Li-ion, Na-ion Comparisons in the Real World

I have written a lot about different battery chemistries in this column over the last few years. There are a huge number of researchers around the world working on either new battery chemistries, or trying to improve the ones we currently use. It’s a slow process, and those advancements could take years, or even decades before they reach the market. Li-ion batteries have been the battery of choice for the majority of applications that we use today. It’s not that they are ideal batteries in themselves, and anyway, everything can be improved. It is more that they are a jack of all trades, having decent specifications across the board and we have struggled to find an alternative that can displace them, even in a single application area.

One of the few competing battery types that has actually made it to market so far is sodium-ion (Na-ion) chemistry. Although Na-ion batteries will never compete directly with lithium-ion batteries on power density in uses such as full-size EVs or consumer electronics, they do have some advantages that make them attractive for applications such as renewable energy storage and compact vehicles. These advantages include longevity (around 6 times more charge/discharge cycles than Li-ion), lower cost, safety, wide availability of materials and better operation in temperature extremes.

What we haven’t generally seen yet before now, is the two battery chemistries compete head-to-head in real-world applications. However, that has now changed as Yiwei and JMEV, two Chinese manufacturers, have launched small Na-ion powered vehicles. The JMEV EV3 is especially of interest as the company makes both Li-ion and a Na-ion variants of the vehicle. The lithium battery beats the sodium by 50km, with respective ranges of 301 km to 251 km. These cars are intended for city use, rather than longer excursions, so the range difference is not as important as it may first appear. The Na-ion vehicle is cheaper as expected, but only by around $500 – RMB 62,800 ($8687.95) to RMB 58,800 ($8134.58), and safety and cold weather performance are additional benefits for the Na-ion vehicle. In that example, the Na-ion battery seems quite competitive.

In a second example, Peter Holderith has also compared the two chemistries on the Motor1 website. Peter had already built a souped-up Honda Motocompacto electric scooter (a separate blog on the site that is also worth reading), and decided to compare off-the-shelf Li-ion and Na-ion batteries. He bought the batteries in 18650 format and built battery packs to hold them. His conclusion was that the sodium batteries were perfectly capable of powering the base-model scooter to its original specification, but Li-ion ones would be needed for the ‘enhanced’ version of the scooter. In summary, he found that “the lithium pack contains 108Wh of energy and can provide 864 W continuously at nominal voltage. The sodium pack contains 46.8Wh and can put out 468 W of energy, but is much cheaper, costing between 25% and 33% of the lithium battery price”.

It is important to remember that Li-ion technology is already mature, but Na-ion batteries are at the beginning of their development and should have more room for improvements.

https://www.motor1.com/features/713344/sodium-ion-motocompacto-type-r