Ask a Scientist: In Search of a ‘Green’ Electric Car Battery

July 13, 2022 | 4:35 pm
A view under the hood of a 2017 Chevrolet VoltGeneral Motors
Elliott Negin
Former Contributor

Lithium-ion batteries are the most popular battery in use today. First commercialized in 1991, their cost has declined by a remarkable 97 percent over the last three decades, enabling the rapid growth of mobile phones, laptops and more recently, electric cars. Global demand for the batteries is projected to increase dramatically by the end of this decade, largely due to the growing adoption of electric vehicles (EVs) around the world.

More EVs is good news for the climate. After all, as a 2020 Union of Concerned Scientists (UCS) analysis shows—and an updated, soon-to-be-released analysis will confirm—EVs’ lifecycle global warming emissions are dramatically lower than that of gas- and diesel-powered vehicles. But mining the materials used in EV batteries, including cobalt, lithium and nickel, comes with its own set of public-health, environmental and human-rights challenges. Despite EVs’ considerable environmental benefits, it will be imperative to “green” the material sourcing process to ensure a more sustainable and ethical supply chain as the world transitions to an electrified transportation system.

Fortunately, scientists are on the case. They are altering battery chemistries to reduce reliance on certain metals, such as cobalt, for example, and coming up with ways to recycle and repurpose batteries to minimize the need for new raw materials altogether.

The Biden administration, which wants half of all new vehicles sold in the United States to be electric by 2030, has taken notice. In June 2021, it published National Blueprint for Lithium Batteries, which calls for cobalt and nickel to be engineered out of batteries. In addition, the Bipartisan Infrastructure Law Congress passed last November recognized the need to recover key materials from EVs and dedicated funds to support battery recycling.

Automakers, too, are paying attention. Last fall, Nissan announced that it plans to introduce cobalt-free batteries by 2028, while Tesla said it will shift to lithium-iron-phosphate batteries, which do not contain cobalt or nickel, for its entry-level Model 3 and Model Y cars.

UCS also is playing a role. Our Clean Transportation program, which has been documenting the benefits of EVs for years, recently added battery expert Jessica Dunn to its team. Dunn is a doctoral candidate in energy systems at the University of California Davis, where she has been serving as a co-facilitator for the Lithium-Ion Battery Recycling Advisory Group, which is advising the California Legislature. She also was the lead author of “Circularity of Lithium-Ion Battery Materials in Electric Vehicles” published by Environmental Science & Technology, a peer-reviewed journal, in March 2021.

So, when we received a question about how to address the drawbacks of lithium batteries, I turned to Dunn for a response. Allison D., from Caro, Michigan, wrote: “I was wondering what might be on the horizon for alternatives to lithium batteries for EVs. I was curious if there is a more ‘green’ way to mine for lithium or if there might be a better option altogether.”

Below is an abridged version of our conversation.

EN: First, welcome to the UCS staff. Great to have you on board. Before we get to Allison’s question, I think it would be helpful if you could briefly explain the difference between a battery in a gasoline-powered vehicle and a battery in an electric car to clear up any confusion folks may have.

JD: Thanks for having me! That’s a good question, because a gas-powered car battery and an EV battery are two very different animals, dissimilar in function, materials and size. A gasoline-powered vehicle contains a lead-acid battery, which is typically 12-volt, whose main purpose is to provide power for starting the car. This battery is usually between 30 and 60 pounds and can be easily replaced if it wears out. An EV is powered by a lithium-ion battery. These batteries typically take up the whole base of the vehicle, weighing in at about 1,060 pounds for a Tesla Model 3.

Now let’s talk about materials. A lead-acid battery mostly contains lead sulfate and sulfuric acid. They are relatively inexpensive materials, but they don’t result in a very energy dense battery, meaning they cannot store much energy per unit of materials. The lithium-ion battery contains various critical materials, which are expensive, but also result in a battery with higher storage capacity, greater efficiency, as well as a longer lifespan. These factors are the main reason lithium-ion batteries are the most popular today. Interestingly enough, early electric vehicle prototypes were powered by lead-acid batteries, but they could only travel short distances and had long charge times.

