Batteries are the key to our clean energy future, but what about the materials necessary to make them? How “dirty” are batteries?

It’s worth digging into (sorry, pun intended) how people make batteries because batteries are the single most important technology for our clean energy transition. Don’t believe the “toxic batteries” hype: although nickel, cobalt, lead, and mercury were used in older batteries, those problematic ingredients are not in new kinds of batteries. Cobalt-free lithium-based batteries are becoming the new standard, with sodium and iron batteries nipping on their heels as more affordable options. In the future, thanks to recycling and better battery chemistries, we won’t have to mine nearly as much material, but for the next few decades, our world will mine and refine lithium and a few other building blocks for humanity’s next stage of civilization.

Why We Need Lots of Batteries

The two main reasons we need a lot more batteries are to store solar electricity and to make our gadgets go.

Storing Solar Electricity

Everyone used to think that nuclear power would be the best way to generate carbon-clean electricity, even though uranium mining has been an environmental justice horror show. (A quick aside about that: four million tons of uranium were taken from Navajo land between 1944 and 1986; contamination from that legacy likely explains why the Navajo Birth Cohort Study found that 27% of participants in 2015 had high levels of uranium in their urine, compared to 5% in the general population, and why Navajo cancer rates doubled between the 1970s and 1990s.)

Now we know that solar power is the best way to make carbon-clean electricity, and it’s becoming even better as solar cells become incredibly affordable. (One reason is that silica, one of the most common minerals on Earth and the primary material in solar cells, has been mined all over the world with less environmental and health consequences than uranium.) But as our world generates more electricity from sunlight, we get too much electricity when it’s really sunny and not enough when the sun goes away—hence the need for batteries.

Nuclear power plants and solar farms are both much more practical when paired with energy storage but for opposite reasons. Nuclear power plants heat up water to spin turbines. It works best to run these plants at full throttle all the time. Back in the 1970s and 1980s, when the world loved nuclear power, we didn’t have good battery technology, so we built pumped hydropower plants to store excess electricity at night when we don’t need it, then put it back on the grid during the day.

Solar photovoltaic cells generate lots of electricity on long summer days during clear weather, less when it’s cloudy, and none at night or when cells are covered in snow. So while nuclear is an “always on unless its broken” electricity source, sunlight is a “you never really know” intermittent electricity source. To “firm” solar electricity, i.e., make it a “you can count on me” electricity source, we need to store it. We can use pumped hydropower plants—they don’t really care if they are storing nuclear power or solar power; it’s all electrons to them—but now that we have invented better batteries, we have a better option.

The main reasons the world has fallen out of love with nuclear power and pumped hydropower storage and is falling in love with solar power and batteries are speed and convenience. The disparity between nuclear and solar is playing out most vividly in China, which failed to achieve its 2020 goal of 58 gigawatts (GW) of nuclear power but was able to add 216 GW of solar power in 2023 alone, being five years ahead of schedule toward its goal of 1,200 GW of renewable power by 2030. Here in the United States, since 1996, we’ve installed just three new nuclear power plants—a 1.165 GW one in Tennessee and two 1.25 GW reactors in Georgia. In 2023, Texas alone installed 6.5 GW of solar power. Nitpickers will note that a gigawatt of “always available” nuclear power in hand is worth five gigawatts of “catch me when you can” solar power in the field, but since we’re blowing past a 100-to-1 ratio of new solar to new nuclear power installations, no one cares.

Nuclear power and pumped hydropower have historically been massive, complicated engineering projects that use lots of water. Solar and batteries can be scaled from hand-held (remember the solar-powered pocket calculators before cell phones?) to covering a roof to covering thousands of acres. Millions of people have the skills needed to design, install, and maintain solar electricity systems, which can be located anywhere the sun shines and require only small amounts of water to keep the panels clean. The moribund nuclear industry might shed its senescence and catch up to the blossoming solar industry, but I’m not betting on it.

Turning “I’m here whenever I feel like it” solar electricity into a firm “ready whenever you are” electricity is one reason batteries are the most important energy technology right now: we already know where to get all the energy we’ll ever need (from our sun) and how to collect it (using solar cells anywhere on the surface of our planet or in space). Now we just need to decide how to store electricity: whether to deploy mature technologies like pumped hydropower, lithium-based batteries, sodium-based batteries, or iron-based batteries or keep working on hydrogen and other ideas that haven’t made the jump from “we got it to work in our lab” to “works in the real world.”

Making Our Gadgets Go

Years ago, grandparents shopping for toys to delight their grandchildren and annoy their grandchildren’s parents might see “batteries not included” on the packages. That’s rarely the case nowadays: batteries are included in almost everything, from cell phones to laptops to cars. That’s the second reason batteries are the most important energy technology—more products need more batteries to work.

How Our World Makes Batteries

Let’s wade into the waters a bit to see what materials are actually in batteries today. Because they weigh less and last longer, lithium-based batteries are becoming the new standard. While alkaline, lead-acid, NiCad, and NiMH battery factories still exist, they are losing market share to the new battery factories that churn out rechargeable lithium-based batteries.

Mine Once, Recycle Forever

Lead is a heavy, toxic metal, but it’s also a recycling success story—from a materials-recovery standpoint (although not from a human-health perspective). One reason lead-acid batteries have been able to persist in places like car-engine starting systems is that we can recycle lead forever. An ounce of lead that we mined once in the 1860s is now part of the circular economy, used over and over again in batteries. The same thing will happen with lithium: once we mine and refine it, we’ll have it forever.

