The rise of sodium-ion batteries

As society continues on the path toward full electrification, improving batteries and the search for alternatives to lithium has become crucial for manufacturers and producers looking to make cheaper and better solutions. With limitations and challenges associated with lithium-ion batteries, sodium-ion has emerged as a potential contender as a more sustainable and cost-effective alternative. With tangible benefits already emerging, the interest in sodium-ion only continues to grow, reflecting a shift toward exploring solutions that align with the increasing demand for reliable and eco-friendly energy storage systems.

Sodium-ion batteries 
Sodium-ion batteries are rechargeable batteries that carry the charge using sodium ions in place of lithium ions. During the 1970s and 1980s, interest emerged due to the need for a sustainable and cost-effective alternative to lithium, while today the attraction is based on the need to reduce the reliance on the lithium supply chain, which is stressed due to the dramatic growth in demand for lithium-ion batteries and limited access to key minerals. As sodium-ion batteries have a lower energy density than their lithium-ion counterparts, they are unsuitable for many applications. However, they are especially adept for applications such as short-range vehicles and stationary storage, and as the price of lithium remains volatile, sodium-ion batteries may be a cheaper option.

Benefits of sodium-ion
Offering energy-efficient power with rapid charging capabilities, sodium-ion batteries ensure stability against temperature extremes, protection to prevent overheating or thermal runaway, a longer lifespan, and increased durability over time.

Sodium-based batteries can carry more energy in a smaller package and increasing efforts are being made towards improving their overall efficiency and performance. The battery chemistry also offers an added edge of sustainability, with the abundance of sodium allowing for more diverse sourcing, as well as an overall reduction of critical materials. Additionally, without requiring lithium, copper, nickel, or cobalt, the batteries are less toxic. These batteries aren't just confined to an R&D lab either, with Volkswagen-backed JAC Yiwei rolling out EVs powered by sodium-ion batteries.

Most importantly, they are a cheaper solution than lithium-ion batteries, as the current collectors use aluminum rather than copper. The price differential is so pronounced that the cost of sodium-ion batteries is around $40-80/kWh compared to an average of $120/kWh for a lithium-ion cell.

Rise in Appeal
As sodium is more abundantly available, and with a global push to reduce the use and reliance on lithium, global battery manufacturers and OEMs have begun to utilize this solution. Recently, Sweden’s Northvolt reported making a breakthrough with the technology, and has added sodium-ion to its cell portfolio, 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 the battery manufacturer CATL revealed that its sodium-based batteries would be used in some vehicles this year.

If lithium prices continue to be unpredictable, sodium-ion becomes a stable offering that will keep costs down, unlocking major energy storage while addressing resource-related supply chain concerns occurring across the battery industry.

Improvements
As sodium-ion technology gains momentum, challenges persist. A unique characteristic of sodium-ion batteries is their ability to be manufactured with aluminum current collectors for the anode; however, the small particle size of the hard carbon anode used in sodium-ion batteries makes adhesion a big problem. One way to overcome this hurdle is to modify the design of current collectors, reworking their flat, non-porous structure to one that is three dimensional, textured, and porous to substantially increase adhesion. This can improve mechanical safety and lead to safer and longer-lasting batteries. By using a more 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.

Conclusion
Sodium-ion batteries represent a real stride towards diversifying the available battery chemistries on the global market, in addition to the energy storage mix, offering a sustainable, cost-effective, and promising alternative to lithium-ion technology. Their development and increasing adoption demonstrate a collective effort to address the challenges of energy density, lifespan, and material sustainability, paving the way for sodium-ion batteries that are both economically viable and more environmentally friendly than leading alternatives. As the technology continues to evolve, the potential for sodium-ion batteries to upend the EV and energy sector grows, bringing home the importance of continued innovation and investment in this burgeoning field.