Scientists at the Tokyo University of Science say the sodium-ion battery can achieve 1,600 Wh/kg.

Last June, we told you about how Na-ion batteries could be near with the help of macrocyclic molecules. What that experiment did not overcome was the low energy density of the sodium-ion battery. Researchers from the Tokyo University of Science may have solved this with a new hard-carbon anode that can make Na-ion batteries deliver 1,600 Wh/kg. That’s 19 percent more than Li-ion cells, which typically deliver 1,430 Wh/kg.

If you ask why this is great news, bear in mind that sodium is way more abundant and cheaper than lithium. If anyone is able to put together a working and commercially viable Na-ion cell, that could make electric cars immediately more affordable than combustion-engined vehicles.

This is what professor Shinichi Komaba explains in the video above, shot in 2014. Although it may seem an old video, it shows for how long Komaba and his team are dedicated to bringing a sodium-ion battery to market. And they are not the only ones trying to do that, as Peter Allen explains in the video below.

As you can see, professor John Goodenough is also trying to create a viable Na-ion cell. For the lithium-ion batteries' creator to be involved in these efforts is proof of how promising they are.

What Komaba and his team managed to do was to develop a new hard-carbon anode that requires lower temperatures in its heat treatment: 1,500ºC instead of 1,900ºC. Another secret of this special hard carbon is using MgO (magnesium oxide). It allows the anode to have 478 mAh/g. According to the researchers, it is the highest capacity ever achieved for this type of material. It is this anode that allows their sodium-ion cells to be more energy-dense than lithium-ion batteries.

If you think sodium-ion batteries need to be heated to work – such as sodium/nickel chloride cells used back in the 2000s, it doesn’t. It works like regular Li-ion batteries and is considered much safer.

What didn’t help was the low energy density of previous prototypes and dendrites' formation, as Allen explains in the video above. We got in touch with Komaba to try to learn how they have solved the dendrite issue.

It is interesting to know that the Tokyo University of Science researchers are also trying to create a potassium-ion cell, as the video below let us know.

Whatever the alternative to lithium is, it will be good news. The world needs batteries, either in cars or for stationary purposes. The more affordable they are, the safer the environment will be. 

Source: Tokyo University of Science