How much raw material is really needed for sodium-ion batteries? The scientific calculation, explained simply

Spoiler: no, the sea would not be desalinated if all the batteries the world needs were sodium-ion. Let's see why.

When talking about sodium-ion batteries, one of the most common objections is this: “If sodium comes from the sea, then to make enough batteries, you'd have to desalinate the oceans.”. It's a striking image, but it's wrong.

The reality is very different: Sodium is one of the most abundant, widespread, and accessible elements on Earth.. It is found in the sea, of course, but also in enormous salt deposits, in natural brines, and in an industrial supply chain that already handles gigantic quantities of sodium chloride today. For this reason, from the point of view of the availability of the raw material, sodium starts from a much more sustainable and scalable base than lithium, especially for stationary storage.

In other words: The challenge with sodium-ion batteries is not finding enough sodium. The challenge is to transform an abundant and inexpensive raw material into ever more efficient, durable, safe and industrialisable cells.

Why is this topic important?

The energy transition will require a huge amount of storage systems. With the increase in solar and wind power, the world will need batteries capable of storing energy safely, economically, and scalably.

And this is where a crucial question comes in: Are raw materials really enough?

For lithium, the issue is central. For sodium, however, the picture changes radically: Let's talk about an extremely abundant element, already present in huge industrial flows and distributed much more widely.. This is one of the reasons why sodium represents one of the most promising avenues for real large-scale storage sustainability.

How many batteries would the world need?

There isn't a single definitive number, because the future of storage will be composed of multiple technologies: batteries, pumped hydro, thermal storage, hydrogen, and other solutions. But to make a scientific argument, a reference scenario is needed.

We can use three simple levels:

• 1 TWh bulk accumulation: very large but still partial scenario
• 10 TWhhighly relevant global scenario
• 30 TWhA very ambitious global scenario for electrochemical storage

To understand the order of magnitude: 30 TWh means 30 billion kWh of installed capacity. It's a deliberately extreme scenario, useful precisely for testing the strongest possible thesis: if the world were to install tens of TWh of sodium batteries, would an unrealistic amount of raw material be needed?

The answer, as we shall see, is no.

