Affiliation:
1. Department of Electrical and Electronic Engineering The Hong Kong Polytechnic University, Hung Hom Kowloon Hong Kong
2. Photonics Research Institute The Hong Kong Polytechnic University, Hung Hom Kowloon Hong Kong
3. Centre for Advances in Reliability and Safety Hong Kong Science Park, New Territories Hong Kong
4. Sustainable Energy and Environment Thrust The Hong Kong University of Science and Technology (Guangzhou) China
5. Department of Chemistry – Ångström Laboratory Uppsala University Uppsala Sweden
6. Department of Energy and Petroleum Engineering University of Stavanger Stavanger Norway
7. Department of Energy and Process Engineering Faculty of Engineering Norwegian University of Science and Technology Trondheim Norway
Abstract
AbstractGas evolution is fundamentally problematic in rechargeable batteries, and may lead to swelling, smoking, and device‐level failure. In laboratories, monitoring gas evolution can help understand dynamic chemical events inside battery cells, such as the formation of solid‐electrolyte interphases, structural change of electrodes, and electrolyte degradation reactions. However, gassing in commercial batteries, discrete or continuous, is not monitored due to a lack of compatible sensing technologies. Here we describe the working principles of four real‐time gas monitoring technologies for lithium‐ion batteries. Gassing mechanisms and reaction pathways of five major gaseous species, namely H2, C2H4, CO, CO2, and O2, are comprehensively summarized. Since pertinent progress has been made on the optical fiber‐based sensing of strain, pressure, and temperature of various battery cells recently, special emphasis has been given to fiber‐based laser spectroscopy for gas detection. The technical details of the fiber‐enhanced photothermal spectroscopy are compared with the four gas sensing technologies, and the commercialization possibilities are discussed. Owing to its small size, flexibility, and robustness, fiber‐based sensing technology can be compatible with almost all kinds of battery cells, showcasing their great potential in various applications. It is envisioned that gas‐event monitoring of rechargeable cells can be unlocked soon by utilizing fiber‐based gas spectroscopy.