Honda’s Solid-State Battery breakthrough explained

Honda, the Japanese automaker, recently made an announcement which shocked the automotive world. This announcement stated that the company will now ‘begin producing solid-state EV batteries’ and this will commence in January 2025.

Before this, even though there has been years of research being conducted, there is not a company that has been able to create a production line and then add a solid-state battery into a test car. However, if Honda is able to complete their groundbreaking announcement, this event will be one of the largest steps forward in the history of EVs.

The announcement that was made, spoke about Honda being able to have a factory ready and operational within a few weeks. Officially, Honda called this facility, “a demonstration line.” The plan is for it to be located in Sakura City, Tochigi Prefecture and for it to cover 27,400 m² (295,000 ft²). To help this project along, Japan’s Green Innovation Fund agreed to supply the project with some funding.

So far, Honda has already added equipment and tooling to the project, as the building were completed in Spring 2024 and although the facility isn’t quite complete, the company has almost finished installing all the manufacturing equipment. Being in this position places Honda ahead of a lot of other businesses, especially as producing solid-state batteries is now a process that the company could actually be completing very soon.

In the past, multiple companies have attempted similar projects and many of them spoke about factories being under construction or have even produced working protypes. However, it is only Honda that has been able to get this far.

This kind of progress occurred once Honda had one of their biggest breakthroughs in solid state batteries, which was its roll-pressing technique. Doing this means that the SSB cells are stamped together whilst they are in assembly. This increases the density of solid electrolyte layers, therefore improving energy efficiency and simultaneously solving two of the largest problems that have come along with preventing car-sized SSBs from hitting the road. Its clear that most kinds of batteries store their energy in a liquid or as a paste, which proceeds to naturally conform to whatever space it’s in, whilst also making the near-perfect contact with the electrodes that allow electricity to flow. On the other hand, solid-state batteries store their energy within a solid electrolyte, which is most commonly in the form of a powder. Consequently this means that solid-state electrolytes are full of tiny air gaps, which prevents electricity travelling through it, because electricity can’t travel through air, unless it is arcing, which is not recommended within batteries. So, pushing the batteries together, means that the air and empty spaces is squashed out, resulting in the solid electrolyte making perfect contact with the battery’s electrodes. Furthermore, pressing the batteries together, has the beneficial effect of speeding up the production rate.

Now that Honda has achieved this, they have said that they are also looking to simplify the batteries’ cooling structures. This is because in comparison to lithium-ion batteries, ASSBs are fairly heat resistant, meaning that heat doesn’t damage them very easily. Therefore, whilst they still need to be kept cool, Honda is looking to use a much simpler cooling process, which will be beneficial to the production cost, production time and later on within the battery recycling industry too.

On top of all of this, Honda has even managed to find a way to prevent the dendrites issue that is often found in solid-state batteries. Dendrites are small, spiky lithium crystals which occur when the lithium separates out of the various compounds located inside the battery. These causes issues, as when they grow, they pierce the battery’s internal structures and then proceed to destroy it from inside. The solution that prevents this issue, which was created by Honda, is incredibly simple, it is just adding a layer of plastic, thin enough to allow electricity to flow through, in the place where the dendrites would usually grow.

This new battery and battery production system is a groundbreaking solution on multiple counts and whilst it is not expected that this thin polymer to prevent dendrites will last forever, it will add years to the battery’s life. Plus, now that this has been achieved, Honda is already expanding their practise to look into creating solid-state batteries which are suitable for use on both land and air. So far, the future plan is for them to create batteries which are suitable for cars, trucks, motorcycles and finally, aircrafts.