Tesla has revealed a groundbreaking redesign of its 4680 battery cell, replacing conventional tabs with a continuous metal foil hem to streamline manufacturing and enhance performance. The patent, published on July 14, 2026, targets the battery's current collection system—a longstanding challenge in cylindrical lithium-ion cells.
Reinventing Battery Architecture
Cylindrical lithium-ion batteries, including Tesla's 4680 and Panasonic's 2170 cells, traditionally rely on a "jelly roll" structure, where anode, cathode, and separator layers are wound into a spiral. In standard designs, current is collected through tabs—small metal strips welded to the electrode edges. However, this approach forces electrons to travel long distances along the metal foil, increasing internal resistance and generating localized heat, particularly during fast charging or high-power discharge.
Tesla's new patent eliminates tabs entirely. Instead, the company proposes folding the uncoated edges of the metal foil inward to create a continuous hem. After winding, these hem layers naturally align and form a seamless current collector along the entire electrode edge. The design removes the need for laser cutting, tab welding, and debris management—steps that add complexity, cost, and potential failure points to battery production.
Manufacturing Efficiency and Safety Gains
The hem-based design simplifies the production process by removing multiple stages, including tab fabrication, cutting, slotting, and waste handling. According to Tesla's patent, this reduction in manufacturing steps lowers equipment complexity, energy consumption, and labor requirements while minimizing material waste. The company also claims the streamlined structure improves precision and accelerates electrolyte filling, a critical step in battery assembly.
Beyond cost savings, the new design may enhance safety. The hem structure shortens electron pathways, reducing internal resistance and heat buildup. Additionally, the simplified architecture creates larger internal channels for gas release during thermal runaway, a key factor in preventing battery fires. These improvements could make the 4680 battery more resilient under extreme conditions, such as fast charging or high-performance driving.