Thermal runaway is a technical term for a rapid uncontrolled increase in temperature. In lithium-ion cells, thermal runaway can be triggered by internal short circuits, physical damage, or overheating of the cell (typically from exposure to temperatures above 60°C). The result of thermal runaway in a lithium-ion cell is typically a fire or explosion.
In most battery packs, the individual cells are small and thermal runaway in a single cell can be hazardous. But the cells in a battery pack are typically in close proximity to one another, and the big danger is if thermal runaway in one cell starts a chain reaction that spreads to the surrounding cells. This phenomenon, referred to as thermal runaway propagation, can lead to serious fires or large explosions.
When thermal runaway occurs in a single cell, the thermal management system must be able to absorb the heat and prevent adjacent cells from getting too hot and subsequently entering thermal runaway as well. AllCell’s PCC™ material was designed in large part to prevent thermal runaway propagation. In the event that a cell enters thermal runaway, the wax in the PCC rapidly absorbs a large amount of heat, while the graphite spreads the remaining heat evenly throughout the entire pack. Simulation results and field tests show AllCell's PCC technology successfully prevents thermal runaway from propagating throughout the battery pack.
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The heat generated from the cell in thermal runaway is absorbed by the PCC. Adjacent cells are not affected.
The heat generated from the cell in thermal runaway quickly spreads to the adjacent cells. The whole battery pack is now a risk for a fire or explosion.