Fast calculation dials in better batteries
Analytical model helps researchers fine-tune battery performance

Date:
September 16, 2020
Source:
Rice University
Summary:
A simpler and more efficient way to predict the performance of
batteries will lead to better batteries, according to engineers.



FULL STORY ==========================================================================
A simpler and more efficient way to predict performance will lead to
better batteries, according to Rice University engineers.


==========================================================================
That their method is 100,000 times faster than current modeling techniques
is a nice bonus.

The analytical model developed by materials scientist Ming Tang and
graduate student Fan Wang of Rice University's Brown School of Engineering doesn't require complex numerical simulation to guide the selection and
design of battery components and how they interact.

The simplified model developed at Rice -- freely accessible online -- does
the heavy lifting with an accuracy within 10% of more computationally
intensive algorithms. Tang said it will allow researchers to quickly
evaluate the rate capability of batteries that power the planet.

The results appear in the open-access journal Cell Reports Physical
Science.

There was a clear need for the updated model, Tang said.



========================================================================== "Almost everyone who designs and optimizes battery cells uses a well- established approach called P2D (for pseudo-two dimensional) simulations,
which are expensive to run," Tang said. "This especially becomes a
problem if you want to optimize battery cells, because they have many
variables and parameters that need to be carefully tuned to maximize
the performance.

"What motivated this work is our realization that we need a faster, more transparent tool to accelerate the design process, and offer simple, clear insights that are not always easy to obtain from numerical simulations,"
he said.

Battery optimization generally involves what the paper calls a "perpetual trade-off" between energy (the amount it can store) and power density
(the rate of its release), all of which depends on the materials, their configurations and such internal structures as porosity.

"There are quite a few adjustable parameters associated with the structure
that you need to optimize," Tang said. "Typically, you need to make tens
of thousands of calculations and sometimes more to search the parameter
space and find the best combination. It's not impossible, but it takes
a really long time." He said the Rice model could be easily implemented
in such common software as MATLAB and Excel, and even on calculators.

To test the model, the researchers let it search for the optimal porosity
and thickness of an electrode in common full- and half-cell batteries. In
the process, they discovered that electrodes with "uniform reaction"
behavior such as nickel-manganese-cobalt and nickel-cobalt-aluminum oxide
are best for applications that require thick electrodes to increase the
energy density.

They also found that battery half-cells (with only one electrode) have inherently better rate capability, meaning their performance is not a
reliable indicator of how electrodes will perform in the full cells used
in commercial batteries.

The study is related to the Tang lab's attempts at understanding and
optimizing the relationship between microstructure and performance of
battery electrodes, the topic of several recent papers that showed how
defects in cathodes can speed lithium absorption and how lithium cells
can be pushed too far in the quest for speed.


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


========================================================================== Journal Reference:
1. Fan Wang, Ming Tang. A Quantitative Analytical Model for Predicting
and
Optimizing the Rate Performance of Battery Cells. Cell Reports
Physical Science, 2020; 100192 DOI: 10.1016/j.xcrp.2020.100192 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200916131029.htm

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