A Cryogenic Planetary Ball Mill (also known as a Cryo-Mill) is a specialized tool used to process materials that are either heat-sensitive, prone to oxidation, or too "rubbery" to grind at room temperature.

In a high-speed planetary mill, the friction between the balls and the jar can easily push internal temperatures above 100°C. For certain battery components, this is destructive: (1) Polymer Electrolytes & Binders: Materials like PEO or specialized ionomers become "gummy" when heated. At cryogenic temperatures (below -100°C), they reach their "glass transition temperature" (Tg) and become brittle, allowing them to be pulverized into fine powders forDry Battery Electrode (DBE) process. (2) Preventing Thermal Degradation: High-energy milling can cause "phase transitions" in active materials. Cryo-milling preserves the original crystalline structure of sensitive cathodes or Solid Oxide precursors. (3) Controlling Reactivity: For high-surface-area materials like nano-silicon, the cold environment slows down oxidation during the milling process.

References:

Q. Yan, et al., Cryogenic Milling Method to Fabricate Nanostructured Anodes, ACS Appl. Energy Mater. 2020, 3, 11, 11285–11292. 

J. Liu, et al., Efficient liberation of electrode materials in spent lithium-ion batteries using a cryogenic ball mill, Journal of Environmental Chemical Engineering, 2021, 9, 106017.