Protection strategy fundamentals, the limiting oxygen concentration to be achieved, system configuration and sizing are defined proving the feasibility of the application of VABs as oxygen reduction system. This novel solution is presented and discussed with reference to the safety framework including standards, firefighting systems, batteries features, experimental findings and incidental experience. A novel concept to prevent Li-ion battery fires in grid installations could be represented by the integration with Vanadium-air flow batteries (VAB), a hybrid energy storage system configuration capable of fire prevention through permanent oxygen reduction in the protected volume. Thermal runaway results as the recurring high impact failure effect. Over 20 fire incidents in grid systems were reported during the last years in Korea and United States, with negative repercussions in market and safety. Installed capacity forecasts suggest a strong growth in the next years with renewable energy utilization to meet decarbonization purposes. Li-ion battery is the most diffused technology among electrochemical energy storage systems. The results may contribute significantly to failure detection and improvement of battery safety. The chosen gas sensor can detect H2 produced by unwanted electrolysis and electrolyte vapor and gases produced by degassing of state-of-the-art LIBs. The experiments show that battery failure detection with gas sensors is possible but depends highly on the failure case. The response of several commercially available gas sensors is tested in four battery failure cases: unwanted electrolysis of voltage carrying parts, electrolyte vapor, first venting of the cell and the TR. In this study, gases produced during battery failure before and during a thermal runaway (TR) are investigated in detail and the use of different gas sensors as early detectors of battery incidents is tested and proposed. This regulation can hardly be fulfilled with state-of-the-art battery monitoring. New regulations (GB 38031-2020) require a warning for passengers at least five minutes before serious incidents. In case of a defect inside or outside the cell, serious safety risks are possible including extensive heat generation, toxic and flammable gas generation, and consequently fire and explosion. Safety for automotive lithium-ion battery (LIB) applications is of crucial importance, especially for electric vehicle applications using batteries with high capacity and high energy density. The implications for off gas monitoring will be investigated in several contexts including life extension, second life batteries, and the use of batteries in new environments with varying safety considerations.
In addition, with enough prior warning from the sensor there is a desire to determine whether it provides suitable control at the fringes of battery performance and also acts as a state of health sensor. The remainder of the program will address whether the sensor can detect off gas prior to significant failure events and whether battery functionality can be preserved after abuse events. Early results indicate the sensor can detect off gas prior to thermal events. The work presented summarizes the early results of an ARPA-e AMPED funded study (2012-2015) to qualify a novel sensor for off gas detection. Recent safety incidents involving Li-based battery chemistries have occurred across automotive, marine, electric grid, and aviation sectors and indicate a need to understand battery failure and the implications for control of the thermal event and the off gas hazard. Off gas from Li-ion batteries is becoming a growing concern because the volatile organics emitted are flammable and their unpredictable release represents a safety risk.
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