EN: OK. Let’s address the second part of Allison’s question first. Is lithium brine extraction preferable to open pit mines? Can either method be cleaned up?

JD: Both of these techniques have their downsides. Pit mining involves excavating rocks containing lithium, typically pegmatite, and transporting them for crushing, heating and chemical processing to recover the lithium carbonate. This type of mining damages the land and emits toxic air and water pollution, posing a threat to nearby wildlife and communities.

Lithium recovery through brine extraction also emits toxins, but often the main problem is it uses up fresh water. The process requires developers to pump brine from underground pools, called salars, to shallow pools where natural evaporation occurs. When there is a high enough concentration of lithium, impurities are removed and the lithium materials go to final processing. Facilities are generally sited in very arid climates, such as Salar de Atacama in Chile, diverting water away from local communities’ already taxed water supplies.

EN: The United States, which has some of the world’s largest lithium reserves, is not a leading lithium producer, but we appear to be on the cusp of a “lithium rush.” Currently there is only one large-scale US producer, Silver Peak in Nevada. The brine extraction facility opened in the 1960s and is producing a mere 5,000 tons a year, less than 2 percent of the world’s annual supply. But Silver Peak’s owner, Albemarle, announced last year that it planned to double output by 2026.

Then there is a new major development in the works: a brine extraction facility at the Salton Sea in California, which investors are calling “one of the most promising and environmentally friendly lithium prospects” in the country. The California Energy Commission estimates that there’s enough lithium in the Salton Sea to meet all of the United States’ projected future needs and 40 percent of the world’s demand. What’s your take on this project?

JD: It’s critical that developers source battery materials in a sustainable, ethical manner, and the Salton Sea project may be a good option. Also called Lithium Valley, the project has the potential to supply 600,000 tons of lithium per year with a relatively low impact. The process would extract lithium as a biproduct of geothermal energy, something that hasn’t been done yet at industry scale. It would be a much preferable extraction method than pit mining or typical brine extraction because it would use less water and land, as well as emit less carbon pollution.

Despite these benefits, the project will still require some fresh water, as well as require drilling to build some new geothermal facilities, and we won’t know how much pollution it will emit until developers complete their pilot demonstrations. Salton Sea area residents, who are economically disadvantaged and are already dealing with pollution, have raised concerns. The community has low water supplies, and lake evaporation has resulted in a significant amount of wind-blown dust, which threatens public health. The Salton Sea community has to be an active partner in the decision-making process. If done right, the project has the potential to revive the local economy by providing sorely needed public resources and high-paying jobs.

Putting all of that aside, the best source of lithium—and of all battery materials generally—would be what could be recovered by recycling what is already in use.

EN: That brings me to my next question. The current generation of EV lithium-ion batteries have an estimated 10- to 15-year lifespan. Some predict they could last even longer. I know this is an issue you have looked at closely. Can they be recycled and reused?

JD: All batteries can be recycled, and if they aren’t damaged, they also can be reused and repurposed for stationary storage. When a battery reaches the end of its life, it is expected to be at about 80 percent capacity. At that point it still has a lot of energy storage potential, and it can be used in a less-demanding storage application.

One stationary use example is providing back-up for variable renewable energy, such as solar or wind, which is vital for transitioning from fossil fuels to renewable energy. That is what’s so great about repurposing. Not only will it extend a battery’s lifespan, but it also means manufacturers will not have to produce a brand-new battery for stationary storage. The company B2U, the largest “second-life” operation in the country, currently supports solar generation in California. It’s just one of a number of companies entering the second-life market.

