Sodium-ion batteries

The development of next-generation batteries is crucial to the future of energy storage, which is key to electrification and to making renewable energy production more flexible and ensuring its integration into the grid.

Since their introduction in 1991, lithium batteries have dominated the energy storage sector. However, this dominance has led to a significant increase in demand for this mineral, a trend that shows no sign of abating. Consequently, concerns have been raised about a potential shortage of lithium supplies, with resulting price rises and delays due to supply shortages.

In recent years, battery manufacturers and the automotive industry have been exploring alternative raw materials to lithium for the manufacture of energy storage systems with a view to stabilising supply and demand. One of the most viable options is the sodium-ion battery: the relative abundance of this mineral and its low cost make it a key alternative for renewable energy storage.

What are sodium-ion batteries and how do they work?

Sodium-ion batteries are a type of rechargeable battery that carry an electric charge using sodium ions (Na+) instead of lithium ions (Li+). Sodium is a soft, silvery-coloured alkali metal that is very abundant in nature – it can be found, for example, in sea salt or in the Earth's crust. Sodium-ion batteries work in much the same way as lithium-ion batteries, as the chemistry of both elements – being alkali metals – is similar.

Researchers first studied sodium batteries in the 1980s, but it was not until the 21st century that they rediscovered sodium's true potential for energy storage.

According to a study on the patent landscape for these batteries, published by the consultancy firm Cypris in 2026, researchers have recorded more than 50% of patented research activity in the field of sodium-ion batteries in China (65%), followed by the United States (5%) and Japan (4%). Europe is also beginning to make progress in this field. The companies currently playing the most significant role in this technology are the Chinese firms CATL, BYD and HiNa.

The future looks promising in this regard. The International Energy Agency forecasts that by 2030 the production capacity for sodium-ion batteries will be 590 gigawatt-hours, almost six times its current capacity. Researchers and manufacturers can achieve this projection if they accelerate technological improvements and make progress in manufacturing using equipment similar to, or the same, as that used for lithium batteries.

How do sodium-ion batteries work?

These batteries consist of the following components: a negative electrode, or anode, from which electrons are released, and a positive electrode, or cathode, which receives them. When the battery is discharged, sodium ions move from the anode to the cathode through an electrolyte – a substance composed of free ions that acts as an electrical conductor – creating the potential difference that generates the current. When the battery is charged, the sodium ions return to the anode until a predetermined end-of-charge voltage is reached.

One of the differences between lithium and sodium batteries is their energy density. This refers to the amount of energy they can store per kilogram. Lithium batteries can store more energy than their sodium counterparts. Scandium doping enables sodium-ion batteries to increase their energy density to more than 200 watt-hours per kilogram, making them ideal for applications where battery volume is less of a concern, such as electric vehicles with limited range and stationary energy storage for electricity networks.

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Manufacturing sodium-ion batteries

There is a paradox regarding the manufacturing costs of sodium-ion batteries. Although sodium is a more abundant and cheaper material than lithium, the lack of a well-developed supply chain drives up the cost of the infrastructure, the cooling system, the electrical components and the assembly process.
  
 Most current sodium-ion technologies use the same processes as lithium batteries, which represents a very significant advantage over other storage technologies currently under development. Sodium technology thus benefits from all the economies of scale and knowledge derived from lithium.

Advantages and challenges of sodium-ion batteries

The paradigm shift from lithium-ion to sodium-ion batteries opens a range of opportunities for large-scale electrification and brings with it a number of advantages:

• Abundance and accessibility of raw materials: They use sodium, an alkali metal found in large quantities in the Earth's crust and in sea salt, ensuring a virtually inexhaustible supply.
• Reduced reliance on critical minerals: By replacing lithium and cobalt, the risks of shortages, strains on global supply chains and vulnerability to price volatility of scarce metals are reduced.
• Reduced long-term economic costs: Although manufacturers are still adapting the production infrastructure, the low cost of the base material will significantly reduce the cost of energy storage once the supply chain is established.
• High safety and thermal resistance: They exhibit high chemical stability and operate efficiently in extreme temperature conditions (both cold and hot), thereby reducing the risk of overheating or fire.

However, to make the most of this breakthrough, a number of challenges need to be overcome:

• Lower energy density compared to lithium: As they can store less energy, they require larger batteries to deliver the same capacity, which limits their use in electric vehicles with a long range.
• Supply chain in its infancy: Suppliers, large-scale industrial extraction and components specific to this technology are still at the research and development stage.
• Need to scale up industrial production: To compete on price and volume, factories must adapt or expand their mass assembly lines, a process requiring significant capital investment.
• Lower commercial adoption and market maturity: Compared with lithium technology, which is well-established after decades of widespread use, sodium still has limited commercial deployment and fewer products available on the current market.

Sodium-ion battery storage and electrification

The potential of sodium-ion batteries lies in their storage capacity when coupled with renewable energy parks and in their ability to support existing electricity networks. In this way, they can ensure the stabilisation of energy supply and demand and be integrated into an electrified system to increase its efficiency, thereby facilitating the management of residential and industrial self-consumption. This alternative is well suited to solutions where weight and volume are less critical than cost, safety and system availability.

The future of sodium ion technology

Research into lithium-ion batteries over recent years has benefited the development of sodium-ion batteries. As this type of energy storage shares several similarities with lithium-ion batteries, it has seen particularly rapid progress and promises to be a key advantage in its deployment.

Furthermore, the growing demand for large-scale electrical energy storage and recent discoveries – such as the use of hard carbon as an anode material – are driving the continued development of sodium-ion batteries.

The major challenges they face open three main avenues for technological improvement:

• Increasing energy density to improve energy storage.
• Promotion of high-cycle-life cells (fast charging, frequency regulation, regenerative braking in electric vehicles).
• Hybridisation with lithium batteries. Some manufacturers are developing hybrid packs for electric vehicles that combine lithium cells (energy reserve) with sodium cells (better performance in fast charging).

This technology is not expected to replace lithium-ion batteries, but rather to complement them in hybrid systems or to be applied in sectors sensitive to the prices of conventional batteries. There are already electric vehicle manufacturers opting for hybrid batteries. These could reduce range loss in cold winter temperatures as well as lower vehicle manufacturing costs – once the sodium battery supply chain is in place – without compromising performance.

The exclusive use of sodium-ion batteries targets products where energy density is not an issue. On the one hand, this includes light vehicles where they replace lead-acid batteries. On the other, in stationary energy storage where safety and cost are more important than energy density. BloombergNEF forecasts that the demand for stationary energy will be up to 20 times higher by 2030.

Thanks to sodium-ion batteries, electric mobility can be cheaper, more resilient and independent of the fossil fuel supply chain. Once the challenges have been overcome, the next objective will be to commercialise this technology at low cost and on a large scale.