Welcome back everyone! I’m Jordan Giesige and this is The Limiting
Factor. Lithium Iron Phosphate, or LFP, batteries
are quickly gaining momentum in the race to electrify transport and the grid. A little over a year ago, LFP wasn’t on
most peoples’ radar and was considered a second best chemistry compared to the High
Nickel chemistries that most western auto makers, including Tesla, were using. This all changed when Tesla started using
LFP batteries for the Standard Range Plus Model 3 in China and announced on battery
day that they’d be manufacturing LFP battery cells. Now, Elon is saying that eventually, Lithium
Ion batteries using Iron will exceed those using Nickel by 3:1 or more. For Tesla customers and investors, this begs
the question: What are the advantages and disadvantages of LFP batteries and what’s
the basic science behind them? Today I’ll compare a standard LFP Chemistry
like CATL’s to the NCA chemistry produced by Panasonic at Giga Nevada for Tesla. For those looking for information on the BYD
blade battery and Tesla’s 4680 with LFP, those will each be covered in separate videos. This video mainly focuses on chemistry, whereas
the Blade and 4680 are mainly form factor changes that come with a host of additional
benefits. Before we begin, a special thanks to my Patreon
supporters and YouTube members. This is the support that gives me the freedom
to avoid chasing the algorithm and sponsors, and I hope will eventually allow me to do
this full time. As always, the links for support are in the
description. For this video, I’d also like to thank Matt
Lacey and Battery Bulletin for answering my many questions on LFP. Without those insights, this video wouldn’t
have been possible. The two primary active components of a lithium
ion battery are the cathode and anode. The anode is usually made of graphite, which
is shown here on the left by the potato shaped particles. The cathode is on the right and is shown by
the spherical particles. The spherical cathode particles usually come
in two different flavours, iron or nickel dominant. Let’s take a look at the atomic level. The crystal marked with Fe in pink is our
LFP cathode crystal. Fe just stands for ferro, which is Latin for
iron. The crystal marked with Ni in pink is our
Nickel cathode crystal. We’ll call this crystal NCA because Tesla
dopes their Nickel or N, with a dash of cobalt and aluminum, CA. All the differences that we’ll explore today
between LFP and NCA result from the difference in these two crystal structures. And what do we see? In LFP, the lithium is the grey spheres, the
phosphate is the red triangles, and the iron is the blue octahedra. The lithium is stored in 1 dimensional, or
1D, tubes with the red triangles of the phosphates forming the walls and the blue octahedra of
the iron forming the floors and ceilings. These tubes restrict the movement of lithium
ions because they can only enter and exit the tubes one at a time, which slows down
the rate that the tubes can be emptied and filled. The process of lithium entering and exiting
the tubes is called diffusion. That is, LFP has a slow diffusion rate. With that said, the walls, ceilings, and floors
of the crystal structure also have a benefit. They keep the crystal from collapsing when
the lithium ions leave and result in a crystal structure that’s more chemically stable. One thing that’s not obvious from the image
of the crystal structure is that LFP is a poor electrical conductor. Why is this? In the centre of each blue octahedron is an
iron atom. There are oxygen atoms at each corner of the
octahedron that put extra distance between the iron atoms. In order for iron to conduct electricity,
each iron atom has to be within 3 angstroms of the next iron atom. The oxygen atoms at the corners of the blue
octahedra force the iron atoms to 4 angstroms apart. An angstrom is just a measure of length at
the atomic scale. The point is that the iron atoms can’t conduct
electricity with each other because they’re spaced too far apart. And, in order for a lithium ion battery to
work, the cathode has to conduct electricity to and from the grey lithium ions using the
cathode crystal as an electrical network. As a quick summary of LFP, it has a strong
crystal structure, but that crystal structure is poor at conducting electricity to and from
the lithium ions. Additionally, the lithium ions are contained
in 1D tubes which slow the diffusion rate of the ions. However, manufacturers of LFP batteries have
mostly solved the issues with electrical conductivity and ionic traffic jams in three ways. First, LFP batteries often use LFP cathode
particles less than a tenth of Micron in diameter compared to the 10 micron particles often
used in NCA batteries. That is, LFP crystals are 100x smaller than
NCA crystals. Reducing the particle size of LFP increases
surface area, which helps solve the ionic traffic jam problem by creating more entry
and exit points for a given volume of LFP crystals. Second, carbon coatings have been developed
that increase the surface conductivity of the LFP particles, which drastically increases
the conductivity between LFP particles. As we can see here, carbon coatings increase
the initial battery capacity by about 50%, from 80 mAh/g to 120 mAh/g. Third, dopants such as Magnesium have been
