Donut Lab's Manufacturing Is Different - CleanTechnica

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June 4, 20266 seconds

Christopher Arcus

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Donut Lab’s latest video reveals a novel manufacturing method. Speculation has swirled around the methods and sources of Donut Lab’s batteries since their introduction. We now have word from them supporting some of the sleuthing that has revealed a different manufacturing method — but first, we need to take a look at what standard battery manufacturing is like today.

Lithium-Ion Manufacturing Process

Modern lithium-ion battery manufacturing processes grew from Sony’s first lithium-cobalt batteries intended for mobile electronics. Sony had a background in magnetic tape manufacturing, a process that used acetate tape and coated magnetic particles on it using binders. This process involved assembly lines that used fine magnetic powders, often in slurries, combined with binders that stuck the powders to the tape. The tape coating thickness is controlled by blades that thin the slurry, wiping it down to a thin coating. Then the sheets are cut into strips. Sony adapted its manufacturing technology to lithium-ion batteries by using similar equipment to apply a slurry of metal oxides to metal film to construct a cathode. They used the same technique to coat an anode with graphite. Metal oxide cathodes are sensitive to water. In the assembly line, powder is mixed in slurries use volatile and toxic solvents in a gigantic sealed manufacturing room. The solvent is constantly filtered, removed, and recycled to keep emissions down.

A cathode sheet, separator, and anode sheet are layered, and then packaged in various forms — cylindrical, pouch, or prismatic. Cylindrical packaging winds the layers in a spiral, pouch stacks them, and prismatic combines both methods, folding layers like a newspaper. The entire manufacturing process must be protected from moisture, and at the same time prevent solvents from escaping while maintaining a clean room environment. To remove moisture and solvents, processes are operated under vacuum.

Then the packaged assemblies are injected with liquid organic electrolyte and are subject to a process called formation and aging over a period of weeks. Formation charges the cells and discharges them, changing the internal chemistry and forming an SEI (solid electrolyte interface) layer internally. This process takes time and uses large amounts of electricity and manufacturing space. These steps are the reason lithium battery manufacturing is done at huge scale and at high capital cost and must be near large sources of electrical power. Housing the entire manufacturing line in a sealed chamber to prevent escape of solvents creates high capital cost manufacturing. Lithium-ion battery CAM (cathode active materials) and AAM (anode active materials) are manufactured separately in their own facilities. CAM manufacturing uses calcination (high temperature processing) to create powders. Lithium carbonate is used to make the cathodes and is also used in electrolytes. The entire process is complex, requires moisture-free processing, and relies on global supply chains to produce products. This video shows some of the process steps.

The New Process

Donut Lab’s process is different. It does not rely on low-moisture processing using organic solvents. The entire process can be done in a standard environment, rather than an enclosed, controlled chamber. Manufacturing capital cost is at least an order of magnitude lower than traditional lithium-ion manufacturing. In addition, backend processing does not require filling with electrolyte and formation, another costly, time- and space-consuming process. Elimination of charging during formation also eliminates a large charging energy requirement. The manufacturing equipment can be set up in standard industrial buildings and warehouses or a former grocery store.

Donut Lab’s video did not reveal all the details, but the internet has been buzzing with speculation about CT-Coating AG, a German company that may have links to Donut Lab. This story is interesting, and revealing. It may explain why Donut Lab has been so secretive. CT-Coating’s website shows little information, and further information is only obtainable through NDA. This explains why Donut Lab has been so secretive. If they are a licensee of the process under NDA, they cannot reveal their methods and sources. Just the same, the video fits. The story goes that CT-Coating invented a process using specific materials (nanopaste) to create films on substrates using a process like printing — in this case, something like silk screening or screen printing. Note that various forms of printing are often involved with solid-state batteries. Screen printing uses a mesh to transfer ink to a substrate. A blade or squeegee is used to spread ink onto the screen in one stroke and press the mesh to the substrate on the...