Cutting-edge gas sensor design for monitoring thermal runaway in lithium-ion batteries: a critical review

Thermal runaway (TR) in lithium-ion batteries (LIBs) poses significant safety risks due to its potential to trigger fires and explosions. Early warning of battery TR through gas sensing has emerged as a promising strategy for hazard mitigation. However, comprehensive reviews critically summarizing recent progress in advanced gas sensing technologies remain scarce. To fill this void, we present a critical review consolidating state-of-the-art advancements in gas sensing for TR early warning. This review first overviews the fundamentals of gas sensing for TR monitoring, encompassing thermodynamics and kinetic principles of gas evolution alongside current gas sensing technologies. We then comprehensively explored multi-scale engineering methods, spanning material innovations, device configurations, and system-level integration, with an emphasis on cutting-edge techniques like additive manufacturing and data-driven design frameworks. Future research priorities are identified, including the enhancement of gas selectivity and environmental robustness, the development of machine learning-driven intelligent gas sensing networks, and the establishment of standardized protocols for practical deployment. By integrating interdisciplinary insights derived from materials science, electrochemistry, and embedded systems engineering, this review is positioned to offer actionable guidelines for advancing scalable and reliable gas-sensing solutions toward boosted LIB safety.