used to increase the conductivity within the LFP crystal, not just the surface. This raises the capacity from about 120 mAh/g
to about 160 mAh/g. By comparison, NCA has around 200 mAh/g of
useable capacity. In other words, in terms of the amount of
lithium that LFP can store, it’s only about 20% less than an NCA chemistry. If that’s the case why does a typical NCA
battery cell achieve 250 Wh/kg and a typical LFP battery cell achieve 160 Wh/kg, which
is 36% less rather than 20% less? It’s due to voltage. Watts are calculated by multiplying volts
by amps. LFP has an average voltage of 3.2 volts whereas
NCA has an average voltage of 3.7 volts, or 14% less. That is, a 14% energy density difference due
to voltage and a 20% difference due to lithium capacity gets us close to the 36% gravimetric
energy density difference between LFP and NCA at the cell level. There are other factors at play here, but
this back of the napkin calculation explains the two largest factors at play for the gravimetric
energy density difference between the two chemistries. Gravimetric energy density means the amount
of energy storage for a given weight of material, or wh/kg. This is as opposed to volumetric energy density,
which is energy storage for a given volume of material, or wh/l. We’ll cover both gravimetric and volumetric
energy density at the cell and pack level later in the video. Before we wrap up LFP, there’s one more
note regarding voltage. LFP has an extraordinarily flat voltage profile. As the battery charges and discharges, the
voltage range is confined between 3.1 to 3.3 volts for the majority of the cycle. Why is this? The voltage in a battery cell is dictated
by the natural voltage potential between the cathode and anode. During charge and discharge, the chemical
composition of both the cathode and anode change as lithium shifts between the cathode
and anode. As the chemical composition changes, so does
the voltage potential. The changes in chemical composition are called
phase changes and they appear as physical changes in the crystal structure of the cathode
and anode. In NCA cathodes, the lithium ions are free
to shuffle around in their 2D planes. As they shuffle around, the entire crystal
structure changes continuously and in a unified way. That is, every part of the cathode structure
remains electrochemically active throughout the charge and discharge cycles. This results in the gradual slope we see in
the charging profile of high nickel and high cobalt batteries. The entire crystal structure of the NCA and
graphite are gradually changing which shows up as a moderately steep but smooth slope. Let’s contrast this with LFP. As lithium ions leave the 1D tubes in the
LFP crystal, those parts of the crystal structure become electrochemically inactive. That is, the voltage potential of the cathode
remains steady because the cathode continues to react from the active core, while the surface
shuts down and remains chemically and structurally separate. This trick of maintaining two different crystal
structures within the same crystal is called a two phase crystal structure. Let’s do a quick summary for LFP and then
move on to NCA. Out of the box, LFP has issues with conductivity
and moving ions in and out of the crystal structure. This was solved by making the LFP particles
smaller, adding a carbon coating, and doping it up with elements like magnesium. Without those innovations, LFP wouldn’t
have been commercially viable. Even with those innovations, LFP is outperformed
at the cell level by NCA. The gravimetric energy density of LFP is lower
than NCA by about 36% for cells like CATL is using. However, as we’ll see, the higher stability
of the LFP crystal structure results in a safer battery cell that requires less packaging. This means that at the pack level, LFP closes
some of the performance gap with NCA. The two-phase crystal structure of LFP generates
the flat voltage profile we see in LFP batteries. This flat voltage profile has some advantages
for hardware and software engineers because it provides voltage and current that are more
steady and less dynamic. However, it can also pose a challenge for
vehicle manufacturers that are used to NCA based battery cells. The state of charge of a battery is usually
measured through voltage, and with such a narrow voltage profile, you can get whacky
state of charge readings in cold weather. We’ll come back to cold weather performance,
but first we need to cover off NCA. In NCA, the lithium is the grey spheres again
and the NCA is orange. The lithium here is stored in 2 dimensions,
or planes, which we’ll call slabs. The ions can enter and exit the crystal structure
relatively freely because it doesn’t have walls like LFP. This means a high lithium diffusion rate. As for electrical conductivity, the nickel
atoms are tightly packed and the NCA cathode material conducts electricity freely to and
from the lithium ions. What’s not to like? Well, the crystal structure is weak. As lithium is removed from the lithium slab,
the crystal structure becomes weaker and more reactive. Even though the NCA crystal structure can
hold quite a bit of lithium at 274 mAh/g, the amount of lithium that can be safely removed
limits that capacity to around 200 mAh/g. Some of the lithium ions must remain in the
NCA crystal to serve as pillars to hold up the Nickel Oxide slabs, which would collapse
