Welcome back everyone, I'm Jordan Giesige
and this is The Limiting Factor. Today
we're gonna be talking about Jeff Dahn
from Dalhousie University. Jeff is a
giant in the battery world. He pioneered
technology that shortens the testing of
batteries by up to eight years and he's
now partnered with Tesla. Tesla is
working on a million-mile battery with
Jeff Dahn. This is critical for Tesla's
success because it will allow them to
dominate fossil fuel based industries
such as the automobile and electricity
generation. Jeff has been working on
batteries since 1979 and he helped
pioneer the lithium-ion battery. He's the
author of over 640 refereed journal
papers and about 5,400 papers cite his
work each year. Jeff is most widely known
for inventing the NMC chemistry for
battery cathodes which is one of the
most widely used lithium-ion chemistry's
in the world today and is produced at a
rate of six thousand metric tons per
year. Meaning that one in ten lithium-ion
batteries are using his chemistry. In
2008 Jeff and his team pioneered battery
testing equipment that speeds the
development of batteries by orders of
magnitude. Testing that used to take
years they can do in weeks. This was done
by creating testing equipment that could
measure Coulombic efficiency at a
high degree of precision. Let's talk
about what columbic efficiency is and
how it measures the speed that batteries
degrade. High coulombic efficiency means
that you get all of the energy back out
of a cell that you put into it. When you
don't get all the energy back out of a
cell that you put into it, where is that
energy going? It's going to unwanted
reactions that break down the battery. So,
Coulombic efficiency helps predict when a
battery will fail. High precision is
required because that's the only way to
predict how a cell will perform years in
advance. For example, if a battery has a
coulombic efficiency of 0.99 or 99%, that
means one percent of the energy is going
to unwanted reactions that damage the
cell. That means the battery will lose
about 40 percent of its life by 50
cycles. A typical battery today has a
coulombic efficiency of 99.9 percent. So,
the battery loses about
40% of its life by 500 cycles - which is a
few years. To reach a million mile
battery Tesla will need four thousand
cycles. In other words, they'll need
another order of magnitude greater
coulombic efficiency than a typical
battery.
They'll need 99.99%. This battery would
last decades. If Jeff Don creates this
battery with Tesla, it will be a defining
achievement. For reference,
Tesla batteries already have a coulombic
efficiency of around ninety nine point
nine five percent and the potential to
last up to two thousand cycles, which is
already way ahead of the competition.
Moving forward to 2015,
Jeff saw what Tesla was doing with the
gigafactory and approached Tesla because
he said he had to be part of what they
are doing. In 2016, he ended his 20-year
partnership with 3M and entered into a
five-year agreement with Tesla. Since
then, we've seen Jeff's team publish
several papers and register patents for
approaches to solving the 1 million mile
battery problem through better battery
chemistry and single crystal cathode
material. I don't think Jeff is sharing
everything yet. As Elon said their secret
sauce will be revealed at the battery
investor day sometime in the next few
months. For the science nerds we're now
going to take a closer look at Jeff's
setup, test results, and how they compare
to industry standard methods of
evaluating batteries. This is a bank of
100 high-precision coulometry machines
that charge and discharge batteries at a
constant temperature.
The precision level they measure to is 5
decimal places. The equivalent would be
the ability to consistently weigh a
hundred kg or 220 pound person to one
gram. And finally, here is an example of
the results. In the upper right is the
testing Jeff and his team do. The graph
is showing 0 to 16 cycles and a
coulombic efficiency of 0.996 to 1 - the
higher the better.
Notice that we're only talking about a
difference of .002, which
is 0.2%, between the best-performing cell
(which is a triangle) and the
worst-performing cell (which is a plus). If
you look at the graph in the center
bottom we can see a typical testing
process showing 0 to 600 cycles. Again,
the best-performing is the triangle and
the worst is the plus, which is what
Jeff's measurements had already predicted by 16 cycles. This is the power of
his testing method and also shows the
power of exponential change over time. A
point two percent decrease in coulombic efficiency means about a 70
percent decrease in battery life. For
long life batteries, some of these tests
run for eight years.
Think about that. Thousands of cycles and
eight years of testing to find out how
one cell chemistry works.
Jeff's lab can do it in a few weeks. So,
in short, if Tesla's goal is to
accelerate the world's transition to
sustainable energy,
Jeff Dahn is one of Tesla's secret
weapons. His lab is helping place them
perhaps years ahead of the competition.
Elon is gathering the best and brightest
in many different technologies and the
result is clear. Tesla is crushing the
competition, without even a distant
second. Well, I hope you enjoyed watching
that as much as I did making it. In the
next video we're going to be talking
about Shirley Meng from the University
of California San Diego.
Shirley's lab specializes in
characterization and modeling.
Characterization is looking into a
battery cell to find out what's actually
going on, sometimes even in real time.
Modeling is using AI and big data to try
to predict which materials will make the
best batteries. I'm Jordan Giesige, this
is The Limiting Factor, and thanks for
tuning in.
