Wanted: Abundant transition metal to electrify the automobile for the global mainstream
Most automakers are dying to sell you—and the world—an electric car. But they’re up against the challenge of our global-warming time: dauntingly tight supplies of both batteries and the ethically sourced raw materials required to make them.
Tesla and Volkswagen are among the automakers who see manganese—element No. 25 on the periodic table, situated between chromium and iron—as the latest, alluringly plentiful metal that may make both batteries and EVs affordable enough for mainstream buyers.
That’s despite the dispiriting history of the first (and only) EV to use a high-manganese battery, the original Nissan Leaf, beginning in 2011. But with the industry needing all the batteries it can get, improved high-manganese batteries could carve out a niche, perhaps as a mid-priced option between lithium-iron phosphate chemistry, and primo nickel-rich batteries in top luxury and performance models.
“We need tens, maybe hundreds of millions of tons, ultimately. So the materials used to produce these batteries need to be common materials, or you can’t scale.”
Elon Musk made waves at the opening ceremony of Tesla Gigafactory Berlin, when asked his opinion on graphene in cells: “I think there’s an interesting potential for manganese,” Musk countered.
Regarding raw minerals, he underlined the ongoing industry flight from cobalt and now nickel: “We need tens, maybe hundreds of millions of tons, ultimately. So the materials used to produce these batteries need to be common materials, or you can’t scale,” Musk said.
At Volkswagen’s live-streamed “Power Day” in March—a seeming hat-tip to Tesla’s “Battery Day” spectacle—CEO Herbert Diess set off his own Muskian frenzy by announcing VW would build a half-dozen gigafactories in Europe by 2030, with a total of 240 gigawatt-hours of capacity. VW is already building EV factories in Tennessee and China. VW, despite its EVs outselling Tesla in Europe, is under intense competitive pressure from Tesla, and in the Chinese market where VW underperforms. The global giant is determined to cut its battery costs by half in entry-level models, and by 30 percent in mid-priced cars.
To get there, VW unveiled a versatile “unified cell” that can use multiple chemistries in a standardized prismatic design. Diess said about 80 percent of VW’s new prismatic batteries would spurn pricey nickel and cobalt in favor of cheaper, more-plentiful cathode materials—including potentially manganese.
VW’s aggressive strategy to move production of prismatic batteries in-house—the same format built by China’s Contemporary Amperex Technology Co., Limited (CATL), which supplies both VW and Tesla—blindsided its current suppliers of pouch-style batteries, South Korea’s LG Energy Solutions and SK Innovation. (VW tried to smooth the waters by saying it would honor existing battery contracts.)
So why this endless mixing-and-matching of formats and cathodes? And why manganese? It all hinges on what Musk and other experts cite as the looming, limiting factor in accelerating the EV revolution: the lagging rate of both battery production and the mining and processing of their raw materials.
In Berlin, Musk suggested the world will need 300 terawatt-hours of annual battery production to realize a full transition from fossil-fueled cars. That’s 100 times what Tesla projects it can produce by 2030, even with its own massive expansion of capacity. Nickel-rich batteries alone won’t get us there, despite currently unmatched energy density and performance. Other materials are required, with an ethical, diverse, uninterrupted pipeline to boot, even if, like manganese or lithium-iron phosphate—the flavor of the moment for EVs—the resulting batteries demand some compromises.
“I can see the logic, where if you can get it to a reasonable energy density, manganese becomes this in-between thing.”
—Venkat Srinivisan, Argonne Laboratories
“The higher number of minerals that go into a battery is a good thing,” said Venkat Srinivisan, director of the Argonne Collaborative Center for Energy Storage Science (ACCESS).
As a cathode material, manganese is abundant, safe, and stable. But it has never approached the energy density or life cycle of nickel-rich batteries, Srinivisan cautions. Buyers of early Nissan Leafs might concur: Nissan, with no suppliers willing or able to deliver batteries at scale back in 2011, was forced to build its own lithium manganese oxide batteries with a molecular jungle-gym-like “spinel” design. Those energy-poor packs brought just 24 kilowatt-hours of storage and a 117-kilometer (73-mile) driving range. Even that piddling storage and range rapidly degraded, especially in the southwestern United States and other searing climates, leaving customers howling. (It didn’t help that Nissan eschewed a thermal-management system for the battery.) A “Lizard” battery in 2014 with a modified manganese chemistry boosted capacity to 40 kWh, but still suffered short life spans.
