Gas sensing for lithium-ion battery thermal runaway: an inorganic chemistry perspective.

Abstract

Thermal runaway in lithium-ion batteries is accompanied by stage-dependent evolution of electrolyte vapors and characteristic gases, providing a chemically informative window for early safety monitoring. This Perspective examines gas sensing for battery thermal runaway from an inorganic materials chemistry viewpoint. Rather than comparing sensing materials primarily by their reported response values, emphasis is placed on how the crystal structure, surface defects, interfacial electronic structure, and surface adsorption/reaction chemistry collectively determine gas-sensing behavior. Representative strategies, including crystal-facet regulation, defect engineering, noble-metal modification, and heterojunction construction, are discussed in terms of their influence on adsorption sites, catalytic reaction pathways, charge redistribution, and electrical transduction. It is further argued that the chemical differentiation of sensing surfaces is an important prerequisite for constructing sensor arrays capable of generating distinguishable multigas fingerprints, thereby reducing excessive reliance on increasingly complex data-analysis methods. Particular attention is given to the mismatch between sensing mechanisms established under controlled laboratory atmospheres and the dynamically evolving temperature, humidity, gas composition, and electrolyte-derived species encountered during battery thermal runaway. Finally, several unresolved key questions are identified, including how to design chemically distinguishable active sites to discriminate among coexisting thermal-runaway gases.

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