In addition to a potentially easier and cheaper manufacturing process, I think a key benefit of Maxwell's technology is that the improved properties of their dry coated electrodes allow for new cathode and anode chemistries (with higher energy densities) which do not function adequately with electrodes manufactured using the traditional methods. I would guess the first generation of Maxwell electrodes would use Tesla's current cathode chemistry but a new anode chemistry, but it also sounds like they expect their dry electrodes to open up options for new cathode chemistries including cobalt free according to their ppt. Whether dry coated electrodes also have properties which will make solid state battery designs easier to commercialise i don't know - i don't see any reference to solid state in their materials other than the 2 words on their ppt.
From Maxwell's papers:
- "results suggest that dry coated electrodes exhibit lower particle-to-particle contact resistance and charge transfer impedance, likely due to a uniform network of interconnects between binder and active material particles."
- "The lower charge transfer and contact resistance in the dry coated electrode offer higher energy density cell designs with improved power capability."
- "Maxwell’s dry coated battery electrode offers extraordinary benefits, including manufacturing cost reduction, elimination of solvent toxicity, enabling the application of liquid sensitive battery chemistries and enhancing cell performance, particularly at high loading weights when compared to conventional wet coated electrode in discharge rate studies."
- "In addition to manufacturing flexibility, the cohesion and adhesion properties of electrodes derived from the dry process are superior in the presence of electrolyte at high temperatures compared to those produced using the wet coating technology."
- "Maxwell’s DBE offers significantly high loading and produces a thick electrode that allows for high energy density cells without compromising physical properties and electrochemical performance"
- "As a solvent-free process, the polymer binder is not dissolved; as a result, the binding mechanism is an inter-connecting network comprised of point-contacts with the active material particle surface. This dry binding structure is less obtrusive and, consequently, enables lithium ions better access to the active material particles. This feature is especially advantageous for high rate performance in high energy density electrodes."
- "Various dry coated battery electrodes were fabricated, including NMC811, NCA, LFP, LTO, sulfur/carbon and silicon composite, using Maxwell’s dry coating electrode technology. Maxwell’s dry coating electrode technology can be used to produce advanced high capacity NMC811 cathode and silicon-graphite composite anode that can deliver designed discharge capacity."
From ppt: "Technology Enablement & Environmentally Responsible: No Solvents, Next Gen Materials, Cobalt-Free, Solid State "
It looks like Maxwell has another paper due out shortly with results from their pilot production plant:
Dry Processed Nickel-Rich Layered Transition Metal Oxide Cathode Electrode
- "The benefits are lower CO2 emission, lower capex and opex cost, improved energy density and the ability to process moisture sensitive or reactive materials. "
- "This paper will report the physical properties of nickel-rich layered dry cathode film produced at the lab and pilot production level and their electrochemical performance with coating loading of 30-40mg/cm2 per coating side, which is significantly heavier than a typical wet cast electrode in the range of 20-24mg/cm2per coating side in commercial high energy 18650 cell."
To be more clear, my guess is that
the number one and quickest benefit of Maxwell’s technology is to allow for a thicker cathode layer and hence a higher active materials volume ratio and higher cell energy densities even with existing cathode chemistry.
The cathode energy density is generally the limiting factor in cell energy density so obviously increasing the % of cathode material in a cell is the easiest way to increase cell energy density. In fact I understand this has been the key driver of battery cell improvements over the past 20 years – “The gradual improvement in energy density over the last 20 to 25 years was mostly due to cell engineering, which has increased the volume ratio of active materials from ~20% in early Li-ion cells to ~45% in today’s state-of-art cells [7,8]. Thickening electrodes in cell stacks while making current collectors and separators thinner is one effective approach to continuously increasing the active material content for higher energy density and lowcost Li-ion batteries.”
Understanding limiting factors in thick electrode performance as applied to high energy density Li-ion batteries (Journal Article) | OSTI.GOV
The problem with this simple approach is increasing cathode thickness beyond a certain amount can lead to underutilisation of the cathode materials and also lower power density. So you get diminishing returns and counterproductive effects after a certain thickness.
I think this is why the focus shifted to solid state batteries – lithium metal anodes have a much higher energy density so they allow for much thinner anode and hence a higher % of cathode in the overall cell (solid state can theoretically have other potential benefits like faster charge time, increased cycles, less flammable etc). The solid state electrolyte is mainly just there as requirement to safely manufacture lithium metal anodes.
It looks like Maxwell is increasing cathode thickness c.50% within the current 18650 cell design. So they must be reducing thickness of the electrolyte, anode or separators etc a corresponding amount (anode thickness reduction would require a new anode chemistry with higher energy density). If they manage to fully utilize the full thickness of this cathode material without adverse impact to power density, safety, cycle life etc, they should get a significant increase in cell energy density without changing the cathode chemistry while remaining viable for quick deployment in EVs.
I think Tesla’s battery breakthrough approach may end up looking very much like their Camera vs Lidar approach for Autonomy. Everyone else spends 5 years trying to bring Lidar costs down from $100k to $10k while Tesla gets further just using cameras which were $100 all along. Everyone else spends 5-10 years trying to commercialise new solid state battery designs while Tesla specs beat solid state just from iterating the current technology.
Also, I'm not a battery cell expert, i've only followed the tech for a while and read a bunch of papers, so someone correct me if any of this is wrong.
