Thermal Runaway Detection System

A system and method for early detection of thermal runaway and electrochemical degradation in battery cells and packs includes a sensor with at least two conductive electrodes separated by a sub-millimeter gap and biased by a controlled voltage. When thermal runaway byproducts enter the gap, current between the electrodes is altered to produce a measurable signal, conditioned by onboard or remote circuitry through amplification/filtering to generate a processed signal. This signal is transmitted to a battery control system to initiate protective actions (e.g., shutdown, cooling activation, or cell isolation). The sensor may be implemented on a printed circuit board or as discrete electrodes and may include a gas-permeable filter that admits vapors and fine aerosols while blocking liquids and debris. The disclosed system enables real-time, sub-second detection of early thermal runaway precursors before temperature rise or combustion occurs, enhancing safety and reliability of lithium-ion and other electrochemical energy storage systems.