What is Sodium ion Battery Cell? LiFePO4 Alternative?

In the evolving landscape of energy storage, sodium ion batteries have emerged as a significant player. As an alternative to LiFePO4 batteries, they offer unique benefits and potential applications. In this article, we’ll delve into what sodium ion batteries are, their characteristics, and why they might be the future of battery technology.

What are sodium-ion batteries?

Sodium ion batteries function similarly to traditional lithium-ion batteries but use sodium ions as their primary charge carriers. This switch to sodium offers a more abundant and cost-effective solution compared to lithium-based systems.

Common Sodium Ion Battery Shapes

Sodium ion batteries come in various shapes, including cylindrical, prismatic, and pouch cells, each with unique advantages for different applications.

Sodium Ion Battery Charging and Discharging Principle

These batteries operate on the principle of moving sodium ions between the cathode and anode during charging and discharging, a process that is efficient and offers high energy density.

Sodium Ion Battery Pros and Cons

Pros:

Abundant and Equitably Distributed Resources

One of the significant advantages of sodium batteries lies in the abundance and equitable distribution of their raw materials. Sodium, with a crustal abundance of 2.3%, is far more plentiful than lithium at 0.0017%. This abundance suggests that sodium batteries have greater potential in terms of raw material supply, especially as the global electrification accelerates and the shortage of lithium resources becomes more pronounced. Unlike lithium, which is concentrated in South American countries like Argentina, Chile, and Bolivia, sodium is more evenly distributed across the globe. This reduces reliance on specific regions for resources and lowers supply chain risks. Sodium’s widespread presence in the form of salts on land and in the oceans makes it cost-effective and easily accessible. These characteristics position sodium batteries as a sustainable and cost-efficient alternative, contributing to the widespread adoption of battery technology and the advancement of the electric vehicle industry.

Cost-Effective Manufacturing and Materials

Sodium-ion batteries offer a notable cost advantage over lithium-ion batteries, primarily due to the abundance and lower cost of sodium compared to lithium. As members of the same alkali metal group in the periodic table, sodium and lithium share similar physical and chemical properties. However, the increasing demand for lithium-ion batteries has led to a supply shortage and a significant rise in the price of lithium carbonate, a key battery material. In contrast, sodium’s rich presence in the Earth’s crust translates to lower costs and less susceptibility to supply-demand price fluctuations.

The production process of sodium-ion batteries is similar to that of lithium-ion batteries, involving steps such as electrode manufacturing (mixing and drying the electrode paste, coating, etc.) and battery assembly (rolling, cutting, winding/stacking, casing, sealing, formation, and sorting). A key difference is that sodium-ion batteries can use aluminum foil as the negative current collector, allowing for the use of the same aluminum tabs for both electrodes, simplifying welding and related processes. This compatibility means that existing lithium-ion battery assembly lines can be easily adapted for sodium-ion battery production, significantly reducing the cost of transitioning to this technology.

Compared to mainstream power batteries used in electric vehicles, such as lithium iron phosphate and ternary lithium batteries, sodium-ion batteries have been developed as an alternative option. The impetus for this development stems from the persistent high prices of materials like lithium carbonate due to supply-demand imbalances from 2021 to the first half of 2023, a problem that sodium materials have not faced. This cost-effectiveness and adaptability of sodium-ion batteries make them a promising contender in the evolving energy storage market.

Superior Safety Performance

Sodium-ion batteries exhibit significant safety advantages due to their high internal resistance, which results in lower current and less heat generation during short-circuit conditions, reducing the risk of thermal runaway. Compared to lithium-ion batteries, sodium-ion batteries demonstrate greater stability under extreme tests such as overcharging, over-discharging, short-circuiting, and puncture, without igniting or exploding. The higher thermal runaway temperature of sodium-ion batteries, coupled with their passivation and oxidation properties, makes them less prone to spontaneous combustion in high-temperature environments. Additionally, the larger electrochemical window of sodium salt electrolytes lowers the likelihood of electrolyte decomposition during reactions, further enhancing the stability of the battery system. Sodium-ion batteries also allow the use of metallic aluminum as the anode current collector, effectively avoiding the over-discharge issues associated with graphite-based lithium-ion batteries. These characteristics make sodium-ion batteries safer for storage and transportation, especially in high-temperature regions such as India, the Middle East, and Africa, where their safety benefits are particularly compelling and could make them an ideal choice for energy storage solutions in these markets.