without the lithium. Furthermore, just like the blue iron octahedra
had oxygen at each corner, the orange nickel octahedra also have oxygen at each corner. However, whereas the oxygen bonds in the LFP
are strong, the oxygen bonds in the NCA are weak. This means NCA loses oxygen more easily, and
oxygen is fuel for fire. While we’re on the topic of safety, how
do LFP and NCA compare? First, a quick primer on battery fires and
thermal runaway. When a battery cell shorts out, all of the
energy in the cell is released in a matter of seconds, generating heat. The heat drives side reactions that release
oxygen, generating more heat which drives more side reactions. This loop is called thermal runaway. NCA starts decomposing and releasing oxygen
gas at around 150 Celsius. When it decomposes, it releases heat on the
order of 940 Joules per gram. That is, thermal runaway is triggered at lower
temperatures, the thermal runaway is more intense, and releases more oxygen. The end result is an explosive reaction the
culminates in a molten fireball. LFP on the other hand starts decomposing and
releasing oxygen gas at 270 Celsius. When it decomposes, it only releases 200 Joules
per gram. This
leads to a hot battery that bursts but doesn’t necessarily turn into a molten fireball. Let’s do a quick summary of NCA before moving
on to pack level performance. NCA is higher energy density than LFP because
it stores more lithium and has a higher voltage potential. The drawback of NCA is that it’s less stable
and results in battery cells that are susceptible to violent thermal runaway events. LFP cells on the other hand, tend to burst
and smoke. Still dangerous, but more benign. Now on to how the performance of LFP and NCA
at the cell level translates to the pack level. Bear in mind that the numbers I’m about
to provide here are estimates. Or, I’ve chosen a round number that’s
easy to work with and within a few percent of actual. Some of the numbers simply weren’t publicly
available and I had to triangulate numbers based on multiple sources. Currently, NCA battery cells like Tesla’s
are above 250 Wh/kg and LFP battery cells like CATL’s are above 160 Wh/kg, or 36%
less. As for volumetric energy density, NCA battery
cells like Tesla’s are around 720 Wh/l and LFP battery cells like CATL’s are around
390 Wh/l, or 45% less. At the pack level, NCA battery packs like
Tesla’s are around 163 Wh/kg and LFP battery packs like CATL’s are around 128 Wh/kg,
or 21% less. As for volumetric energy density, NCA battery
packs like Tesla’s are around 238 Wh/l and LFP battery packs like CATL’s are around
168 Wh/l, or 30% less. That is, LFP is able to make up about 15%
of its gravimetric and volumetric energy density shortcomings at the pack level. This is because it’s a more durable chemistry
and therefore requires less protection. Less protection means less additional weight
and volume. People often wonder why Chinese battery producers
almost always opt for a prismatic cell for their LFP battery chemistries. It’s because large prismatic battery cells
are rectangular and fill a rectangular pack better than cylindrical cells. This helps make up for the poor volumetric
energy density of LFP. The volumetric energy density limitations
are also why the LFP standard range plus model 3 is limited to 253 miles of range vs 262
for the NCA version. Furthermore, it’s also why you can get an
even larger NCA pack for the Model 3 long range that provides 353 miles of range, or
40% more range, in the same space as the 253 mile range LFP battery pack. Again, these are rough figures. Tesla might be able to pack more LFP cells
into Standard Range Model 3s or more Nickel cells into the Long Range. But, the vast gap between LFP and NCA volumetric
energy density would remain, and it would still limit how much energy you can pack under
a Model 3 with LFP, and therefore limit its range. That is, Wh/kg is often used as the key metric
for lithium ion batteries, but with LFP the most important figure Wh/l, followed closely
by Wh/kg. Given that LFP battery packs have a lower
gravimetric energy density than NCA, they’ll be heavier. What does this mean for performance and handling? Let’s use the Standard Range Plus LFP vs
the NCA version as an example. The LFP battery pack results in a vehicle
that’s 125 kilograms heavier, resulting in an efficiency number that’s about 5%
less. Note that the pack size is about 1 kWh larger
in the LFP battery pack to make up for this, but the range is still 9 miles shorter due
to the greater weight. The 0-60 times appear to be unaffected, but
overall, the handling in the LFP Model 3 might feel slightly less agile, but not significantly
less agile. The impact would be less than having 1 large
person or two smaller people in the vehicle because the weight would be low slung in the
battery pack, as well as evenly distributed. Furthermore, the Model 3 is designed to carry
the long range pack and with dual motors, which are heavier than the LFP battery pack,
so the Model 3 has the powertrain, suspension, and crash protection in place to deal with
the extra weight. I have yet to see a track performance comparison
of LFP vs NCA Model 3s to see how this plays out, but LFP will probably perform slightly
