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Sodium-ion (Na-ion) batteries use sodium ions instead of lithium ions to store and deliver power. Sodium is much more abundant and environmentally friendly than lithium, but there are still several challenges left to make sodium-ion batteries the new battery champion.

Batteries are becoming crucial to everyday life, and whoever comes up with a better battery has the world on a platter. Sodium-ion batteries are a top contender to the crown held by lithium-ion batteries, but what exactly makes them special?

What Is a Sodium-Ion Battery?

Sodium-ion batteries are batteries that use sodium ions (tiny particles with a positive charge) instead of lithium ions to store and release energy. Sodium-ion batteries started showing commercial viability in the 1990s as a possible alternative to lithium-ion batteries, the kind commonly used in phones and electric cars.

How Sodium-Ion Batteries Work

Sodium-ion batteries, also called Na-ion batteries, use a chemical reaction to store and release electrical energy. Like all batteries, they have two electrodes (a positive electrode and a negative electrode) separated by an electrolyte, which is a special substance that allows ions (tiny particles with a positive or negative charge) to move between the electrodes.

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Sodium-ion batteries work similarly to lithium-ion batteries, but they use sodium ions instead of lithium ions. The choice of materials for the electrodes and electrolytes can affect the performance and lifespan of the battery, so researchers are constantly experimenting with different combinations to find the best combination of cost, performance, and safety. Generally, the cathode (the negative electrode) and electrolyte contain sodium.

What Makes Sodium-Ion Batteries Great?

Lithium-ion batteries rule the roost at the moment, and there's plenty of research to make them even better than they are right now. Still, sodium-ion batteries have a few distinct advantages over them.

  • Sodium is a much more abundant element than lithium, making it easier and cheaper to obtain. This could make sodium-ion batteries less expensive to manufacture than lithium-ion batteries and more environmentally friendly to boot!
  • Sodium-ion batteries have the potential to offer similar energy density as lithium-ion batteries, making them suitable for a wide range of similar applications, although they aren't quite there yet.
  • Sodium-ion batteries are generally considered safer than lithium-ion batteries, as they are less prone to overheating and catching fire. Although several experimental lithium batteries have shown incredible resistance to damage that would make current batteries explode.

The Drawbacks of Sodium-Ion Batteries

There's no such thing as perfect battery technology, and there are a few reasons sodium-ion batteries haven't taken over from lithium yet.

  • Sodium-ion batteries have a lower voltage (2.5V) than lithium-ion batteries (3.7V), which means they may not be suitable for high-power applications that require a lot of energy to be delivered quickly.
  • They have a slower charge/discharge rate than lithium-ion batteries, which may not be suitable for applications that require a lot of power to be delivered quickly (such as electric vehicles).
  • Sodium-ion batteries still have limited charge cycles before the battery begins to degrade, and some lithium-ion battery chemistries (such as LiFeP04) can reach 10,000 cycles before degrading.

Apart from these technical pros and cons, the manufacturing chain for sodium-ion batteries still has some kinks to sort out before it can become a widespread commercial product. Not to mention that engineers and scientists are working on solutions to this battery technology's remaining weak points.

The Present and Future Potential of Sodium-Ion Batteries

Researchers and companies around the world are working to improve the performance and commercial viability of sodium-ion batteries. Some key areas of focus include improving the energy density and voltage of sodium-ion batteries, as well as increasing their lifespan and charge/discharge rate.

If these efforts are successful, sodium-ion batteries could become a viable alternative to lithium-ion batteries in the future. They could potentially be used in various applications, including portable electronics, electric vehicles, and stationary energy storage systems.

Related: How Long Do Electric Car Batteries Actually Last?

In 2022, researchers at the US Department of Energy made a major breakthrough in improving the durability of sodium-ion batteries. By changing some of the chemistry in the battery, the prototype coin-sized batteries lasted in excess of 300 cycles while maintaining more than 90% capacity. However, even without this new approach to chemistry, it seems that sodium-ion batteries are about to hit mass production anyway.

Sodium-Ion Mass Production Has Already Started

In December of 2022 it was reported that a company named HiNa in partnership with Chines state-owned China Three Gorges Corporation, had started mass production of sodium-ion batteries. The first generation of HiNa batteries offer energy density figures of 125Wh/kg, which is around half that of lithium-ion batteries. However, these batteries are rated for around 4500 charge cycles, which is significantly more than typical lithium-ion batteries.

Typical lithium iron phosphate batteries offer energy densities similar to sodium-ion batteries, and the rated number of charge cycles is also similar. That puts sodium-ion batteries in direct competition with these batteries for applications such as backup inverter power or electric vehicles.

The next generation of these HiNa batteries are slated to have a 200Wh/kg energy density, and subsequent generations are expected to exceed that. Considering that some electric cars using lithium batteries have an energy density below 250Wh/kg, these early mass-produced sodium-ion batteries have serious potential to reduce the cost of power storage.

However, just like LiFeP04 batteries, don't expect this technology in your smartphone or laptop any time soon. In these small devices, energy density is still the most important consideration. However, don't be surprised if your electric car or solar power battery system gets a little saltier in the near future.