Exceptional Low-Temperature Performance

Sodium-ion batteries exhibit outstanding performance in low-temperature conditions due to their high ion conductivity, lower concentration requirements for the electrolyte, and reduced viscosity of the electrolyte at low temperatures compared to lithium-ion batteries. These batteries can operate normally within a temperature range of -40°C to 80°C, with some products maintaining up to 88% capacity at -20°C, significantly outperforming the approximately 60-70% capacity retention of lithium iron phosphate batteries under similar conditions.

In contrast to the -20°C to 60°C operating temperature range of lithium-ion batteries, sodium-ion batteries can function effectively across a broader temperature spectrum, from -40°C to 80°C. Even in extreme low temperatures, such as -70°C to 100°C, sodium-ion batteries can maintain over 90% discharge capacity retention, demonstrating a clear advantage in cold-weather performance.

Superior Rate Performance

Sodium-ion batteries excel in rate performance due to their lower solvation energy compared to lithium ions, stronger interfacial ion diffusion capabilities, and a smaller Stokes radius for sodium ions. This results in higher ionic conductivity in sodium salt electrolytes at the same concentration compared to lithium salt electrolytes, leading to faster charging rates. According to data from CATL, sodium-ion batteries can charge up to 80% in just 15 minutes, while Zhongke Hai钠 has claimed that its batteries can reach 90% charge in 12 minutes. These charging speeds are significantly faster than the typical 30-minute charge to 80% for lithium-ion batteries under normal conditions, highlighting the potential of sodium-ion batteries for fast-charging applications.

Environmental Sustainability

Sodium-ion batteries offer significant environmental sustainability advantages over traditional batteries made from nickel, manganese, cobalt, or iron phosphate. By replacing graphite with hard carbon, these batteries can substantially reduce their carbon footprint, with emissions as low as 10-20 kg of CO2 per kWh, compared to the 100-150 kg of CO2 per kWh associated with current comparable batteries. Researchers at Chalmers University of Technology in Sweden have demonstrated that sodium-ion batteries have an equivalent climate impact to their lithium-ion counterparts, yet they carry no risk of raw material depletion.

Arvidsson, one of the researchers, concluded that “sodium-ion batteries are much better than lithium-ion batteries in terms of impact on mineral resource scarcity and are equivalent in terms of climate impact. Depending on the scenario, they result in between 60 and just over 100 kilograms of carbon dioxide equivalents per kilowatt-hour theoretical electricity storage capacity, which is lower than previously reported for this type of sodium-ion battery. It’s clearly a promising technology.”

Cons

Energy Density Lags Behind Lithium-Ion

Despite sodium-ion batteries’ advantages in cost and sustainability, their relatively low energy density remains a major shortcoming.

Under current technical conditions, the cell energy density of sodium-ion batteries is approximately 70-200Wh/kg, which is higher than lead-acid batteries at 30-50Wh/kg. Compared to ternary lithium batteries at 200-350Wh/kg, sodium-ion batteries are inferior, but there is an overlap with lithium iron phosphate batteries at 150-210Wh/kg. Moreover, sodium-ion batteries still have considerable room for technical improvements.

Sodium ion Cell Parameter

HiNa Battery (中科海钠) 80Ah Sodium-ion Cell (Na-ion) Parameter
Cell Model: NaCP50160118-ME80

HiNa Battery (中科海钠) 240Ah Sodium-ion Cell (Na-ion) Parameter
Cell Model: NaCP73174207-ME240

Final Thoughts

Sodium ion batteries represent a promising direction in battery technology, balancing cost, sustainability, and performance. As research and development continue, they may soon become a mainstream alternative to traditional lithium-ion batteries, including LiFePO4.