Beyond Lithium: What Will the Next Generation of Batteries Be Made Of?

Lithium-ion batteries have taken up permanent residence in our homes for years now. They're hidden in your phone and laptop, but they might also lurk in your electric toothbrush or your bike. Even bigger lithium-ion batteries are vital for electric vehicles. Massive lithium batteries are even deployed on the power grid, helping even out the peaks and valleys of electricity generation and demand. These batteries also play a huge role in the transition away from fossil fuels, a key driver of climate change. 

Lithium-ion batteries power our lives and the demand for them grows more and more each year. It raises the question: Do we have enough resources to meet the demand? And could anything ever replace lithium-ion batteries? 

Scientists have seen this issue coming for years.   

"The concern is, do we have enough resources to make all these lithium-ion batteries for every application? That's part of the drive for the US government is to be thinking long term about other chemistries," Vincent Battaglia, head of the Electrochemical Technologies Group with the Lawrence Berkeley National Laboratory, told CNET.

Here's a look at the concerns scientists have with lithium-ion, and what could replace it.

Why are lithium-ion batteries so popular?

What makes lithium so great? There are three answers: energy density, cycle life and cost. 

Lithium-ion batteries are currently the most energy dense batteries we have on the market. Energy density is the amount of energy you're able to store in a given amount of space. 

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"You can have devices that have lots of energy, but take up very little space and weight," Battaglia said. "Those are very useful for when you want to carry things around like cell phones and laptops and other personal devices and all the way up through electric vehicles."

Lithium-ion batteries also win the popularity contest because they're rechargeable, but there's more to it than that. They have a relatively long cycle life, which is one of the ways manufacturers measure how long the battery will last. Think of it as a way of measuring just how rechargeable your battery is. 

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As with anything else, price is also important. These batteries have become relatively cheap to manufacture and produce. This is partly due to the low cost of the raw materials necessary to make the battery. And as these batteries continue to grow in mass production, the cost of manufacturing continues to get cheaper as well. 

Battaglia said the large volumes at which these batteries are produced have cut the costs quite a bit. But it wasn't always this cheap. 

"The price of lithium-ion batteries initially when they started on the market wasn't that cheap compared to the other competitors," Eungie Lee, a materials scientist at Argonne National Laboratory, told CNET. "But the price has been dropping down significantly over the past decade."

Materials scientists and engineers have been improving the manufacturing process of lithium-ion batteries for years. Scientists have found chemically compatible and cheaper materials, while engineers continue to pack more of those materials into the same space, according to Lee.     

The problems with lithium batteries  

Despite the relative efficiency and affordability of lithium as a battery chemistry, there are some issues with these batteries' widespread adoption.

Lithium battery safety concerns

The biggest safety issue with lithium-ion batteries by far is the risk of it catching fire. Lithium-ion batteries rely on a liquid electrolyte solution in order to charge and discharge the battery properly. It does this by moving lithium ions between the positive side (cathode) and negative side (anode) of the battery, acting as a middle man of sorts. The problem is that this electrolyte is flammable. 

Lithium-ion batteries don't play well with heat. If a battery cell starts to overheat, pressure will build up within the cell and open the pressure release port, Battaglia said. These release ports are to help release the pressure and keep the battery from exploding. However, what gets released is a flammable gas vapor that could potentially catch fire. This spreads to the other battery cells and forms a chain reaction. 

"We call it thermal runaway," Lee said.

The actual likelihood of a lithium-ion battery catching fire is extremely low. But it does happen. Fires caused by lithium-ion batteries have been on the rise in New York in particular, with e-bikes and scooters posing the biggest risk. These fires are dangerous and can spread quickly. It's also why there are some specific regulations around taking batteries on airplanes.

Lithium comes at a cost

Lithium-ion batteries are great and all, but the process of actually mining the lithium carries some downsides for the environment and areas where it's extracted. This is mainly due to the water and energy resources needed during the process. 

Much of the world's lithium supply is mined in Chile and Australia. During the mining process, lithium is extracted from salty water brines found underground or on the surface. The liquid is pumped from the earth and divided into large pools and left to sit so the water can evaporate, leaving behind lithium and other materials.          

In a way, lithium mining pollutes our air and water. The mining process takes up precious land and water resources. And while lithium has become an important part of the transition to renewables, most of the equipment necessary to operate the lithium mines are powered by fossil fuels. 

Other metals in lithium batteries

While lithium is obviously the main element of a lithium-ion battery, there are other materials and metals in these batteries. Nickel and cobalt in particular have been used in many lithium-ion batteries, especially those in electric vehicles. Nickel is used to increase the energy density of the battery and cobalt is used to stabilize it, Lee said.

However, increasing the nickel content in the battery can only increase the battery's energy density by so much. Nickel and cobalt can get pretty pricey too. But it's not just money that we should be worried about: There's a human cost. Most of our world's cobalt is mined in the Democratic Republic of Congo by people who work in inhumane conditions and breathe in toxic dust from the cobalt.

Now, scientists at the Argonne National Laboratory are working on how to use manganese as a sustainable alternative to expensive cobalt. Argonne researchers say manganese is much more affordable than cobalt. It's also a widely abundant resource and is a safer alternative than a battery packed with high concentrations of nickel. 

"We are working on how to increase manganese, get rid of the cobalt and decrease nickel content," Lee said.

A promising alternative in sodium

Lithium-ion batteries aren't going away any time soon, at least for the next decade or so. Scientists have been well aware of the safety and sustainability risks associated with lithium-ion batteries for years. But developing new chemistries isn't easy, and lithium is hard to compete with. The good news is that US scientists have begun exploring a promising new alternative in sodium-ion batteries. But this comes with its own set of challenges.  

"The biggest advantage is just the sodium itself. Compared to the lithium, it's much more abundant, and cheaper," Lee said. "It's everywhere." 

Sodium-ion also opens up new opportunities for scientists to experiment with new elements and materials that didn't play nice with lithium. This allows for the increase in manganese and iron content in the battery cathode. Both of which are cheaper and more sustainable than nickel and cobalt. 

The liquid electrolyte solution that's used in lithium-ion batteries has posed a fire risk in many homes. And while the current version of sodium-ion battery technology still has the same safety concerns, Lee says that the chemistry of sodium allows for the development of potential new non-flammable electrolytes, potentially even new solid-state electrolytes. 

Sodium-ion batteries aren't perfect. The biggest downside facing these batteries is its lower energy density and weight. Sodium is bigger, heavier and can't quite compete with the energy density of lithium-ion just yet. If we were to use sodium-ion batteries in electric vehicles, the lower energy density and added weight of these batteries would mean shorter driving range. The cycle life of sodium-ion batteries is also lower than that of lithium-ion batteries, and capacity degradation in sodium-ion batteries happens more quickly. In other words, the lifespan of sodium-ion batteries is noticeably shorter than lithium. 

"That's why about 10 years ago when the lithium-ion batteries were taking off, sodium-ion batteries didn't get much real attention from the industry," Lee said. "But now I see there's a huge interest in sodium-ion batteries."

In its current state, sodium-ion batteries have limited applications, and still have a ways to go before they ever reach a mass market. However, scientists will continue exploring even more new possibilities that sodium can bring.