Sodium-based batteries could solve the lithium crunch

Lithium gets most of the attention when it comes to battery technology, but its downstairs neighbor on the periodic table could eventually displace it.

Sodium-ion batteries are garnering attention as technological advancements suggest that, compared to lithium-ion batteries, they could achieve similar performance in a wider range of applications, all without the supply chain headaches. Rising demand for batteries has caused the price of lithium to skyrocket—it’s up nearly 450% compared with last year, according to S&P Global Commodity Insights.

Sodium, meanwhile, “has almost unlimited supply,” Jason Zhang, a pioneer in battery research and lead author of a recent DOE lab report on a sodium-battery breakthrough, told Emerging Tech Brew.

Like any battery chemistry, sodium-ion comes with its own tradeoffs. And although some companies—like CATL—are exploring near-term commercialization, Zhang said the technology will need several years to both reach maturity and for production to scale.

Stable salt

Sodium is more abundant than the metals used in lithium-ion batteries, which makes it less expensive and more environmentally friendly to source. The concentration of sodium in the Earth’s crust is ~500x that of lithium, and it can also be extracted from seawater.

Sodium-ion batteries are also safer because they are nonflammable and less susceptible to temperature changes than lithium-ion batteries.

The biggest downside is that sodium-ion batteries have a lower energy density than lithium-ion batteries. This means an EV with a sodium battery that’s the same size as a standard lithium-ion battery would not be able to travel as far on a single charge. And to make matters more challenging, packing more voltage into the same space causes sodium-ion batteries to break down faster.

Researchers, including Zhang and his team at the DOE’s Pacific Northwest National Laboratory, are working on extending the life of sodium-ion batteries and improving energy density to achieve performance that’s more in line with lithium-ion cells today. Research they published in June brought that goal one step closer to reality. Zhang and the PNNL team developed a sodium-ion battery with a combination of materials that increased the lifespan over previous iterations.

The key difference in their new battery is the electrolyte—the part of the battery in between the negative anode side and positive cathode side that allows ions to pass back and forth as the cell charges and discharges energy. As a battery reaches the end of its useful life, the electrochemical reactions that keep those ions flowing slow down, stopping the battery from recharging. This process happens much more quickly in current sodium-ion batteries than in lithium-ion batteries.

The PNNL team found that a different liquid solution and a specific kind of salt create a new electrolyte that enables a longer life cycle than most sodium-ion batteries previously reported.

“For sodium batteries, when you increase the voltage, the electrolyte is much less stable. So the conclusion of this work is we developed an electrolyte which is very stable even at higher voltage,” Zhang said.

Looking ahead

Chinese battery giant CATL could begin making sodium-ion batteries as soon as next year, and a number of startups are also working on increasing manufacturing capacity for sodium-ion production. UK-based Faradion has been focused on sodium batteries since 2011. HiNa Battery Technology in China, Tiamat in France, Altris AB in Sweden, and Natron Energy in the US are all commercializing sodium-ion tech as well.

In the short term, sodium-ion batteries could be used for applications that require lower energy density, longer-lasting batteries—such as stationary storage—potentially easing some of the supply constraints on raw materials for the lithium-ion batteries needed for EVs.

Researchers will continue to work toward improving the energy density and stability of sodium-ion batteries, Zhang said. When sodium-battery tech is fully developed, it should be able to power light-duty EVs along with energy storage systems, according to some experts.

The PNNL team is also focused on improving the anode and the cathode in their sodium-ion battery, Zhang told us. The goal is to identify materials that would improve the anode and could eliminate cobalt in the cathode.

But getting this new sodium battery from the lab into commercial production could take five to 10 years, Zhang estimated. He said the lab doesn’t yet have a commercial partner, but it’s “actively looking for industry partners” to commercialize the tech.

“Sodium batteries still need significant work. So we don’t want people to think this is ready-to-use technology. [We] still have a lot of work to do before commercialization,” he said.