Lithium-based nickel-manganese-cobalt (NMC) batteries mix lithium with expensive and toxic metals. More affordable lithium-iron-phosphate (LFP) batteries ditch expensive metals for cheap iron. When the major patents on LFP batteries expired in 2022, our world was finally ready to move beyond the toxic-battery era. Now that manufacturers can make LFP batteries royalty-free, lead-acid batteries are being replaced by cheap LFP batteries for car-starting and deep-cycle marine application, and NMC batteries are being squeezed out of most electric vehicles.

Even cheaper sodium-based batteries, which just reached commercialization in 2024, are already replacing LFP batteries for super-affordable electric vehicles. As sodium battery factories ramp up production, it’s likely that they will replace heavier, more expensive, less reliable, shorter-lasting, and toxic lead-acid batteries. And for really large battery banks, we can use an entirely different technology called an iron-flow battery that lasts ten times longer than sodium batteries, making it more affordable and practical to store massive amounts of electricity for weeks or months.

A Deeper Dive Into Battery Chemistries
Batteries are a sandwich: two electrodes with an electrolyte in between. By convention, the positive electrode is called the cathode, and the negative, the anode. In a lead-acid battery, the cathode is lead-dioxide, the electrolyte is sulfuric acid, and the anode is metallic lead. In an LFP battery, the cathode is lithium iron phosphate, the electrolyte could be lithium hexafluorophosphate salt dissolved in an ethylene carbonate solvent, and the anode is typically carbon graphite. In a sodium-ion battery, the cathode is usually a Prussian blue analog (containing sodium, iron, carbon, and nitrogen), the electrolyte is often sodium hexafluorophosphate salt dissolved in a non-aqueous solvent like diethylene glycol dimethyl ether, and the anode can be expanded graphite or another carbon-based material.

Scientists are still experimenting, and manufacturers are still tinkering with the formulations for lithium-based and sodium-based batteries. It’s a bit nerve-racking for investors who have to put up billions of dollars to develop mines because no one is really sure how much lithium we’ll want. We might find that sodium-based batteries are good enough—and we don’t need any mines for sodium. We can get sodium chloride from seawater and use solar electricity to melt and zap that salt to obtain sodium metal.

Do We Have Enough Lithium?

But let’s assume we’ll want to keep making more and more lithium-based batteries, which theoretically, one day could be made light enough to replace jet fuel, a feat that sodium-based batteries can’t achieve. (Lithium has such great energy-storing potential primarily because it’s the lightest metal, having only three protons in its nucleus compared to sodium’s eleven.) Does our planet have enough lithium, and can we get it without destroying our environment?

We haven’t been looking that hard for lithium because until recently, we’ve been much more interested in gold, silver, uranium, coal, oil, and a long list of other materials, but so far, we’ve found over 22 million tons of it in six countries: Chile, Australia, Argentina, China, the United States, and Canada. That’s enough to make 2.8 billion electric vehicles using battery technology from 2020. If we keep looking for lithium, we’ll find a lot more of it. And as we keep developing battery technology, we’ll probably need a lot less of it than people were imagining when they thought lithium batteries were the only game in town.

Lithium is in salt in desert areas, such as in Chile and Nevada. The Silver Peak mine, about halfway between Las Vegas and Carson City, pumps up “brine” (water with a high salt content) to extract a few thousand tons of lithium chloride salt per year. Desert lithium brine operations can run entirely on solar power and have about the same environmental impact as fracking for natural gas (in terms of using water and disrupting local communities). But unlike natural gas, which is often burned once for energy and then persists in our atmosphere as carbon dioxide pollution, lithium can be endlessly recycled and used to store energy for us and countless future generations.

Lithium is also present in our Earth’s crust as lithium oxide in hard rock. In 2018, Mary and Gary Freeman discovered a lithium hard rock deposit in Newry, Maine, worth $1.5 billion. That deposit could be mined like a gravel pit: by backing up a gigantic electric backhoe and digging a big hole. The Maine legislature is working through the rules now to ensure that if someone decides to turn this block of rock into piles of batteries and wads of cash, they won’t leave a big mess behind. And in case you’re wondering if mine equipment can run on electricity, yes, it can. As electric vehicles and batteries get cheaper, it’s becoming relatively more expensive to operate a mine by burning fossil fuel than by installing solar panels and batteries.

Clean Batteries Are Our Future

So, I hope this insight has given you some positive perspectives to counteract the hand-wringing that so many people are doing about batteries. Yes, batteries used to contain toxic heavy metals like mercury, lead, and cobalt. No, they don’t have to, and most don’t anymore. Yes, we will need to mine for more lithium if we decide to build more lithium batteries. No, we don’t have to put all our eggs in the lithium basket—sodium batteries are better than the lead-acid batteries we’ve been using since the 1800s. There’s a good chance we’ll start building a lot more sodium-based batteries. For sodium, we don’t need any mines. Our oceans are full of sodium chloride, and our sun provides plenty of energy, which we can use to split salt into sodium and chlorine atoms. Once we have the materials we want to use for our batteries, then we can use sunshine to power our recycling facilities for a sustainable circular economy.

References and Further Reading