Optical Aerosol Sensing for Electrolyte Leakage Monitoring in Lithium-Ion Batteries: A Method for Early Safety Warning

Lithium-ion batteries (LIBs) are widely used in industrial applications for energy storage and power supply. The failure of LIBs has attracted significant attention since severe accidents caused by thermal runaway. Electrolyte leakage in lithium-ion batteries (LIBs) represents a significant hidden risk to LIB systems and serves as an early indicator of potential thermal runaway. Current electrolyte leakage detection technologies often lack the sensitivity, cost-effectiveness, and longevity required for modern battery safety systems. To address this challenge, we investigate the phase transitions of leaked electrolytes and changes in particle size of ambient aerosols, and propose a pack-level optical electrolyte leakage sensor for early safety warning of LIBs failures in Industrial Internet of Things (IIoT) applications. Experiments demonstrate that the particle size of ambient aerosol increases rapidly due to phase change condensation of the leaked electrolyte vapor. Correspondingly, the light scattering efficiency of ambient aerosol increases, providing measurable indicators for electrolyte leakage monitoring. Our optical sensor can promptly detect leakage in the overcharging test, slightly surpassing the PPB gas sensor in response time while reducing cost to 1/10 due to mature commercial optical components and increasing lifespan 3 times according to the lifespan of core elements. Utilizing readily available commercial components, this method offers a high-sensitivity, cost-effective, and durable solution for improving safety in LIB systems.