The demand for batteries keeps increasing as they are needed to support electrification of transportation and to store energy from sun and wind. Recent forecasts e.g., by McKinsey estimate a 6-fold increase in the Li-ion battery demand by 2030.

However, this might be an underestimation. I was yesterday listening to the Batteries Europe plenary session and Ilka von Dalwigk gave a very interesting presentation on behalf of EBA250, saying that the electric vehicle market size in 2022 was twice as big than forecasted in 2017. And for stationary energy storage, the market size was even four times bigger than estimated!

The Critical Raw Materials Act

One of the main challenges to respond to this demand is to ensure raw material availability in a secure and sustainable way. European Commission has recently published the Critical Raw Materials (CRM) Act to support this goal. First, it lists the critical and strategic raw materials. These are materials, which are economically important for Europe, but which have a high risk concerning their supply. The materials include lithium, cobalt, natural graphite, manganese, copper, and nickel, which are all used in batteries. Then, it proposes several important targets and methods to increase European production of such materials, and to improve resiliency when importing these materials from other continents.

What is not highlighted very much in the regulation, is substitution of the critical raw materials. It is only mentioned briefly in the communication about the CRM Act. However, developing substituting materials is very relevant as it is a method to reduce pressure on the critical material demand. These alternative materials will not fully replace critical materials, but they will be used in parallel. We must use CRMs only in such applications where they are truly required. Alternative materials can and should be used whenever possible.

Sodium is one part of the solution

There are several ways to reduce the demand for CRMs. We can utilise the side streams from mining more efficiently, reduce the scrap rate in processing by improved manufacturing methods, use batteries in a smart way or add self-healing methods to increase their lifetime, and of course recycle the battery materials from end-of-life batteries.

Lithium is and will remain an important battery material due to its superior energy density properties. However, utilizing more abundant materials in batteries is one part of the solution. And sodium, Na, seems to be the most promising alternative in near future. There is about 1000 times more sodium on Earth compared to lithium. It is also cheaper and more environmentally friendly to extract sodium from sea water, than to extract lithium from mines. Lithium is also available in brine, but in much smaller amounts than sodium. Thus, it is more expensive and energy consuming to extract lithium from brine, even though worth exploring.

Which materials are used in Na-ion batteries

The working principle in Na-ion batteries is the same as in Li-ion batteries. In a simplified view, only the charge carrier changes from Li-ion to Na-ion. When taking a closer look, there are some similarities, but also some differences in the materials.

The cathode materials can be very similar in Na-ion batteries and Li-ion batteries, as metal oxides can be used in both. Of course, Li is replaced with Na, but otherwise they are quite the same. These metal oxides may still contain CRMs, such as cobalt. A more sustainable option is to use Prussian blue analogues. These materials do not contain any CRM and are thus very promising. Also, vanadium-based cathode materials have been studied, but they might not be as attractive due to the high price and supply challenges of vanadium (vanadium is also on the CRM list).

The standard anode material in Li-ion batteries is graphite. Graphite can’t be used in Na-ion batteries since Na+, as a bigger ion than Li+, does not fit well between the ordered graphene layers in the graphite structure. Thus, hard carbon is used instead. It is less ordered and has larger spacing between the layers. One of the great opportunities with hard carbon is that it can be produced from locally available bio-based sources, such as lignin, which is a side stream from cellulose manufacturing. In comparison, graphite is either mined, or synthetically produced from fossil fuels.

A Li-ion battery uses copper and aluminium as current collectors. Copper is more expensive than aluminium, and it was also just added into the list of strategic raw materials, which might suffer from supply issues due to the huge demand. A Na-ion battery can use just aluminium as current collectors as sodium does not alloy with aluminium. Thus, no copper is needed, which will help to reduce their price. Aluminium brings also other benefits, such as the possibility to transport the batteries at 0V, which increases their safety. This is since aluminium is not prone to oxidation. On the other hand, copper will react (oxidise and dissolve) if the negative electrode potential rises too much, which might happen due to over-discharge or discharging to zero volts. For further details, I encourage you to read this very nicely written publication by Parth Desai et al.

Price of Na-ion batteries

In addition to the current collector and sodium itself, also other materials, such as the cathode components, can be cheaper in Na-ion batteries than in Li-ion batteries.

Processing methods are the same. Thus, Na-ion technology is a drop-in solution, which allows industry to use similar manufacturing lines without extra costs.

There are some estimations about the price of Na-ion batteries vs. Li-ion batteries. Academic reports estimated 15% reduction in price in 2018. On the other hand, recent announcements by industry predict as much as 50% cost reduction even compared to lithium iron phosphate (LFP) batteries, which have comparable energy densities than the best Na-ion batteries.

Applications of Na-ion batteries

Sodium is a bigger and heavier element than lithium. This means that the energy density of Na-ion batteries won’t reach the same level as the best Li-based batteries. This, and the lower price, makes them very well suitable for stationary energy storage applications where low cost is a must, but energy density does not need to be extremely high. Na-ion batteries will be one of the solutions (but not the only one) to enable better utilization of renewable energy, and it is thus important to secure their supply chains and manufacturing in large scale.

What will come faster to market, are electric vehicles that use Na-ion batteries as the energy storage. CATL has announced that they will install Na-ion batteries in mass-produced cars already in the end of 2023 in China. The range with one charging won’t be as high as with the best Li-ion batteries, due to the lower energy density. However, the predicted faster charging of Na-ion batteries will compensate this, as if it is possible to recharge the battery quickly, there might not be a need for a super high range. There are also plans to use a mixture of Na-ion batteries and Li-ion batteries in cars to find a balance between the cost and range.

Note that the increased charging rate (< 20 min) in Na-ion batteries is mainly due to the utilization of a hard carbon anode. Charge carriers can move faster in the disordered hard carbon materials, when compared to the highly organized and dense graphite that is nowadays used in Li-ion batteries. However, there are also research efforts to enable using hard carbon or other anode materials in Li-based batteries, which would allow fast charging also for those batteries. Thus, we will in any case have fast charging batteries in future.


I see a lot of potential for Na-ion batteries. As the need for energy storage increases, we need to use several battery chemistries in parallel to ensure that we have enough sustainably sourced materials for those. The sweet spot for Na-ion batteries could be a stationary storage with the capability to ensure storage in a few hours range. Li-ion batteries will be too expensive for this, and for longer duration (days/months), other options, such as pumped hydro, could be better.

In addition, based on the recent news from China, Na-ion batteries will be used also in cars already this year. There are also European companies (Altris, Tiamat, Faradion) that are developing Na-ion batteries for several applications.

If you want to learn more about Na-ion batteries, you can check this excellent seminar by Battery 2030+.