Thick electrodes and solvent-free electrode manufacturing process are likely the next big step in battery tech.

On Wednesday June 27, 2019 we published an article (ref) on a Kyocera/24M manufacturing process. That process sounded very similar to the Maxwell/Tesla manufacturing process using a solvent-free electrode manufacturing process and thick electrodes:

From the Kyocera/24M article:

The use of thick electrodes significantly reduces inactive materials content – copper, aluminum and separator – yielding substantial cost savings.

Moreover, using electrolyte as the processing solvent results in the elimination of numerous capital- and energy-intensive steps like drying, solvent recovery, calendaring and electrolyte filling. The elimination of these steps, and the reduction in plant footprint associated with the steps, yields a capital reduction of up to 50%. In conjunction with the thick-electrode-driven structural bill of materials advantage, the reduced capital cost structure contributes to industry-leading cost of goods.

In two previous articles, we discussed Maxwell’s new solvent-free (dry) electrode manufacturing process (ref1 and ref 2). We pointed out that it is all about the manufacturing process and doesn’t necessarily involve some fancy new electrode chemistry. Maxwell’s process can be used for both NMC and NCA current chemistry electrodes.

The beauty of the process is that it allows a much higher battery line production rate because we eliminate the time-consuming process of driving off the solvent. Capital equipment costs are lower as well since the conventional solvent drying equipment is expensive and takes up a large percentage of the factory floor.

It also appears that both Maxwell/Tesla and Kyocera/24M batteries use a thick electrode in addition to the new dry manufacturing process. Thick electrodes increase energy density. Best we can determine they are not that prevalent in current day batteries because they slow down the manufacturing process considerably due to the excess drying time required to drive off the solvent. Our research indicates drying time around 100 minutes for today’s conventional solvent-based manufacturing process.

The other reason we probably don’t see thick electrodes in many of today’s batteries is that thick electrodes also have lower C rates (power). Tesla would presumably deal with the lower C rate by either increasing the battery size (kwh’s) or perhaps incorporating Maxwell’s capacitor technology. Also it should be pointed out that both the Tesla semi AND Tesla power packs run at low C rates anyway (ref) so Maxwell’s battery would be especially good for those applications.

Here's the evidence that indicates that thicker electrodes and dry manufacturing tech may be the next big step in battery tech:

- Paper presented at the 47th power sources conference, 2016 touting their thick electrode coating wherein Maxwell touted their thick electrodes and dry manufacturing process.

  • Dry Electrode Coating Technology Hieu Duong, Joon Shin & Yudi Yudi, Maxwell Technologies, Inc.

“Maxwell’s DBE offers significantly high loading and produces a thick electrode that allows for high energy density cells”

- Paper presented in 2011 where Maxwell was promoting thick electrodes and dry electrode manufacturing process with A123 battery company:

  • “Dry process Electrode Fabrication” Michael Wixom, May 14, 2012, Project ID:ES134

Produce at least 250m of free standing dry process cathode at thickness >200 μm thickness

- InsideEVs article: Kyocera To Validate 24M SemiSolid Manufacturing Process (ref)

"The 24M SemiSolid manufacturing platform delivers a significant structural bill of materials advantage and requires substantially less upfront capital. Using electrolyte as the processing solvent in a binderless system, the SemiSolid platform allows for production of electrodes 4-5 times thicker than a conventional process. The use of thick electrodes significantly reduces inactive materials content – copper, aluminum and separator – yielding substantial cost savings.