3D printing the next generation of batteries.
The density problem
Last week, some interesting news came out of Carnegie Mellon University about a development in the 3D printing of battery electrodes which immediately raised eyebrows across PTR. Although we do not cover the 3D printing market directly at our company, we’ve been asking various suppliers over the years while attending conferences about their trials and tribulations regarding the technology. From those past interactions, one of the main concerns had centered around density of the end product. In various types of 3D printing methods, the end products produced were porous in nature, thus requiring stronger input materials (like substituting a titanium alloy instead of steal for an automotive or aerospace application) in production which largely offset any gains from manufacturing step process reduction. Of course there are other issues at play such as the overall design of the sub-system not being accounted for when substituting a single component but the density problem may not be such a bad thing after all.
A solution looking for a problem
Capacity, more specifically, energy density is the leading driver of battery developments over the past few years. Most solutions; however, prove just beyond the reach of this production cycle (>5 years) with concepts like solid lithium anodes unable to conquer a dendrite problem and solid electrolytes not gelling ‘pun intended’. Going back to the fundamentals, a battery’s capacity is related to the total amount of active material that participates in the electrochemical reaction. So if the amount of active material can increase without changing the overall volume, this is ideal. Enter the 3D printer.
What had raised eyebrows at PTR was the simple connection of something which naturally produces a high volume, low density product (3D printers) with something which would benefit significantly from those same things. It’s not to say 3D printing and batteries have not had relations, until now, 3D printed battery electrode efforts were limited to extrusion-based printing, where a wire of material is extruded from a nozzle, creating continuous structures. The problem was the focus of the these efforts have not played to the strengths of the production method.
Kicking the tires on the theory
With that promising premise, PTR set out to understand what exactly the solution was proposed by the folks at Carnegie Mellon and their partner, Missouri University of Science and Technology. We set out to find the specific 3D printing technology they used, how common it is as a production method, and what competing, alternative, or complimentary technologies could be doing to accelerate or inhibit its adoption high volume production of electrodes.
How are electrodes currently produced?
Before going into this new method, I feel it’s important to lay out how electrodes are currently manufactured. From analyzing a few capital equipment suppliers, it typically takes four to six steps to produce a battery electrode including process steps to: mix, sinter, coat, compress, and dry. By adopting 3D printing, companies could stand to combine the sintering, coating, and compressing steps.
Which 3D printing technology is being used?
The technology demonstrated in the article utilizes an Aerosol Jet-type of 3D printing with a unique method. The company which provided their technology, Optomec, is one of the only ones utilizing this technology. This raised a flag to PTR knowing that under a scaled environment, a minimum of three equipment vendors would be required for customers to be comfortable with a switch.
As such, one of the key assumptions made from the researchers, a claim of 2-3 years until industrial applications start to show up, comes into question. Until a few more, larger companies, decide to invest in Aerosol Jet printing technology, the electrode application will be unlikely to benefit. Adoption will only occur once the current supply glut is resolved, not occurring until after 2022, according to PTR’s EV Impact Report published last March.
That being said, PTR expects some niche applications for this technology to have earlier uptake, particularly in lower power such as medical devices followed by wearables. This is primarily due to the key value propositions having a high worth as weight plays a critical role.
Link to news article: here