Highly Sensitive EMC Semiconductor Gas Sensor to Overcome Thermal Drift for Thermal Runaway Warning of Lithium Batteries

At present, the thermal runaway of lithium batteries is an important cause of the safety risk in new energy vehicles. The detection of volatiles by gas sensors for early warning is a novel and promising approach, but it faces challenges such as stability issues caused by sensor baseline thermal drift and sensitivity issues caused by insufficient activity. In this article, a highly sensitive ethyl methyl carbonate (EMC) gas sensor to overcome thermal drift is proposed, which is developed based on uniformly dispersed MnSnO3–x/NiO nano-sensitive materials with flower-like hierarchical structure. The resistance change of this sensor to 200 ppb EMC is 6.9%. The standard deviation of the gas sensing response to 10 ppm EMC under temperature changes of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$150~^{\circ }$ </tex-math></inline-formula>C, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$180~^{\circ }$ </tex-math></inline-formula>C, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$210~^{\circ }$ </tex-math></inline-formula>C, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$240~^{\circ }$ </tex-math></inline-formula>C, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$270~^{\circ }$ </tex-math></inline-formula>C is 3.70%, with a coefficient of variation (CV) of 4.15%. The standard deviation of the long-term stability test within one month is 3.15%, and the CV is 3.29%. This type of sensor has good sensitivity, stability, and consistency, which can effectively overcome the response drift caused by the baseline thermal drift, detecting EMC volatiles to warn lithium battery thermal runaway. It was found that the improved sensitivity was attributed to the catalytic and heterojunction effects produced by the introduction of bimetallic amorphous MnSnO<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${}_{3-X}$ </tex-math></inline-formula>. The excellent sensing thermal drift suppression is attributed to the grain boundary barriers and electronic properties of the unique flower-graded NiO. The good stability and consistency are attributed to the well-dispersed structure and stable properties of the sensitive materials. This work realizes the coordination of sensitivity and stability of EMC semiconductor gas sensors based on a 3-D hierarchical heterogeneous synergistic strategy, which provides a novel approach for the early warning of thermal runaway in lithium batteries.