worse due to the extra weight in comparison to an NCA pack. On that note, I’m not sure how the LFP battery
will perform at the track after multiple laps. This will come down to factors such as the
cooling system, which I’ve heard nothing about so far. But, if you’re buying a Model 3 for track
runs, you’d probably get the performance Model 3 instead. Consumers might see additional wear on things
like tires and brakes, but, this wouldn’t have a drastic impact on total cost of ownership. Furthermore, as we’ll see in a moment, the
extra battery life of an LFP battery pack will more than make up for any additional
brake and tire costs. What about fears of cold weather performance? The grey bars in this image show the performance
of a high nickel chemistry similar to NCA from -20 Celsius to 60 Celsius. The blue bars show an LFP chemistry in a similar
temperature range. As you can see, below 0 degrees the nickel
chemistry drastically outperforms LFP. The reason for this goes back the 1D crystal
structure of LFP we discussed earlier. The slow lithium diffusion between the electrolyte
solution and the LFP crystal structure was solved at warmer temperatures by using nanoscale
LFP particles. However, as the electrolyte solution gets
colder the lithium diffusion slows down and the 1D crystal structure again becomes a bottleneck. But, there’s an easy way around this – warm
up the pack. The red bars in this image show an LFP chemistry
that’s heated with an element to keep the pack warm in colder temperatures. The energy used by the heating element more
than makes up for the energy used during the heating process and results in cold weather
range that’s similar to what would be expected in warmer temperatures. Tesla’s have a similar function called pre-conditioning. The catch is that pre-conditioning takes up
to 45 minutes. But, for most people this isn’t an issue
because the pre-conditioning can be scheduled through the Tesla app. It can also be done while the vehicle is plugged
in to minimise any range loss. Last year and earlier this year, China made
Model 3’s with LFP battery packs were showing strange readings and were having cold weather
range issues. My guess is that this is due to a combination
of LFPs poor cold weather performance and the flat voltage profile. Regardless, Tesla pushed updates throughout
the winter which appear to have resolved those issues. It’s worth noting that all vehicles experience
range loss in cold weather, and electric vehicles are no exception. This is due mostly to the extra energy used
to heat the cabin, but also due to a number of minor factors like tire pressure, air density,
and road grip. The takeaway here is that down to about 0-10
Celsius, LFP performs similar to an NCA battery. At zero Celsius and below, LFP performance
degrades rapidly but can it be addressed with pack heating. However, at those temperatures, you’d probably
pre-heat the cabin and the battery anyways. Lastly, the cold weather issues that the LFP
packs in Model 3s were having appear to have been solved by software updates. The next point to cover about LFP vs NCA is
cycle life. On average, LFP has a cycle life 3-4 times
longer than NCA. This is for two reasons:
First, as we discussed earlier, the crystal structure of LFP is physically and chemically
more robust than NCA. Second, the voltage window of LFP is on average
about .5 volts less than NCA. That doesn’t sound like much, but it’s
enough to create a harsher chemical environment that degrades the battery cell. The benefit of long cycle life is obvious. An LFP battery pack with 253 miles of range
should last up to a million miles, possibly more. A not so obvious benefit of the long life
is that range will degrade less quickly. By the time an NCA battery with a range of
262 miles hits end of life, which is 80% capacity, the range will be 210 miles. An LFP battery with 253 miles of range will
only be half to a quarter of the way through its life at the same point that the NCA is
end of life. This means that when the NCA battery hits
80% of range remaining and 210 miles of range, the LFP battery will have 90-95% of its range
remaining with 230-240 miles of range. So, the LFP battery cell will actually have
longer range than NCA for the majority of its useful life. The reason why LFP can be charged to 100%
comfortably is for a slightly different reason than the long cycle life but contributes to
long cycle life. As we covered earlier, LFP is a two phase
structure where parts of the crystal, for lack of a better term, deactivate as the battery
charges. This has a protective effect at a 100% charge
state when the crystal structure is empty. It’s not invincible at 100% charge state,
but LFP can certainly be charged to or kept at a 100% charge state more frequently and
with much less degradation than NCA. The 2D, single phase structure of NCA isn’t
as robust as the 1D two phase crystal structure of LFP. As an NCA cell is charged and lithium is removed
from the crystal structure, it becomes more unstable and reactive. Above about a 90-95% charge state NCA becomes
unstable enough that it begins releasing oxygen that degrades the battery, and at a 100% charge
the electrolyte begins to oxidise. You can charge an NCA battery above 100% charge,
but power electronics usually prevent this because it shortens the battery life, and
