<h4 style="display:none;" Science —

What to worry about when you’re worrying about lithium-ion batteries

We’re living in a time when new technology is extremely material-dependent.

In late September, Volkswagen Group issued a call for long-term contracts with cobalt producers. Cobalt is an important component of lithium-ion batteries built for electric vehicles (EVs), and VW Group’s call signaled that the company was ramping up its promise to focus on EVs in the aftermath of the company’s diesel emissions scandal.

But by mid-October, the 金融时报 报道 that VW Group’s overtures had failed, and the company could not find a company to contract with. Reportedly, the prices VW Group offered for cobalt were too low, and the German automaker wanted to agree on a fixed price for the duration of the contract—at a time when cobalt prices were going up.

VW Group’s failure to secure a contract exposed a lurking problem with lithium-ion batteries—that is, development and mass production of them can be held up and complicated by materials other than lithium. And because there aren’t always great alternatives for the lightweight, energy-dense materials that make up these batteries, researchers are concerned about supply chains for the materials that drive innovation. Do we have enough lithium? And do we have enough of the secondary materials that make lithium-ion batteries work, like cobalt, nickel, manganese, and natural graphite?

Researchers from MIT, Berkeley, and Rochester Institute of Technology tried to answer these questions in a recent paper by looking at potential threats to the supply chains of components in lithium-ion batteries. Although most of the materials used in these modern batteries aren’t in any danger of suffering significant shocks to supply and likely won’t have trouble meeting future demand, the exceptions are cobalt, a cathode material that helps extend the lifetime and cycling ability of lithium-ion batteries and, to a lesser extent, lithium itself.

Cobalt, the researchers say, is a real issue. The mineral is primarily a byproduct of nickel and copper mining, but 50 to 60 percent of the global cobalt supply currently comes from the Democratic Republic of Congo (DRC) due to the high-grade ore that’s found in that country. But in the DRC, political strife can easily disrupt the cobalt market. (There are ethical issues with the DRC’s mining operations, too: UNICEF and Amnesty International estimate that 40,000 children are involved in cobalt mining in that country.) If the DRC isn’t able to adequately meet demand, that could “create significant price volatility and commodity price uncertainty,” the researchers write.

And any disruptions in cobalt price could have a significant effect on battery-dependent technology, especially electric vehicles. Electric vehicle makers favor lithium-ion batteries with cobalt for their high-energy density, and about 50 percent of all cobalt produced ends up in rechargeable batteries, according to the Cobalt Institute

But what about lithium?

For lithium, the issue is not that the material is hard to come by but that near-term supply may not be able to meet explosive demand out to 2025. Ultimately, though, lithium’s relative abundance around the world suggests that medium- and long-term, lithium demand will be met. The researchers write that “the challenges of Li [lithium] production are not whether there is enough material, but rather whether production can ramp up quickly enough. Just examining whether supply meets demand does not provide insight into this rate problem.” Demand for lithium-ion batteries increased 73 percent between 2010 and 2014, the researchers write, but production only grew by 28 percent.

Still, researchers aren’t terribly worried about lithium supply because there’s evidence that suppliers are gearing up to get into the market and meet that demand. “[B]ased on the supply diversity and the significant attention this topic has received, many firms are positioned to respond relatively rapidly to disruptions,” the paper notes. If there’s going to be a supply shock, it won’t last too long. That’s good because the researchers also noted that in the event of a supply shock, lithium demand is not likely to be met by recycling. Batteries have long lives before their components can be reused, and there’s currently not a big enough stock of scrap batteries that a supplier could recycle them economically. (Recycling lithium is also still pretty expensive compared to extracting new lithium.)

A word about natural graphite

The researchers also note that natural graphite, a component used in the anodes of lithium-ion batteries, has a high concentration of supply coming from one country (China), just like cobalt. But they shrug off the immediacy of supply disruptions. For one, China’s government is more stable than that of the DRC. But natural graphite is also relatively abundant throughout the Earth’s crust. We’re also able to produce synthetic graphite if necessary, although it’s more expensive.

Simply knowing which raw materials could threaten the explosion of electric vehicles and other battery-dependent technology is a first step to preventing that threat. Cobalt supply is a concern, but the silver lining is that cobalt can be substituted out from lithium-ion batteries, usually with some combination of nickel, aluminum, or manganese. Although cobalt is the favored secondary material in lithium-ion batteries today, the authors of the Joule paper recommend continued research into cobalt-free cathode materials.

Joule,2017 DOI: https://doi.org/10.1016/j.joule.2017.08.019关于的DOI)。

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