Gas sensing technology as the key to safety warning of lithium-ion battery: Recent advance

New energy resources applied in electricity generation have attracted great attention nowadays, especially in the auto industry. Because of the high energy density and enduring use life, the lithium-ion battery has been considered an appropriate electrical power resource for electric vehicles. However, cells with high energy density are more inclined to have thermal runaway problems, which can cause severe damage to battery performance. Sensors based on pressure and temperature have been applied in safety early warning and monitoring of thermal runaway, which do not perfectly meet the requirement of global technical regulation that passengers need to be warned before serious accidents. Therefore, gas detection for early safety warning of lithium-ion batteries can be an effective method to control and prevent thermal runaway problems. This review aims to summarize the recent progress in gas sensing of thermal runaway gases. We discuss the advantages and disadvantages of different types of sensors. Gas evolution mechanism in lithium-ion batteries is also proposed. It is expected that this review will inspire the development of battery safety early warning. More stable conditions for high energy density systems could be provided with such gas detection strategies and devices.