To calculate the amount of sodium needed for 1 kWh, we need to consider the energy content of sodium in a battery. This depends heavily on the type of sodium-ion battery technology being used. Here's a breakdown of the basic physics and how you'd approach the calculation: **1. Energy Density of Sodium:** The fundamental concept is energy density, usually expressed in Watt-hours per kilogram (Wh/kg) or Watt-hours per litre (Wh/L). For sodium-ion batteries, the theoretical specific energy of sodium itself is a component, but the overall battery performance is determined by the complete electrode materials and electrolyte. * **Theoretical Energy Density of Sodium Metal:** If we were simply considering the pure energy potential of sodium metal as an anode material, we could look up its theoretical specific capacity and combine it with the voltage. * *Theoretical Specific Capacity of Sodium (Na):* Approximately 1166 mAh/g. * *Nominal Voltage of Sodium Electrode (vs. SHE):* Approximately -2.71 V (this is a standard potential, actual battery voltage will be lower due to other components). However, directly using these values for a practical battery is an oversimplification. Practical sodium-ion batteries use sodium compounds in the electrodes, and the overall cell voltage is crucial. **2. Practical Sodium-Ion Battery Energy Density:** For practical calculations, you'd use the energy density of a *complete sodium-ion battery cell* that uses sodium. This value is determined experimentally or through advanced modelling of the specific battery chemistry (e.g., using sodium-nickel-manganese-cobalt oxide (NNMC) cathodes, layered oxides, polyanionic compounds, etc.). * **Typical Energy Densities:** Current state-of-the-art laboratory-scale sodium-ion batteries can achieve energy densities ranging from **70-160 Wh/kg** (and sometimes higher for advanced prototypes). Commercial cells are often lower. **3. Calculation Steps:** Let's assume we have a sodium-ion battery with a known energy density. * **Target Energy:** 1 kWh = 1000 Wh * **Known Value:** Energy Density (E_density) in Wh/kg * **Calculation:** To find the mass of *the battery* needed for 1 kWh, you would use: Mass of Battery = Target Energy (Wh) / Energy Density (Wh/kg) *Example:* If your sodium-ion battery has an energy density of **100 Wh/kg**: Mass of Battery = 1000 Wh / 100 Wh/kg = 10 kg **4. Relating to Sodium Mass:** The 10 kg calculated above is the mass of the *entire battery pack* (including cathode, anode, electrolyte, separator, casing, etc.). The actual mass of *sodium* within that battery pack will be a fraction of this total weight. * **Identifying the Sodium Component:** Sodium is typically used in the anode, and its contribution to the total mass depends on the specific electrode formulation. The cathode material also plays a significant role in the overall battery chemistry and mass. * **Estimating Sodium Mass (Approximation):** Without knowing the exact battery chemistry and electrode composition, it's impossible to give a precise figure for the sodium mass alone. However, you *could* estimate it if you knew the percentage by weight of sodium in the active anode material, and the percentage of the anode material in the total cell mass. * Let's say the anode material itself is 20% of the total battery mass. * And within that anode material, the active sodium-containing compound makes up a certain percentage. If we consider a simplified scenario where a significant portion of the anode is related to sodium. This becomes complex rapidly if you're looking at specific compounds like NaFePO4 or Na3V2(PO4)3. **In summary, for a basic physical calculation:** 1. **Determine the energy density (Wh/kg) of a practical sodium-ion battery you are considering.** This is the most crucial and variable factor, dependent on the specific technology. 2. **Divide the target energy (1000 Wh) by this energy density to get the total mass of the battery per kWh.** 3. **To find the mass of sodium *within* that battery, you would need detailed specifications of the battery's internal composition**, which is not a simple "physical constant" calculation but rather an engineering detail of the specific battery. **Therefore, the amount of *sodium* needed for 1 kWh is not a single, fixed number but depends entirely on the efficiency and engineering of the sodium-ion battery technology used.** You are effectively calculating the amount of *battery* needed, and then the sodium content is a fraction of that.

To answer, one must start from physics, not from impressions.

In a sodium-ion battery, each ion No⁺ carries one elementary electric charge. One mole of sodium corresponds to approximately 26.8 Ah of transferable electric charge.

Assuming an average cell voltage of approximately 3.0 V, a mole of sodium can transfer approximately:

26.8 Ah × 3.0 V = 80.4 Wh

Since a mole of sodium weighs approximately 23 grams, the theoretical minimum of sodium to accumulate 1 kWh is

1000 Wh / 80.4 Wh × 23 g ≈ 286 g of sodium

For simplicity of explanation and to avoid underestimation, let's round it to:

0.30 kg of sodium per kWh of battery

This value isn't a marketing slogan, but a Order of magnitude physics. In practice, it can vary depending on the specific chemistry, active materials, cell design, and the sodium reserves present in the system, but the key point remains the same: The amount of sodium required remains surprisingly modest given the vast natural availability of the material..

Real numbers translation: from 1 TWh to 30 TWh

This figure indicates how much seawater that quantity of sodium would theoretically contain. It does not mean that this water would need to be treated with desalination plants.

Clear refutation: no, the sea would not be desalinated

It is essential to be very clear here.

Sodium batteries do not require desalination of seawater.

Desalination is a process designed to obtain Freshwater from saltwater. The battery supply chain, on the other hand, needs Sodium salts as a chemical raw material. They are two profoundly different things.

Saying that sodium “can come from the sea” does not mean that the world should build huge plants to extract salt from oceans for the sole purpose of making batteries. Industrial sodium can come from:

• sales gem rock salt
• Greeting natural
• solar evaporation
• Existing chemical and industrial flows

The correct representation is therefore not “a world that drains the sea”, but a supply chain that draws on vast salt resources, already used today by industry on a global scale.

What part of the salt supply chain would actually be needed?

