The production of lithium-ion cells for electric vehicles (EVs) is one of the great manufacturing challenges of our age. The challenge is great because of its industrial importance: automotive applications require a hundred times more cell capacity than established electronics markets. The battery is typically 30-40% of the cost of an EV and 80% of this cost is the cells. For EVs to gain greater market share it’s essential they become more affordable.
Realising those cost savings is difficult, not least because of the complexity of the cells as a device and the number of different technology areas involved in their production, including electrochemistry, mechanical engineering, and production engineering, with important upstream contributions from chemistry and materials science.
The process starts with the electrodes, requiring the dosing and mixing of component materials, coating and drying, and densification and slitting. Electrodes then need to be wound with separators, then fixed and inserted into cell cases. Finally, they’re filled with electrolyte and then prepared for use in their first charge and discharge cycles
Improvements for every step are in development: one with huge potential within electrode manufacturing itself is the way in which the active materials are applied to the metal foils which act as current collector and support. The established process, known as wet coating, is proven and near-universally-used, but inherently wasteful. The materials that make up an electrode – active materials, binders, and conductive additives – are mixed in a solvent and coated onto metal foils. The coated foils are then dried at high temperatures, typically 300ºC, which requires 100-metre-long ovens that draw up to 5MW of power. Electrode coating consumes 30% of a cell production plant’s energy, and the ovens take up 15% of the floorspace.
The industry is moving to solvent-free dry coating, which obviates the drying step and therefore the ovens, cutting electrode coating line footprint by 80% and energy consumption by 85%. But the dry mixing stage of the process presents significant technical challenges that prevent it from being adopted at scale: it requires a lot of energy, and the heat and friction generated can significantly alter the properties of the active material, binders, and additives. It’s also hard to achieve a fully homogeneous mixture. Poor mixtures are hard to form into electrodes, impacting yield, and when electrodes can be made, performance and lifetime is not as good as with existing processes.
At Anaphite, we have a breakthrough technology platform that unlocks dry coating's full potential. Instead of mechanical mixing of the electrode components, we use chemistry to combine the materials to produce a well-structured, homogenous composite. This process requires no more energy than dry mixing and produces a dry powder ready for application to the foil. As well as the inherent energy consumption reduction, our process exhibits better and more consistent adhesion than existing dry coating processes, resulting in better cell performance and greater yields.
If used for both anode and cathode production, our technology could enable up to 2% cost reduction at whole vehicle level. It’s applicable to all cell chemistries, can be tailored to each OEM’s compositional and functional specifications, and offers the flexibility for retrofitting into existing gigafactories – with its efficiencies offering a payback period as little as 12 months. If integrated into new plants, they can be smaller and less costly to build, and their reduced power requirements offer greater freedom over location as demand on local grids is less.
Cell manufacturers have long since optimised wet coating but continue to find incremental improvements. Their reluctance to switch to dry coating is understandable, given that the introduction of any new process brings an element of risk, a large amount of capital expenditure, and takes time to ramp up to full production rates. But the pressure from their OEM customers to do it cannot be overstated, given the need to make EVs more affordable and compete with the growing number of Chinese brands.
As the European Policy Centre has stated, in a sector as advanced as battery manufacturing it’s extremely hard to play catch up: “The fact that the EU is not able to compete effectively within the current status quo points to the need to leapfrog into new areas.” Dry coating is one innovation that will enable Europe’s automotive industry to do exactly that.
Joe Stevenson is CEO at Anaphite
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