Widening the Range of Trackable Environmental and Health Pollutants for Li-Garnet-Based Sensors

Classic chemical sensors integrated in phones, vehicles, and industrial plants monitor the levels of humidity or carbonaceous/oxygen species to track environmental changes. Current projections for the next two decades indicate the strong need to increase the ability of sensors to sense a wider range of chemicals for future electronics not only to continue monitoring environmental changes but also to ensure the health and safety of humans. To achieve this goal, more chemical sensing principles and hardware must be developed. Here, a proof-of-principle for the specific electrochemistry, material selection, and design of a Li-garnet Li₇La₃Zr₂O₁₂ (LLZO)-based electrochemical sensor is provided, targeting the highly corrosive environmental pollutant sulfur dioxide (SO₂). This work extends the prime use of LLZO as a battery component as well as the range of trackable pollutants for potential future sensor-noses. Novel composite sensing-electrode designs using LLZO-based porous scaffolds are employed to define a high number of reaction sites, and successfully track SO₂ at the dangerous levels of 0–10 ppm with close-to-theoretical SO₂ sensitivity. The insights on the sensing electrochemistry, phase stability and sensing electrode/Li⁺ electrolyte structures provide first guidelines for future Li-garnet sensors to monitor a wider range of environmental pollutants and toxins.