Tesla has published a patent outlining a breakthrough in dry-cathode manufacturing for its 4680 battery cells, potentially slashing production costs. The innovation addresses long-standing challenges in scaling up the process for vehicles like the Cybertruck and Model Y. Published on November 27, 2025, the patent promises to transition from hybrid to fully dry-electrode production.
Tesla's Battery Day in September 2020 introduced the 4680 cells as a revolutionary step in battery production, aiming to apply a first-principles approach to reduce costs. Five years later, the company has faced hurdles, particularly with the dry-cathode process, which has cracked during large-scale manufacturing, limiting throughput.
The new patent, US 2025/0364562, published on November 27, 2025, details a solution to enable a fully dry-electrode process for these cylindrical batteries. Currently, Gen 1 4680 cells used in the Cybertruck and Model Y feature a dry-coated anode but rely on a traditional wet-slurry cathode, requiring toxic solvents, large drying ovens, and waste treatment.
The patent's key innovation is a composite binder using polytetrafluoroethylene (PTFE) combined with stable materials like polyvinylidene fluoride (PVDF), PVDF co-polymers, or poly(ethylene oxide) (PEO). Pure PTFE, valued for its fibrillation properties that bond powders into films, suffers from electrochemical instability, causing high irreversible capacity loss (ICL) of about 127 mAh/g—nearly five times the industry benchmark of 20 to 35 mAh/g for wet-slurry anodes.
By mixing PTFE with higher-stability polymers, the composite creates a protective barrier, reducing ICL to 30 mAh/g with polyethylene or 50 mAh/g with PTFE-PVDF, approaching commercial viability. This addresses PTFE's low lowest unoccupied molecular orbital (LUMO), which leads to defluorination and lithium waste at low voltages.
Manufacturing benefits include faster calendering: the composite forms a cohesive film in three passes versus ten for pure PTFE, tripling speed for high-volume production. A high-shear jet-milling process fibrillizes the binder into a spiderweb-like microstructure, preventing cracking and dusting during winding, thus lowering scrap rates.
Joe from the Cybertruck Owners Club forum summarized: "This patent outlines the 'Gen 2' dry-cathode fabrication process that finally eliminates these steps." If implemented, this could significantly cut costs for Cybertruck and Model Y batteries, making electric vehicles more affordable.