Engineering semiconductor metal oxide nanostructures for chemiresistive gas sensors in early warning of battery thermal runaway

Thermal runaway in lithium-ion batteries poses significant safety challenges, often resulting in catastrophic fire and explosion incidents. Despite advancements in battery technology, the accurate detection and early warning of such events remain unresolved. This review examines the potential of semiconductor metal oxide (SMO)-based chemiresistive gas sensors to address critical battery safety challenges. Firstly, it describes the types of gases produced during battery thermal runaway (e.g., H₂, CO, CO₂, CH₄) and their production mechanisms. Secondly, it highlights recent progress in designing and functionalizing SMOs for gas detection purposes, including heteroatom doping, noble metal loading, heterostructure construction, and light-induced excitation. Thirdly, it discusses the sensing performance of different characteristic gases during battery thermal runaway. Finally, it explores the integration of SMO materials onto MEMS sensors and the utilization of machine learning in gas sensing applications to enhance real-time safety monitoring in battery systems. This review underscores the urgent need for efficient and reliable semiconductor metal oxide sensors strategically integrated into battery management systems to mitigate thermal runaway risks. Future advances will hinge on enhancing sensing performance (e.g., selectivity, long-term stability) while coupling SMO sensors with machine learning to enable practical and intelligent early-warning capabilities.