Hello! Welcome back to Battery Week — where we use the term ​“week” somewhat loosely.

Up until now, we’ve been focusing on lithium-on batteries (LIBs) — why they are so important, how they work, and the varieties of LIBs that are battling it out for the biggest battery market, electric vehicles (EVs).

It’s fairly clear from that discussion that LIBs, in some incarnation, are going to dominate EVs for a long while to come. There is no other commercial battery that can pack as much power into as small a space and lightweight a package. Plus, LIBs have built up a large manufacturing base, driving down prices with scale and industry experience. Their lock on the EV market is likely unbreakable, at least for the foreseeable future.

But there’s another battery market where some competitors hope to get a foothold: grid storage. They think there’s space in that market waiting to be claimed.

Currently, there’s a robust and growing short-duration grid storage market, offering storage of anywhere from seconds (to provide grid services like voltage and frequency regulation) to four hours. LIBs have about 99 percent of that market locked up; in some areas, projects with solar power coupled with four hours of storage are bidding in competitively with natural gas.

Most energy wonks believe that in order to fully shift the grid to zero-carbon energy, we will eventually need long-duration storage as well, to the tune of weeks, months or even seasons. LIBs are almost certainly not going to cut it for that purpose, so it will be some combination of other technologies. (I’ll write about long-duration storage some other time.)

In between short and long, there’s something that might be called mid-duration storage, covering the range between four and 24 hours. What technologies will cover that range? LIBs can do it, of course — theoretically they can cover any duration; you just stack more and more batteries — but the economics get extremely difficult. Mid-duration projects will require lots of capacity but might run comparatively rarely. As duration gets to four hours and above, the cost of LIBs, at least today’s LIBs, starts to get prohibitive.

This is where other batteries come in, challengers to LIBs that hope to beat them at longer durations — though they aren’t quite there yet. ​“There really aren’t competitive technologies in the battery electric vehicle space aside from all these different lithium-ion batteries,” says Chloe Holzinger, an energy storage analyst at IHS Markit. But, she added, ​“there’s a ton of different battery technologies for grid storage. They just tend to be significantly more expensive than lithium-ion batteries.”

Companies offering these challengers believe they are better suited to the needs of the mid-duration grid storage market, where energy density matters less than capacity, calendar and cycle life, and safety. They think they can bring costs down to competitive levels at those durations. (Some of them think they can find other niches as well, but it’s grid storage that offers the most realistic shot.)

Flow batteries

Flow batteries operate on a fundamentally different principle than the batteries we’ve looked at so far. Rather than storing energy in metals on the electrodes, they store energy as a dissolved metal in an aqueous electrolyte.

The anolyte is stored in one tank; the catholyte is stored in another. Pumps circulate the fluids past electrodes (sometimes in a fuel cell) where they don’t quite mix, thanks to a thin separator, but they exchange ions and electrons, generating electricity.

The key conceptual difference is that flow batteries separate energy (the amount stored) from power (the rate at which it can be released). If you want more power, you make the electrodes bigger. If you want to store more energy, you make the tanks of electrolytes bigger. And electrolytes are fairly cheap, so it’s cheap to increase capacity.

This is in contrast to LIBs, which double in cost with each doubling of energy capacity.

Welcome back to Battery Week! So far, we’ve talked about why lithium-ion batteries 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. Several others are 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 lithium-ion battery research these days is aimed at improving the dominant batteries on the market, mainly by reducing the amount of cobalt (the most toxic and expensive ingredient) required for manufacturing.

Most EV makers use NMC batteries; Tesla uses NCA. In the past, it has 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 unique 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 the use of manganese — a much more stable, abundant material — and reduce cobalt.

We’ve discussed why lithium-ion batteries (LIBs) are so important to decarbonizing both transportation and the electricity sector.

Next week, we’re going to get into the nuts and bolts of different kinds of LIBs to see how different chemistries offer different kinds of performance benefits and are competing for different market niches.

Before that, though, it’s worth the time to do a little review of batteries and how they work. If you’re like me-a-month-ago, you probably have a hazy understanding at best of the structure of batteries and the processes involved in running them.

I’m not going to get into any deep chemistry — believe me, no one wants that — but I thought it would help to run through some basics and some terms. It will come in handy later when we get into the competition within battery markets.

Batteries 101

F---ing batteries, how do they work?

It is time to get into batteries. Waaay into batteries.

Over the next few posts, I’m going to cover how lithium-ion batteries (LIBs) work and the different chemistries that are competing for market share, but I thought I would start off with a post about why I’m doing this — why batteries are important and why it’s worth understanding the variety and competition within the space.

Lithium-ion batteries are crucial to decarbonization in two important sectors

We know that the fastest, cheapest way to decarbonize, especially over the next 10 years, is clean electrification: shifting the grid to carbon-free sources and shifting other sectors and energy services onto the grid.