How Does a Sodium-Ion Battery Work and Its Difference From a Lithium One

With the world shifting towards renewable energy, the method of storing such energy effectively and at a reasonable cost is gaining significance. Although the lithium-ion battery has served as a primary battery over the past years, the sodium-ion battery is emerging as an environmentally friendly alternative with reduced costs.

Their cost-effectiveness and sustainability make them attractive for renewable energy storage, electric vehicles, and off-grid power systems. This post will share how a sodium-ion battery works, its key components, advantages, limitations, applications, future potential, and practical alternatives.

What Is a Sodium-Ion Battery?

A sodium-ion battery, SIB, or Na-ion battery is a rechargeable device. Energy is stored in the battery through shuffling sodium ions back and forth between two sections known as the cathode and anode. It functions pretty much the same as a lithium-ion battery (LIB). However, it contains the sodium element rather than lithium to move the charge. The role of a sodium-ion battery is as follows:

• Discharging: Sodium ions move back and forward between the anode and the cathode via the electrolyte. This causes current flow through a circuit to provide electricity.
• Charging: This pushes back the sodium ions to the anode, and the external power source stores electricity.

What Differs a Sodium-Ion Battery From a Lithium-Ion One?

Sodium-ion and lithium-ion are not merely a case of exchanging one metal with another. Their differences are found in operation, cost, and application, among other features. Here's a detailed comparison of both batteries:

1. Charge Carrier: SIB batteries charge transfer with the help of sodium ions, and LIB batteries charge transfer with the help of lithium ions.
2. Availability and Cost of Material: Sodium is abundant and cheap due to an abundant source supply, such as salt, whereas lithium is rarer and concentrated in certain parts.
3. Ion Size & Mobility: Sodium ions are larger and move slower reducing the density of energy. Unlike lithium ions, which are smaller and have the ability to travel and accommodate energy more readily in an equal space.
4. Voltage Operating: Sodium-ion batteries use approximately 3.0 V, whereas lithium batteries use approximately 3.7 V, which provides more energy output.
5. Electrode Materials: SIBs utilize materials such as layered oxides, Prussian Blue Analogs, and polyanionic compounds. Conversely, LIBs make use of layered oxides, spinel, and phosphates. Sodium batteries employ hard carbon or alloy-based anodes, as opposed to lithium batteries that mostly employ graphite or silicon.
6. Electrolytes: All batteries are powered by an organic solvent. The distinction is that SIBs use sodium salts, whereas in LIBs, there's the use of lithium salts.
7. Energy Density: Dense batteries like SIBs have a lower energy density of 100-200 Wh/kg. Instead, LIBs contain far higher energy density (200-260 Wh/kg) and thus are more appropriately used in small gadgets and by electrically powered vehicles.
8. Safety and Thermal Stability: The temperature of SIBs is much less susceptible to overheating when compared to an LIB that needs more critical handling.
9. Cost & Supply Chain: A Na-ion battery is cheaper as it does not use costly metals such as cobalt and nickel like the lithium one.
10. Applications: SIBs can be used for grid storage and low-demand vehicles. But when it comes to high-performance electric cars or even appliances, then it's lithium where it's at.

Crucial Components of a Sodium-Ion Battery

There are four components of sodium-ion batteries, among which every part defines the performance, safety, and efficiency of the battery:

1. Anode

It's the negative side of the battery that holds sodium ions when charged and releases them when used. Here are the usual materials used in the anode:

• Hard Carbon (Most Common): It is a type of disorganized carbon that has a greater space between layers and can absorb sodium ions efficiently (as is not the case with graphite). Hard carbon has moderate capacity (250-300 mAh/g) and long-term stability, but it's inferior to lithium-ion's graphite anode capacity.
• Alloy-Based Anodes (Tin, Phosphorus, Antimony): These store considerably more (e.g., up to ~2596 mAh/g in phosphorus). But then they swell enormously when in use, deforming and cracking the anode, and shortening its lifespan. They necessitate peculiar designs, such as nanostructures or composites, so that they would become more stable.
• Titanium-Based Oxides (Na₂Ti₃O₇, TiO₂): These are very stable and safe, and display very low volume change during the cycling, thus they have a long life. Nevertheless, they have reduced capacity (150-200 mAh/g).

2. Cathode

It's the positive side of the battery that takes in sodium ions when discharging and releases them when charging. These are the frequent materials used in the cathode:

• Layered Transition Metal Oxides (NaₓMO₂): They include NaFeO₂, NaNiO₂, and NaMnO₂, which achieve good performance and are of high-capacity (100-200 mAh/g). However, they're susceptible to high-voltage instabilities.
• Prussian Blue Analogs (PBAs): Contains an open structure based on iron materials that allows the rapid movement of sodium ions. They are cheap and exhibit a high stability, yet they store less energy (90-120 mAh/g).
• Polyanionic Compounds (NaₓFePO₄, Na₃V₂(PO₄)₃): Besides being associated with an outstanding heat stability and a long life, they possess low conductivity and hence require a carbon coating to achieve efficiency.