After a battery has reached the end of its useful life, it can be recycled to recover critical materials, including—but not limited to—cobalt, lithium, manganese and nickel. “Material circularity” can significantly reduce the impacts of EVs. A recent study found that reusing materials recovered through hydrometallurgical processing can cut global warming emissions by 30 percent. Considering the impacts associated with mining, using recycled material is a much preferable option.

EN: Is lithium-ion battery recycling happening at industrial scale? Or is it still hypothetical?

JD: EV batteries are already being recycled in the United States. For example, Redwood Materials, a hydrometallurgical recycling plant in Nevada that accepts consumer electronic and EV batteries, reports a material recovery rate of 95 percent. Redwood is just one of many companies that are expanding their recycling operations to handle the upcoming wave of retiring EVs. And Redwood is not only recycling materials. It also has plans to close the material loop by using recovered materials to manufacture new batteries. Forecasts predict that, under optimal conditions, recovered materials could meet more than half of lithium-ion battery material demand by 2040. This material circularity is key to making EVs greener.

EN: Are there any federal or state policies that require battery recycling?

JD: There are currently no laws requiring lithium-ion battery recycling. In 2018, however, the California Legislature passed Assembly Bill 2832, which set up an advisory group to recommend policies that would enable as close to 100-percent EV battery recycling as possible. I had the honor of co-facilitating this group, and it recently recommended that the Legislature enact an extended producer responsibility policy requiring auto manufacturers take responsibility for ensuring batteries are recycled.

While there are companies that are now recycling EV batteries, state and federal standards would guarantee that there is an entity responsible for ensuring batteries are recycled. The California advisory group discussed several other policies that could increase material circularity, including recycling efficiency rates, recycled content standards, requiring manufacturers to design batteries that can be recycled and reused, and establishing a reporting system to track EV batteries that have been retired and recycled.

EN: Researchers are now working on alternatives to the lithium-ion battery. In January, for example, chemical engineers at the University of Michigan announced they designed a lithium-sulfur battery that could quintuple EV ranges on a single battery charge. The National Science Foundation recently awarded a grant to a Binghamton University chemist to research sodium-ion batteries, because sodium is considerably cheaper and more widely available than lithium. And Solid Power, a Colorado company that has partnered with BMW and Ford, has just started a pilot project to produce solid-state batteries, which significantly extend EV ranges. What do you see as the most promising alternatives?

Today’s lithium-ion batteries are already enabling us to drive vehicles without emitting any tailpipe pollution and helping wean the country off of oil. At the same time, some companies are moving away using cobalt and nickel in the lithium iron-phosphate battery, which they make with cheaper and more environmentally friendly materials. And there is research underway, but not yet on the market, that could deliver even bigger gains.

I’m most excited about solid-state batteries because of their energy density—their ability to store more energy while using less material than lithium-ion batteries. The word “solid” in solid-state refers to the use of a solid electrolyte instead of liquid one. Complications with this technology stem from the difficulty electrons have in passing through the solid electrolyte and fast degradation due to buildup of lithium—called lithium-dendrites—shortening a battery’s lifespan. QuantumScape, a solid-state, lithium-metal battery startup, claims it has solved this problem using a ceramic electrolyte material, and is set to start production within the next couple of years.

If solid-state batteries are commercialized, EVs would use fewer critical materials than they do with lithium-ion batteries. That would mean less critical material mining and a greater likelihood that battery manufacturers could use more recycled materials.

Material circularity is already happening to a certain extent. As I mentioned before, companies are developing lithium-ion cathode chemistries with lower cobalt content. The lithium-ion batteries with nickel-manganese-cobalt cathodes that were first used in EVs had equal amounts of the three metals. Now, manufacturers are producing these batteries with eight parts nickel, one part manganese, and one part cobalt. This new configuration allows battery makers to recycle cobalt from one older generation battery to produce several new batteries. Considering this circularity advancement mainly relies on substituting metals, the potential impact of high material reduction from a new technology like solid-state batteries would be even greater.