If you buy a smartphone, an electric car or an electric shaver in 2026, they will most likely contain lithium-ion batteries. These batteries are compact and powerful because of their high energy density. However, lithium mining comes with a wide range of environmental consequences, and few countries have sufficient lithium deposits. Scientists have therefore been researching an interesting alternative since the 1970s: sodium-ion batteries.
A study by the Fraunhofer Institute and the University of Münster has investigated various materials used in the construction of sodium-ion batteries. Taking into account new developments in the battery market, the researchers concluded that sodium-ion batteries are on the verge of market readiness.
As a component of table salt, sodium is significantly easier to extract than lithium and is available in large quantities. So are these innovative batteries the solution for green mobility?
What has changed with salt batteries in recent years?
The study describes two developments in the manufacture of sodium-ion batteries. We reported on salt batteries just a few years ago. As we noted at the time, the energy density—that is, the amount of energy a battery could store—was still between 5 and 15 percent lower per unit of weight compared with lithium-ion batteries. However, the new study shows a different conclusion. “Depending on the cell chemistry, the energy density and carbon footprint can differ considerably in some cases,” the authors write. In other words: salt batteries aren’t necessarily less powerful than lithium-ion batteries. With the right materials, they can achieve a similar energy density.
The team was led by Philipp Voß, a research associate at the Fraunhofer Institute. They came to this conclusion using a new and particularly comprehensive modelling approach based on real industrial production data. The analysis was carried out on the scale of so-called ‘gigafactories’. These factories have a production capacity in the double-digit gigawatt-hour range. The study also focused on energy density and the carbon footprint.
The Chinese battery manufacturer CATL is receiving major orders of their sodium-ion batteries. This shows there is already demand for mass production. Researchers at the Fraunhofer Institute attribute this demand in part to how easily existing production lines can be adapted. As lithium-ion and sodium-ion batteries have a similar design, companies can easily adapt their existing production lines. This lowers the barriers to market entry and accelerates production.
Market readiness is set to give a further boost to materials research
According to the Fraunhofer study, this growing demand for sodium-ion batteries and the increase in production could soon offset the technology’s drawbacks. Through “targeted material optimisation”, manufacturers could further reduce the gap in energy density. Battery cells with layered oxide cathodes are particularly promising, as they exhibit the highest energy density of the cells examined.
Furthermore, the use of hard carbon makes the battery cells particularly environmentally friendly compared with the synthetic graphite used in lithium-ion batteries. When used as an anode material, hard carbon currently still has a “significantly lower specific energy than graphite”. However, the study suggests that targeted improvements to the material could further enhance its energy density in the future.
Let’s summarise these rather technical findings: thanks to large-scale contracts and modern materials, sodium-ion batteries are becoming an even more promising sustainable alternative to lithium-ion batteries than they were a few years ago. The flexibility of supply chains could further accelerate this development in the coming years. So the only question that remains is: just how great is the potential for greener electric mobility?
Assessment by Michael Reckordt from the PowerShift association
To find this out, we asked Michael Reckordt from the PowerShift association. The Berlin-based association stands for an energy sector that is both environmentally friendly and based on solidarity. It examines, amongst other things, issues relating to energy and raw materials policy. Michael supports the PowerShift team in the key areas of ‘the raw materials transition, the circular economy and EU legislation’.
“If sodium-ion batteries were to really take off on the market,” Michael told RESET, “that would certainly have consequences for some raw materials.” As these batteries become more commercially viable, global demand for lithium, cobalt, manganese and nickel would fall. And all these materials are “associated with major challenges in their extraction. These include high water consumption and serious water pollution in Indonesia and South America, and land-use conflicts in South Africa. In the Democratic Republic of Congo, the challenges even extend to child labour.”
Sodium consumption would inevitably rise, although this would largely pose no problem. The situation is different, however, when it comes to the use of aluminium, “which is fraught with environmental and social conflicts”.
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“Sustainable mobility,” Reckordt continued, “requires more than just a shift in propulsion systems”. According to the raw materials expert, “the battery in a vehicle accounts for only around 20 to 25 percent of its weight”. Raw materials such as cobalt, nickel and manganese would still need to be used by bodywork manufacturers, for example, in the refining of steel. Sodium-ion batteries would therefore merely represent an “improvement on the status quo”, but not the solution for a green mobility transition.
We’ve explored what a successful mobility transition might look like in more detail in our Green Book. Among other things, it became clear that we need to move away from private car travel and adopt a more multimodal approach. After all, transporting 50 people by bus or train, rather than in 50 separate cars, ultimately saves significantly more raw materials than advances in battery technology.
