, which can easily dissolve
into polysulfides. If this happens, the polysulfides will impair the performance of the battery, resulting in its lifespan being greatly
reduced. To optimize the batteries, the lithium polysulfide needs to
transform to the final product, either Li2S2 or Li2S, as quickly as
possible. To do this, the researchers utilized two different materials --
TiO2, which absorbs the unwanted polysulfides, and TiN, which accelerates
the process.

"Using these two materials, we developed a hybrid that is low cost and
easy to apply," said Dr. Luis Ono, second author of this study. "We found
that it had an excellent ability to improve the battery performance."
These materials are very sensitive. To maximize the battery's efficiency,
the researchers worked on the scale of nanometers. They found that 10nm
of TiN and 5nm of TiO2 created the most efficient product. With the polysulfides being absorbed and the whole process being accelerated,
the batteries performance was greatly improved. This translated to a
shorter charging time, a longer life between charges, and a greater
overall lifespan. To establish this, the researchers ran the battery
for 200 cycles and found that its efficiency was almost the same.

"We will continue to further optimize the materials to improve the performance," said Professor Yabing Qi, senior author of the study and
head of the Energy Materials and Surface Sciences Unit at OIST. "There
are a lot of brilliant minds working on lithium sulfur batteries and
it's a really promising and exciting technology." In summary:
* High quality, rechargeable batteries are a necessity to sustainably
meet
the world's growing energy demands.

* Lithium sulfur batteries are promising candidates for the next
generation
of these energy sources as they can store more energy than other
rechargeable batteries.

* For lithium sulfur batteries to become readily available, a common,
dissolving issue during their construction needs to be overcome.

* The researchers created a hybrid material that both accelerates the
construction process, which reduced the likelihood of the issue
occurring, and absorbs any unwanted products that may have been
produced in the process.

* The result was a lithium sulfur battery that had a longer life span,
required a shorter charging time, and could run for more time
between charges.

This study received support from the OIST Technology Development and
Innovation Center's Proof-of-Concept Program.

========================================================================== Story Source: Materials provided by Okinawa_Institute_of_Science_and_Technology_(OIST)
Graduate_University. Original written by Lucy Dickie. Note: Content may
be edited for style and length.


========================================================================== Journal Reference:
1. Hui Zhang, Luis K. Ono, Guoqing Tong, Yuqiang Liu, Yabing
Qi. Long-life
lithium-sulfur batteries with high areal capacity based on coaxial
CNTs@TiN-TiO2 sponge. Nature Communications, 2021; 12 (1) DOI:
10.1038/ s41467-021-24976-y ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210810104702.htm

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