in Electric vehicles

About NCMA, the Battery Chemistry Used in the Hummer EV

The electric monstrosity from GM takes advantage of years of gradual improvements to Li-ion technology.

Photo: on Youtube

Even those who are not really into EV battery chemistry might have heard that Tesla started using LFP batteries, instead of “normal” Li-ion batteries, in some of its products. LFP batteries are nickel-free.

It started in 2020 with the made-in-China shorter-range variant of the Model 3, but then expanded to other variants, including those shorter-range Model 3s that are made in Fremont. Additionally, Tesla switched to using LFP for its Megapacks.

So, there are “normal” Li-ion batteries, and then there are LFP batteries: cheaper, nickel-free, with longer cycle life, but lower energy density… right?

Well, yes, but an often overlooked fact is that these “normal”, nickel-containing Li-ion batteries also come in different variants. And Tesla has long used a different variant than the rest of major EV manufacturers.

NCA, Tesla, and the birth of long-range electric cars

With the Model S, Tesla tied its future to NCA batteries.

NCA stands for nickel-cobalt-aluminum. Most Western automakers today use NMC, nickel-manganese-cobalt.

The earliest Tesla Roadsters used LCO (lithium cobalt oxide) chemistry. Batteries of that kind, known for their high energy density, have been used at least since the 1990s in cell phones, laptops, cameras.

Later, for the Model S, Tesla chose NCA batteries, supplied by Panasonic. The deciding factor seems to have been – again – the energy density. The data I found at one website suggest that, at the time, NCA had an advantage over NMC in this respect.

So, for the Model S, Tesla used batteries that – at the time and among those available commercially in larger quantities – had their energy density pushed to the maximum; and packed them into a vehicle designed to have very low aerodynamic drag. Same recipe as in the 1999 (second-gen) GM EV1.

The Tesla Model 3 and the Model Y also started as vehicles using NCA cells.

Established automakers (“legacy” automakers), if they decided to make an all-electric vehicle at all, would often use NMC cells. And these cells would often come from LG Chem or SK Innovation.

(This does not apply to pioneers like Nissan with its first-gen Leaf and Mitsubishi with the i-MiEV – they both used different chemistries.)

NMC batteries kept evolving, and in the second half of 2019 none other than Tesla started using them in the made-in-China long-range variant of the Model 3 (and then also the Model Y).

The shift to high- and very-high-nickel batteries

Generally speaking, increasing nickel content in NMC batteries results in higher energy density. Another reason to increase nickel content is to reduce cobalt content.

Designations of various kinds of NMC batteries indicate the proportions of nickel (N), manganese (M) and cobalt (C) atoms in them. For example, NMC622 means that these proportions are 6:2:2.
There was a shift, in recent years, from variants containing quite a lot of nickel toward variants containing even more nickel, like NMC811 (proportions 8:1:1).

NCA batteries, on the other hand, already had a high proportion of nickel back in the year 2012. In those used by Tesla, the proportions of nickel:cobalt:aluminum were 8 : 1.5 : 0.5.

In these two last examples (NMC811 and old NCA), the nickel content was 80%. That doesn’t mean that 80% of the battery is nickel; nickel is 80% of what you get if you take the so-called active material of the cathode – a powdery substance that is just one of multiple things that come together to form a battery cell – and then consider only the part of it that isn’t lithium or oxygen. (And another thing, although it does not change much in this case: these are not proportions of weight but proportions of atoms. So 80% nickel and 10% manganese means there is not eight times more, but actually *over* eight times more kilograms/pounds of nickel than manganese. Because one atom of nickel is slightly heavier than one atom of manganese.)

According to an article published in 2019, when you try to increase the proportion of nickel even further, to 90%, the result is a battery with low cycle life (it will need to be replaced after too few cycles of charging/discharging), at least in NMC or NCA batteries. And here is where the new NCMA (nickel-cobalt-manganese-aluminum) battery chemistry, described in the same 2019 article, offers an advantage: it allows for raising the nickel content to about 90%, but without sacrificing battery longevity that much.

NCMA technology is championed by LG Energy Solution, formerly part of LG Chem.

SK Innovation, their competitor, seems to disagree that this new chemistry is required. They developed a 90% nickel battery which is still an NMC battery (proportions 9 : 0.5 : 0.5). And Samsung’s “Gen 5” battery is NCA (yes, NCA) but also close to 90% nickel content.

Meanwhile, in some (if not all) applications, LG reduced the nickel content in their NCMA cells to 85% instead of 90%.

Tesla announced in 2021 their imminent switch to LG-supplied NCMA cells for longer-range variants of their made-in-China vehicles; and I assume they went ahead with it.

General Motors, in partnership with LG, is also using NCMA for their Ultium batteries. According to GM, Ultium is a whole architecture (batteries, motors, control software) that can be adapted to different vehicles. Just a thought: it might be beneficial to keep a well-publicized name even if the underlying technology changes; so, Ultium might not necessarily be associated with NCMA in the future.

But for now, in the Hummer EV, an Ultium battery is an NCMA battery. With 212.7 kWh of capacity.

One could argue that the designers of the Hummer EV were not that concerned with vehicle weight – the curb weight of the pickup truck is 4111 kg (9063 lb). But still, that battery capacity is impressive, by current standards.

The Hummer EV seems like a good truck for towing: with its huge frontal area, it deals with so much air resistance when driving without a trailer that adding one couldn’t reduce the MPGe very much. Seriously though, that large battery capacity should make it possible to plan long trips with a travel trailer in a (relatively) painless way, with longer distances between charging stops.

American pickups, Korean rivalry

While General Motors went with LG Energy Solution’s NCMA battery chemistry, Ford is using batteries from SK Innovation for the F-150 Lightning.

A 2021 press release by Ford mentioned that 90% nickel, or “Nickel 9” batteries from SK Innovation were going to be used in the F-150 Lightning. As mentioned before, SK Innovation increased nickel content to 90%, but did that without switching to NCMA.

The rivalry between LG and SK seemed quite bitter, with SK being, quite recently (early 2021), banned by the U.S. International Trade Commission from importing both complete products and components into in the U.S. because of using what LG said was LG’s technology. An exception was made for the F-150 Lightning program, allowing for domestic production of batteries from imported components, but that exception would expire after four years (a less generous two-year exception was made for Volkswagen).

In the end, the ban was lifted, as an agreement was reached between LG and SK. SK agreed to pay LG $1.8 billion. Interestingly, that sum would nicely cover LG’s expenses caused by having to compensate another party – General Motors – for Bolt fires.

Sources: [1],[2]