Srinivisan said the story of EVs in the United States has been one of insatiable demand for power and driving range, which demanded the highest-energy batteries. That meant cobalt, typically a by-product of nickel and copper mining, and among the priciest battery elements. Cobalt production is also dominated by the Democratic Republic of Congo, which is linked to child labor in mines and other human rights abuses. Low-cobalt batteries have been the response.
“Everyone is thinking about substitutions for nickel and cobalt and how to recycle these things,” Srinivisan says.
General Motors and LG Energy Solutions’ pouch-style Ultium cells—which I recently tested for the first time in the GMC Hummer EV—use a nickel cobalt manganese aluminum chemistry that reduces cobalt content by more than 70 percent. With 200 kWh in a double-stacked cell sandwich—twice the size of Tesla’s biggest battery—the reborn Hummer combines a 529-km (329-mile) range with tri-motor propulsion, 1,000 horsepower, and a 3.0-second explosion to 60 miles per hour in its WTF (“Watts to Freedom”) mode. That battery, by far the largest ever shoehorned into an EV, also contributes 1,315 kilograms to the Hummer’s gargantuan 4,082-kg curb weight. (With GM gearing up mass production in Detroit, the Hummer might cause a battery shortage all on its own.)
As with Tesla’s best cells, GM’s cells use only small amounts of manganese to stabilize structures, not as a main cathode material.
According to the global materials and recycling company Umicore, more than 90 percent of manganese is mined for iron and stainless-steel production, with less than 1 percent going into batteries.
The next popular cathode mineral has been nickel, with a more diverse supply than Congolese cobalt, but hardly immune from geopolitical concerns. Global nickel stockpiles were already dwindling before Russia’s invasion of Ukraine in February. Investors and traders got antsy over potential bans or interruptions of metals from Russia, which produces about 17 percent of the world’s high-purity nickel. In March, nickel prices doubled virtually overnight, briefly topping US $100,000 per tonne for the first time, spurring the London Metal Exchange to suspend trading during the wild run-up.
For all these reasons—commodity prices, politics, ethics, security, shortages, long-term strategy, and hedging of bets—the industry is embarking on a diversification strategy, a smorgasbord of solutions. Or at least until some future Nobel winner comes up with something to replace lithium-ion entirely.
For the fickle automaker, even nickel is on the outs—at least among those focused on China, or on modest-range, more-affordable EVs. Tesla, VW, Ford, Chinese companies, and others are rapidly switching to lithium-iron phosphate (LFP) chemistries—invented in the 1990s and until recently viewed as yesterday’s news—for mainstream or commercial models. These batteries require no nickel or cobalt, just abundant iron and phosphate. Musk has confirmed a “long-term switch” to LFP for entry-level cars (including the Model 3) or energy storage.
High-manganese batteries being eyeballed by Musk and VW would also use less nickel, and zero cobalt. They appear affordable: According to analysts at Roskill cited at Power Day, a lithium nickel manganese oxide chemistry could reduce cathode costs by 47 percent per kilowatt-hour relative to nickel-rich designs. That has VW mulling manganese as a potential fit for mainstream models, with LFP for bottom-rung vehicles or markets, and bespoke high-performance packs for the likes of Porsche, Audi, Bentley, or Lamborghini.
“I can see the logic, where if you can get it to a reasonable energy density, manganese becomes this in-between thing,” Srinivisan says. Automakers might offset manganese’s lower cathode costs with slightly enlarged batteries, to bring range closer to par with nickel-rich designs.
Back in 2020, at Tesla’s Battery Day, Musk expressed optimism about the mineral:
“It is relatively straightforward to do a cathode that’s two-thirds nickel and one-third manganese, which will allow us to make 50 percent more cell volume with the same amount of nickel,” Musk said.
With Musk still struggling to bring his large-format 4680 cylindrical cell to market—now well behind schedule—experts caution that the technical challenges aren’t so straightforward. High-manganese batteries have yet to demonstrate commercial viability.
But the epic scale of the challenge has automakers and battery makers working the labs and scouring the globe for materials as common as dirt, not precious as gold.
This article appears in the July 2022 print issue as “Manganese: The Secret Behind Truly Mass-Market EVs?.”
source : https://spectrum.ieee.org