The many varieties of lithium-ion batteries battling for market share

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Hello, everyone, and welcome back to Battery Week!

We’ve talked about why lithium-ion batteries (LIBs) are so important and we went through a basic primer on how they work. Today, we’re going to get into the competition within the broad lithium battery family, among all the different kinds of batteries that use lithium and exchange charged lithium ions. (See the previous post for a full list.)

There are a few clear leaders — lithium nickel manganese cobalt oxide (NMC), lithium nickel cobalt aluminum (NCA), and lithium ferro phosphate (LFP) — that have achieved mass market scale and several others looking to get in on the action.

The market prize is likely to exceed a trillion dollars within the next decade, so if any of these competitors can even carve out a substantial niche, it could be worth billions. Let’s look at the players.

Better NMC and NCA

The bulk of LIB research these days is going to improve the dominant batteries on the market, mainly by reducing the amount of cobalt (the most toxic and expensive ingredient).

Most EV makers use NMC batteries; Tesla uses NCA. In the past, it’s been difficult to push down the amount of cobalt in these batteries (it plays an important balancing role), but manufacturer LG recently introduced an NMC 811 battery: 80 percent nickel, 10 percent manganese, 10 percent cobalt. GM will use them in its new line, including in the Hummer, and Tesla will put them in some of its Model 3s in China.

Most big battery manufacturers, including Panasonic (which supplies many of Tesla's batteries), have vowed to gradually reduce and eventually eliminate cobalt.

Nickel is the key to energy density. Tesla, VW, and others are working on special high-nickel battery varieties that will be used for specialty vehicles that require extra-high energy density, like larger SUVs and trucks.

But not every vehicle needs that, and nickel supply constraints are looming, so work is also being done to further boost manganese — a much more stable, abundant material — and reduce cobalt.

Silicon anodes

Many LIB developers are experimenting with silicon as an anode coating, partially or completely replacing graphite. Tesla has been working to increase the proportion of silicon in its anode since at least 2015.

Silicon holds on to nine times more lithium ions than graphite, so energy density improves (range expands by 20 percent), and a silicon battery can charge and discharge much more quickly than graphite batteries, so power density improves as well. But silicon expands when it absorbs ions, so it breaks down quickly; cycle life is still much lower than graphite. If engineers can overcome that problem (and Tesla has vowed it can), LIBs could take a leap forward soon.

SILA Nanotechnologies, in its brief on the future of LIBs, considers silicon anodes the biggest potential near-term market-shifting breakthrough in the space. It summarizes:

[T]here are no high-volume commercial Li-ion batteries (yet!) in which a silicon anode entirely replaces the graphite one. When it does arrive, the reward will have been worth the wait. We expect automotive cells with NCA or NCM cathodes paired with Si-dominant anodes will increase energy density by up to 50%, thereby dropping the $/kWh cost by 30-40% in less than a decade.

That is a mind-boggling prize, if any manufacturer can unlock it. (Read Canary’s Julian Spector on Sionic, a battery company that has recently debuted a silicon anode that it says can fit into existing LIB manufacturing.)

Silicon anodes are technically “cathode agnostic,” though most testing so far has used NMC cathodes. If engineers can crack the code and make silicon anodes with high cycle life, it could benefit any and all cathodes (e.g., see LFP below).

Fluorides as cathodes

One thing I didn’t mention about silicon-as-anode: it doesn’t operate via intercalation. Instead of nestling into the anode, ions react with the silicon and bond with it, a process called “conversion.” That makes it more difficult to peel the ions off without damage, but it can hold way more ions.

With anodes (which are the limiting factor on most batteries now) improving, there’s more room for cathode improvement. SILA is big on research into fluorides — it cites metal fluoride-based cathodes (like iron fluoride or copper fluoride) and sulfur-based cathodes — which also operate via conversion rather than intercalation and can also store more ions. It writes:

It’s plausible that with a conversion cathode and an engineered low-swell silicon anode, the cycle life of Li-ion can be extended all the way to 10,000 full cycles while also having the highest energy density in the market — thus breaking the [power vs. energy] compromise.

SILA believes it’s only that combination — a conversion-based anode and a conversion-based cathode — that can bring LIB prices down to “~$50/kWh by 2030 and ~$30/kWh by 2040.” If it happened, that would be absolutely wild and almost certainly crush all competitors.

Lithium ferro phosphate (LFP)

LFPs, which use a lithium-iron compound as cathode, were among the first LIBs to commercialize. They are already standard in China, used in its ubiquitous scooters and small EVs. “The big Chinese battery makers — BYD and CATL and Lishen — each one of those is larger by itself than any other battery company that's not in China,” says Lou Schick, director of investments at Clean Energy Ventures, “and they have been making lithium iron phosphate cells for 10 years.”

A few years ago, it looked like LFPs were going to be displaced by NMCs and NCAs, but lately they’ve made a comeback and now have a decent case that they could take the lead in the EV and stationary storage markets. They have already captured almost half of the Chinese EV market.

LFPs use lithium ferrophosphate (LiFePO4) as the cathode, replacing nickel, manganese, and/or aluminum. The advantages relative to nickel-based competitors:

* cheaper on a materials basis (though not yet on $/kWh);

* higher cycle life (Matt Roberts, previously executive director of the Energy Storage Association, now working at battery company Simpliphi, says his company’s LFP batteries are warrantied for 10,000 cycles, compared to 2,500 to 5,000 for cobalt batteries.);

* higher power density;

* high safety and low toxicity (“They're almost literally bulletproof, in that they can't catch fire,” says Schick.);

* replaces problematic and/or rare metals with iron, which is safe and abundant.

In exchange for these advantages, LFPs offer lower energy density (there are fewer spaces for ions to intercalate). However, because they are so safe, L