3. Electrolyte

These let sodium ions pass between the anode and cathode but block electrons. There are two types of electrolytes in a Na-ion battery:

• Liquid Electrolytes: Made from sodium salts like NaPF₆ or NaClO₄ in organic solvents (EC, PC, DMC). They conduct ions well (~10 mS/cm) but are flammable, like in lithium batteries.
• Solid-State Electrolytes: Ceramics (Na-β-alumina) or polymers could be utilized. Less flammable and safer, they have slower ion conductivity (~0.1-1 mS/cm).

4. Separator

A Na-ion battery typically uses Porous Polymer Films (PP, PE, or Ceramic-Coated) as a separator between the anode and cathode. This is to guarantee that contact between them cannot cause a short circuit and still pass ions through. The separator switches off under hot conditions to protect the battery, as well as it does not suffer damage under chemical attack by sodium electrolytes.

How Sodium-Ion Batteries Function?

The mechanism of SIBs is one of shuttling of sodium ions between the anode and cathode. Here's how charging and discharging happen in them:

1. Discharging (When the Battery Powers an Appliance)

Step 1: During the usage of the battery, sodium ions (Na⁺) are released into the electrolyte by moving out of the anode. Thus, discharges electrons as a result.

Step 2: The negatively flowing electrons at the anode (e⁻) are moved to the cathode through an external circuit and create electricity to flow through the device.

Step 3: The separator enables the ions to pass unscathed between the electrodes without contacting.

Step 4: These (Na⁺) ions would move through the electrolyte to enter the cathode structure.

Step 5: When the Na⁺ ions are incoming, the positively charged cathode (e.g., NaₓMO₂) collects them and gives off energy in the form of electricity.

Anode: Na → Na⁺ + e⁻ (oxidation).

Cathode: Na⁺ + e⁻ + MO₂ → NaMO₂ (reduction).

2. Charging (When the Battery Stores Energy)

Step 1: When charging an SIB battery, the external power pumps the electrons out of the cathode and to the anode.

Step 2: At the same time, the positively charged Na⁺ ions are pushed out of the cathode material into the electrolyte, and the released electrons flow through the outer circuit.

Step 3: The separator prevents the electrodes from touching while allowing sodium ions to flow freely.

Step 4: The Na⁺ ions rush through the electrolyte and are stored in the anode to provide energy.

Cathode: NaMO₂ → MO₂ + Na⁺ + e⁻ (oxidation).

Anode: Na⁺ + e⁻ → Na (reduction).

source: ElectronicsWeekly

Strengths and Limitations of SIB Batteries

The fact that SIBs are a potential substitute for LIBs does not imply that SIBs are without any issues of their own. There are dual sides to them. Here are their strengths and limitations:

Strengths

• Low Cost & Abundant Materials: Salt or seawater is the source of sodium, which is hundreds of times plentiful than lithium. It does not require metals such as cobalt or nickel. This makes SIBs less expensive, less prone to supply problems, and perfect for employing in large-scale applications, such as grid storage and cheap electric vehicles.
• Performs Better in Cold Weather: Tends to operate well in low temperatures, with less chance of electrolyte freezing, and also functions well in rough environmental conditions.
• Safer Operation: Sodium is not reactive and reduces the risk of fire and explosions. The electrolytes are more stable and do not present lithium plating, which is a typical pitfall with lithium batteries.
• More Sustainable: Can be easily recycled with a lesser effect on the environment, as sodium is very abundant, and mining is less destructive.

Limitations

• Reduced Energy Density: Measures levels of up to 30 or 40 percent less energy than lithium batteries (100-200 Wh/kg vs 200-260 Wh/kg). This means that they are bulkier and heavier and therefore are yet to be perfect in high-performance EVs.
• Shorter Life Cycle: Present SIBs currently have short cycle lives of roughly 1,000-3,000 compared to 3,000-5000+ cycles in LIBs. Problems heard of include wear on the cathode and anode instability, with hard carbon still not being graphitic level in lithium batteries.
• Scaling & Manufacturing Limitations: The production is not fully developed yet, and lithium batteries control the market. In addition, there is a need to have superior materials and designs, as well as the already established factories and R&D that are lithium-friendly.
• Electrolyte & Interface Issues: Even the protective film of electrodes is not stable and shortens the life span. Also, stronger sodium electrolytes are needed, especially for solid-state designs.

Applications & Future Potential of Na-Ion Batteries

Sodium-ion batteries are now emerging as an increasingly viable substitute to lithium-ion batteries, where low cost, safety, and sustainability outweigh the desire to maximize energy density. Take a look at how they are currently being used, and can be used in the future, and how they're being improved:

Current & Near-Term Applications

1. Stationary Energy Storage

The low price, long usage life, and temperature resistance make SIBs suitable for storing renewable energy on a large scale. They're already used in big projects like HiNa Battery's 100MWh system in China. Their operation at very low temperatures (down to -40 °C) requires their use as a backup power source in off-grid locations and data centres that need a secure source of power.

2. Small-Scale & Residential Storage

They're being tested in microgrids and community power systems, especially in places with limited lithium supply. Companies like Natron Energy are creating safe, non-flammable SIB home storage solutions.