the chemistry becomes highly reactive and dangerous. Next, charge rate. The charge rate of the made in China Model
3 Standard range plus with LFP is pretty much in line with the Standard Range Plus produced
in Fremont with NCA. In the image on screen, LFP is in red and
NCA is in green. We’ll ignore the Model 3 in black because
it’s a newer vehicle with a newer cell chemistry and Tesla might still be dialling in the charge
rate. Right outta the gates the Fremont Model 3
accepts a higher charge rate. This is likely due to the Silicon in the NCA
battery cell. If you’d like to know more about why Silicon
can accept a higher charge rate, check out my Silicon fast charge video. By 40% state of charge, LFP catches up to
NCA, and above 75% state of charge LFP accepts a higher charge rate. I’m not sure why the LFP performs so well
above 75%, but I’m guessing that it’s because the LFP cell contains more synthetic
graphite. If you’d like to know more about synthetic
vs natural graphite, check out my video by that name. Overall, below 40% state of charge, NCA is
faster than LFP. Between 40-70% state of charge, LFP and NCA
are neck and neck, and above 70% state of charge LFP is faster. Bjorn Nyland’s YouTube channel shows the
real time video results, and on screen is a snapshot of LFP vs NCA at the point that
LFP hits a 90% charge state. As you can see, the NCA lags slightly behind,
but they’re comparable. So, regardless of which chemistry a customer
chooses, charge rate probably won’t be a big consideration. With regards to cost, that was covered in
the last LFP video on LFP licensing. In short, LFP packs are about 20% cheaper
if they’re manufactured in the same country as the vehicle that they’re installed in. If they’re shipped from China to the US
for example, the cost savings would be minimal and might be break even. That is, don’t expect price cuts with LFP,
especially when Tesla has a 4-6 month order backlog. Closely related to cost is raw materials availability
and scaling. Iron is about 100x more abundant than Nickel. This means that no matter how large the LFP
battery industry scales or how quickly, iron will not become a bottleneck. Lithium may become a bottleneck at some point,
but according to benchmark minerals things are looking pretty good until the mid-2020s. But, that might change given how quickly battery
cell production plans are accelerating. Overall, there could be a number of raw materials
that intermittently become the bottleneck for battery production like copper, rare earths,
and graphite. As always, this doesn’t mean growth stops,
but that growth either slows or the most efficient producers like Tesla and Chinese companies
devour the supply chains of their competitors and sweep the table. In summary, for most people, based on the
research I’ve done and the reports coming out so far, LFP batteries may be a better
choice for most people. However, ultimately, it comes down to the
needs of the specific buyer, availability of cells, and vehicle price. Personally, if I can, I’m gonna get a Model
3 with LFP battery cells. This’ll come in especially handy if the
Tesla robotaxi network comes online. That use case will put miles on the vehicle
quickly and I expect the LFP chemistry could at least triple service life at no additional
cost. Rather than rehash all the key points in the
video for this summary, I’ve made this image so you can compare and contrast LFP and NCA. Overall, NCA is more energy dense, but LFP
has greater safety, longer cycle life, and greater raw materials availability. LFP does have some cold weather issues due
to the slow lithium diffusion and flat voltage profile, but with battery pre-conditioning
and software updates these appear to be problems Tesla can work around. As Elon Musk has said, Tesla will switch all
their standard range vehicles to LFP batteries. As an investor, I couldn’t be happier about
this. LFP will increase safety and reduce the risk
of costly recalls. Furthermore, LFP is more scalable than Nickel
based chemistries and it’s ideal for a subcompact Tesla Model Q, or whatever they end up calling
it. With LFP battery packs, they should be able
to pump out several million of these subcompact vehicles each year with a lot less stress
than they would have with a Nickel supply chain. I would be surprised if a subcompact Tesla
ends up being the Toyota Corolla of the 21st century, which’s sold 43 million vehicles
since it started production in 1966. In the next video of the LFP series, we’ll
cover the BYD blade battery. If you enjoyed this video, please consider
supporting me on Patreon with the link at the end of the video. I am also active on Twitter. You can find the details in the description,
and I look forward to hearing from you. A special thanks to NorseWorks, Mark Jay McCain,
@EugeneGTI for your generous support of the channel, my YouTube members, and all the other
patrons listed in the credits. I appreciate all your support, and thanks
for tuning in.
As always The Limiting Factor is the GOAT. This one might be one of his best video, exceptionally clear and the animation, that he does in-house are top notch and very readable.
Insane that this high quality info is available to anyone, for free. I know that you'll read this Jordan, thank you.
Calling it, recycled batteries will be cycled back into megapacks and robotaxis.