Sodium chloride, that is common salt, contains approximately 39,3% in terms of mass. This means that to obtain 1 tonne of sodium, you need approximately 2.54 tonnes of NaCl.

Applying this ratio to the scenario 30 TWh, it would take about 22.9 million tonnes of salt.

It seems like a lot? Absolutely, yes. But on a global industrial scale, it's a number fully compatible with a large existing supply chain.

The crucial point is precisely this: Even in a highly advanced global scenario, the sodium needed for batteries represents a manageable quantity compared to global salt flows..

This is one of the reasons why, from a material perspective, Sodium is structurally more sustainable than lithiumnot because it requires “less chemistry”, but because it is based on an immensely more common, more accessible and less critical resource.

And how much sodium would theoretically be “taken” from the sea?

The sea water contains about 35 grams of salts per kilogram and sodium is one of its main components. On average, a concentration of approximately 10.8 grams of sodium per kilogram of seawater.

This means that One cubic metre of seawater contains approximately 11 kg of sodium.

So, for the scenario 30 TWh, we would need equivalent content in approximately 0.8 km³ of seawater.

This number must also be interpreted correctly:

• è tiny relative to the scale of the oceans;
• does not imply any “desalination of the planet”;
• it only serves to show that the amount of sodium involved is small compared to the available resources.

The real comparison to be made is with lithium

When assessing the sustainability of battery chemistry, it's not only electrochemical performance that matters. The material base is also important: where the elements are found, how widespread they are, how critical the supply chain is, how much the extraction weighs, how vulnerable the supply chain is.

And it is here that sodium shows one of its strongest advantages.

For lithium, a commonly used estimate is approximately 160 grams of lithium metal per kWh. Applying this value to 30 TWh in storage, it would reach approximately:

4.8 million tonnes of lithium

The point isn't to say that lithium will no longer be needed. The point is to understand the difference between two very different worlds:

• the sodium It relies on a vast, distributed, economical material base, already chemically present in enormous supply chains.;
• the lithium remains tied to a more delicate, geographically concentrated supply chain, more exposed to industrial and geopolitical tensions.

In summary: Lithium is lighter and more energetic per unit of mass, but sodium is much more abundant and much more natural to scale in terms of raw materials..

Why this really matters for sustainability

When talking about sustainability, one mustn't stop at the word “green”. One must ask: Can this technology be produced in large volumes without creating new critical dependencies?

In the case of sodium, the answer is much more encouraging compared to lithium, particularly for applications such as:

• residential property
• Commercial and industrial storage
• photovoltaic systems
• Electrical grids and utility scale

For these applications, the priority is not just to have the highest possible energy density. It is also to have:

• raw materials available
• greater cost stability
• more robust supply chains
• greater security
• a truly scalable technology in the long term

And this is where sodium can represent a more concrete form of sustainabilitynot theoretical, not just environmental in a narrative sense, but Industrial, material and systemic.

The scientific conclusion

If the world installed tens of TWh of sodium-ion batteries, We shouldn’t desalinate the sea and we wouldn't be faced with a problem of intrinsic raw material scarcity.

We should instead do what all great technology requires:

• industrialise production
• Refine materials
• optimise cell chemistry
• Improve processes, electronics, BMS and system integration

That's the crux of it: The challenge with sodium isn't the abundance of the resource, but the maturity of the technology..

In summary: Sodium isn't interesting because it “comes from the sea”, but because it is based on an extraordinarily abundant, widespread raw material that is already available on an industrial scale. For this reason, in the long term, it represents one of the most solid bases for truly sustainable storage.

Final question: will the real sustainability of storage come from sodium?

For some very high energy density applications, lithium will continue to be central. But when the topic is to store so much energy safely, accessibly, reproducibly and on a global scale, sodium has a very strong argument in its favour: The raw material isn't the problem.

And this is precisely why more and more attention is shifting towards sodium-ion batteries: not as a technological curiosity, but as a serious contender for making energy storage more resilient, more democratic, and more sustainable for the planet.