This technology places a patterned functional layer made of expanded graphite and a binder between the electrode current collector and the active material layer. When the expanded graphite expands at high temperatures (approx. 140°C or higher), it physically separates the active material layer from the current collector, causing a sharp increase in resistance to prevent thermal runaway during a short circuit.
Conventional secondary batteries are at high risk of fire, as short circuits cause rapid temperature spikes leading to thermal runaway. Methods using flame retardants have limitations in ensuring proactive safety, as they only activate after ignition has already begun.
This technology involves coating a current collector with a patterned layer containing openings, using a mixture of expanded graphite (particle size 500nm–7㎛, 200–600% expansion at 140°C) and a secondary binder like SBR. Upon exposure to high heat, the expanded graphite swells, detaching the active material layer from the current collector and forcing the circuit resistance up to cut off the current. It can be applied to fields prone to major fires from short circuits, such as EV pouch cells, energy storage modules, and power tool batteries, serving as a passive safety device that allows the cell to disconnect its own circuit before ignition occurs.
WO2024-237533A1
