As the world continues on its electrification trajectory, improving batteries and the quest for alternatives to lithium has become a focal point in the ever-evolving landscape. While the limitations and challenges associated with lithium-ion batteries have spurred a search for sustainable and cost-effective alternatives, sodium-ion has emerged as a potential contender. From its promising technology to its benefits, the interest in sodium-ion only continues to grow, reflecting a global shift towards exploring diverse and innovative solutions that align with the increasing demand for reliable and eco-friendly energy storage systems.
About Sodium-Ion Batteries
Sodium-ion batteries are a type of rechargeable battery that work like lithium batteries. However, rather than carrying the charge using lithium ions, they do so with sodium ions.
During the 1970s and 1980s, interest in the technology emerged due to the need for sustainable and cost-effective alternatives to lithium-ion batteries. Today, the interest in sodium-ion batteries mainly revolves around reducing the reliance on the lithium supply chain, which is under stress due to the dramatic growth in lithium-ion battery consumption. As sodium-ion batteries have a lower energy density than their lithium-ion counterparts, they are unsuitable for many applications. However, they could be appropriate for short-range vehicles and stationary storage. Additionally, if the price of lithium were to spike again in the future, sodium-ion batteries could work out cheaper, although the entire sodium supply chain would have to scale up to ensure its promise for cost competition. As a result, it is thought that by 2030, sodium-ion batteries could make up for 23% of the stationary storage market.
The Technology
In sodium-ion batteries, the ion carriers are sodium ions (Na⁺). These ions move between the anode and cathode via the electrolyte during the process of charging and discharging. While charging, the anode goes through sodiation, where sodium ions are inserted into the anode material. While discharging, the cathode undergoes desodiation, where sodium ions are extracted from the cathode material.
While sodium-ion has a voltage window between 2.7V-3.8V, lithium-ion’s is between 3.2V-4.3V. This can vary depending on the materials that are chosen for the anode and cathode components. Recent sodium-based batteries have been carrying more energy in a smaller package and an increasing amount of efforts are being made towards improving their efficiency and performance.
Benefits of Sodium-Ion
Offering energy-efficient power with rapid charging capabilities, sodium-ion batteries ensure stability against temperature extremes, safety to prevent overheating or thermal runaway, a longer lifespan, and increased durability over time. Moreover, they are a cheaper solution to traditional lithium-ion batteries, as the current collectors use aluminum rather than copper. Indeed, the cost of sodium-ion batteries is around $40-80/kWh compared to an average of $120/kWh for a lithium-ion cell. As a result, JAC Group’s Yiwei, backed by Volkswagen, introduced the first sodium-ion battery-powered EV at the end of 2023, with deliveries expected in January 2024.
In terms of sustainability, the abundance of sodium allows for more diverse sourcing as well as a reduction in the need for critical materials. Furthermore, by not needing Lithium, Copper, Nickel or Cobalt, this also makes them less toxic than other batteries.
Room for Improvement
Though sodium-ion batteries are approaching the capabilities of their entry-level lithium-ion counterparts, they grapple with low energy density. Therefore, in comparison to LFP and NMC, sodium-ion batteries require a larger number of cells to achieve the same energy storage capacity. Indeed, despite recent strides, these batteries still fall short in terms of energy density, with current figures hovering around 160/kWh compared to the aimed-for 200/kWh. Consequently, sodium-ion is more difficult to use in certain applications, but could be better suited for short-range vehicles and stationary storage. Additionally, their lifespan is shorter by approximately 2,500 cycles, making them less appealing for long-term and high-performance applications.
Why the Sudden Rise in Interest?
In an attempt to reduce the use of lithium, attention is shifting towards alternative solutions including sodium. As this mineral is more abundant, sustainable and cheaper than lithium, battery manufacturers and OEMs are looking to adopt it. Indeed, Sweden’s Northvolt reported making a breakthrough with the technology, and has added sodium-ion to its cell portfolio, thus enabling the expansion of cost-efficient and sustainable energy storage systems worldwide. Similarly, Chinese EV maker, BYD, signed a deal to build a $1.4 billion sodium-ion battery facility while battery manufacturer, CATL, revealed in April that its sodium-based batteries would be used in some vehicles this year.
The success of sodium-ion batteries could mitigate the demand for lithium, offering a promising alternative in the energy storage landscape. Should lithium prices experience another surge in the future, sodium-ion batteries might emerge as a cost-effective option, provided that the entire sodium supply chain scales up to fulfill its potential for competitive pricing. These cost advantages highlight the importance of their successful development and widespread adoption in addressing both economic and resource-related concerns in the battery industry.
Improving Sodium-Ion with Addionics
As sodium-ion technology gains momentum as a promising alternative to lithium, challenges still persist. Indeed, one particular characteristic of sodium-ion batteries is that they can use aluminum current collectors for the anode. However the small particle size of the hard carbon anode used in sodium-ion batteries makes adhesion a bigger problem. Addionics’ 3D Current Collectors can potentially provide a solution due to their superior adhesion properties. This betters mechanical safety and leads to safer and longer-lasting batteries. By using a porous structure, the active material can seep into the pores and the graphite sticks to the material more efficiently rather than peeling off like it does with a traditional dense foil. Therefore, using Addionics’ 3D Current Collectors can improve sodium-ion batteries, allowing them to reach their potential faster.
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