3. Electric Vehicles (Pilot Use)

SIBs are being tried in low-cost EVs, small city vehicles, and fleets. CATL's latest battery version (175 Wh/kg) claims to add over 500km of range in EVs in just 5 minutes of charging. Hybrid packs combining SIBs and LIBs are also in development, giving good cold-weather performance alongside higher energy density.

Research Efforts to Boost Energy Density

1. Advanced Cathode Materials

Researchers are improving layered oxides like NaₓMnO₂ to boost voltage and capacity, with Princeton developing more stable, conductive versions. Prussian Blue Analogs are being redesigned to prevent gas release at high temperatures. Also, NaSICON-type cathodes have reached 458 Wh/kg, about 15% higher than earlier SIBs, due to a breakthrough from the University of Houston.

2. High-Capacity Anodes

New hard carbon designs, including alloy doping, are approaching 300 mAh/g. Alloy anodes like tin, antimony, and phosphorus offer very high capacity but expand during use, so nanostructures and composites are being used to improve durability.

3. Solid-State Electrolytes

New materials, such as Na-β-alumina and polymer-ceramic composites, bring safer and higher-energy SIBs. Virginia Tech recently achieved 4.62 mS/cm conductivity with a new glass electrolyte.

4. Global R&D Efforts

The U.S. DOE's $50M LENS Consortium aims to match LFP lithium battery performance without critical minerals. Tesla and Dalhousie University are working on layered oxide cathodes and hard carbon anodes to boost SIB energy density for EVs.

5. Future Outlook

By 2030, SIBs could match LFP lithium-ion costs, making them competitive for grid storage, budget EVs, and electronics. Advances are already underway, with CATL's second-generation sodium-ion batteries now reaching 200 Wh/kg. Beyond that, if they surpass 200–250 Wh/kg, they could expand into mainstream EVs and even aerospace.

Practical Alternative to Sodium-Ion Batteries For Today

While sodium-ion batteries hold great potential for future large-scale storage, they aren't yet ready for portable power. For off-grid, outdoor, and emergency use today, BLUETTI's LiFePO₄-powered Elite 100 V2 Power Station is a proven alternative, offering long life, safety, and eco-friendly design. It uses premium LiFePO₄ cells for over 4,000 cycles, lasting up to 10 years with safe and stable performance.

The battery has 1024Wh capacity and charges up to 80% in 45 minutes with 1,200W AC TurboBoost. At the same time, car charging is 6x faster than standard (1.8 hours with 560W Max). Moreover, the battery also supports 1,000W solar input for a full charge in 70 minutes. With 1200W dual AC and solar input, it can power up the unit up to 80% in 45 minutes and also supports generator charging. Moreover, the battery operates safely without fire risk, and can bear temperatures from -20°C to 60°C.

Weighing just 25 lbs with a compact 17L design and hidden handle, the Elite 100 V2 is easy to carry for travel, camping, or emergencies. It has a 1,800W output (2,700W peak) and 11 ports. The unit can provide power to 90% of appliances, including smartphones, laptops, WiFi, LED lights, and more, over an extended period. At low loads, the unit is totally silent at only 30dB and transitions to the battery in 10ms to keep sensitive devices powered up.

FAQs

1. Are sodium batteries available now?

They aren't widely sold yet and are mainly just prototypes for grid storage. But companies like CATL and Natron Energy are working to start large-scale production in 2024–2025.

2. Why isn't graphite used in SIB anodes?

Graphite does not bind with sodium ions well, thus sodium-ion batteries use hard carbon anodes made of materials such as tin phosphorus.

3. Can SIBs replace lithium batteries in EVs?

Not yet, as their smaller energy storage means they can't go very far. However, they could become applicable in low-cost or short-range electric cars, in the period between 2025 and 2030.

4. Are sodium batteries environmentally conscious?

Yes, as they don't use cobalt or nickel, and instead use materials that are easy to find. It's also easier to recycle them compared to lithium-ion batteries.

Conclusion

If you were wondering before, “How does a sodium-ion battery work?” we've answered in detail in the above guide. In the future, sodium-ion batteries may emerge as a complementary alternative to lithium-ion batteries, particularly in grid storage and low-cost EVs. As the capacity of energy storage and implementations of EVs increase, they are recognized because of their lower cost, increased safety, and environmental friendliness. At the time of this writing, SIBs are less energy-dense than lithium-ion ones but do better when used in cold environments, and are sustainable.

They remain, nevertheless, still in the developmental stage and are not yet ready to meet portable, high-power requirements. So, as for now, lithium-ion batteries remain the best alternative for portable power stations. A great example of a lithium battery-powered station is the BLUETTI Elite 100 V2, which features a 1024Wh capacity battery with 4,000+ cycles. It guarantees up to 10 years of life, can be charged with a wall outlet, a car charger, solar, a generator, or dual AC+ solar inputs. The Elite 100 V2 unit comes in a portable size designed to take it with you when you travel, camp, have an emergency, or live off the grid.