This study presents a systematic evaluation of extinguishing agents against lithium-ion Battery Energy Storage Systems (BESS), specifically examining thermal runaway propagation in small domestic system (8 kWh). Five distinct suppression methods were evaluated: water mist, encapsulator agent (water mist with proprietary encapsulator), carbonate agent (water mist with ammonium bicarbonate), mixed agent (containing boron compounds and surfactants), and liquid nitrogen.
Performed experiments revealed significant differences between suppression methods. Water mist and encapsulator agents demonstrated better performance, extending propagation delay times by 179% and 167%, respectively, compared to control tests without a suppression method. Registered maximum temperatures varied across methods from 780° to 890 °C. However, none of the tested methods prevented thermal runaway propagation entirely and were able to save the system from being destroyed.
Critical safety concerns emerged regarding vapour cloud production, which correlated strongly with cooling effectiveness (r = 0.87) but increased explosion risks. Statistical analysis confirmed significant method-dependent differences (p < 0.001), with water mist and encapsulator agents reducing thermal runaway hazard ratios by over 70%. These results indicate that current suppression technologies can delay but not prevent thermal runaway propagation. Findings emphasize the need for integrated approaches combining efficient cooling with vapour management strategies, particularly for residential BESS installations.
Lithium-ion batteries (LIBs) have revolutionized energy storage, offering high energy and power densities, long cycle lives, and low self-discharge rates. Their widespread adoption spans portable electronics, electric vehicles, and grid-scale energy storage. However, the very properties that make LIBs attractive also present safety challenges, most notably the risk of thermal runaway leading to fire and potential explosions. This phenomenon, triggered by abuse scenarios such as overcharging, over-discharging, short circuits, or external heat, involves a rapid and uncontrolled increase in temperature and pressure within the battery cell. The presence of flammable organic liquid electrolytes further exacerbates fire hazards, facilitating rapid propagation throughout the battery pack.
The consequences of LIB fires can be devastating and endanger life, property, and the environment. High-profile incidents involving LIB fires in various applications underscore the urgent need for effective fire safety measures. These incidents highlight the critical importance of understanding the mechanisms of LIB fires and developing strategies for their prevention, mitigation, and suppression. A comprehensive approach for the fire safety of LIBs involves multiple layers of protection. This includes enhancing the inherent safety of battery key components (electrolyte, active materials, binders, separator, additives) and cell design, implementing robust battery management systems to prevent and detect thermal runaway, and developing effective fire suppression techniques.
Although advancements in materials science and BMS technology have improved battery safety, effective fire suppression remains a critical area of ongoing research. Traditional fire extinguishing agents, such as water and foam, may not be ideal for LIB fires owing to the unique characteristics of these batteries. Water, while effective in cooling some fires, can react with the electrolyte in LIBs (additional formation of HF), potentially exacerbating the situation. The high temperature and pressure generated during thermal runaway can also hinder the penetration and effectiveness of conventional agents. Moreover, any casing, i.e. BESS enclosure or electric vehicle pack and chassis on top, may hinder the penetration of the agent into the affected spot.
Consequently, specialized fire suppression agents and techniques tailored to LIB fires are essential. Researchers are actively exploring various approaches, including novel extinguishing agents, cooling methods, and fire-resistant materials. Water mist systems, delivering finely atomized water droplets for effective cooling and flame suppression, and encapsulator agents, which form a barrier to prevent oxygen from reaching the fire, are among the most scrutinized solutions.
Several tunnel fire detection and fighting systems are currently available in the market, each with its own advantages and disadvantages. Although no single system is perfect, the water mist system is one of the top-performing conventional tunnel fire suppression systems available. Other approaches include the use of inert gases, such as nitrogen or argon, to displace oxygen and develop fire-resistant electrolytes and battery casings.
Recent advances in fire-suppressing agents for mitigating LIB fires have focused on the development of composite materials with enhanced properties. These materials offer advantages such as environmental friendliness, high heat dissipation rates, electrical insulation, and prevention of re-ignition. A comprehensive review of various fire-extinguishing agents highlights their distinct characteristics and effectiveness in addressing LIB fires by considering factors such as insulation, toxicity, fire suppression speed, reactivity with fire sources, degradation capacity, and corrosion.
Despite these developments, a comprehensive understanding of suppression effectiveness across different battery configurations and failure modes is limited. This study addresses this gap by evaluating multiple suppression agents against lithium-ion battery fires, with particular focus on their ability to prevent thermal runaway propagation in an emulated domestic energy storage system.
The research objectives of this study were to:
1. Evaluate the effectiveness of water mist, encapsulator agents, carbonate-based suppressants, and liquid nitrogen in extinguishing LIB fires.
2. Assess these agents’ capability to prevent thermal runaway propagation.
3. Quantify key performance metrics, including extinguishment time, cooling rate, and re-ignition prevention. This paper presents experimental results from controlled tests, providing quantitative data to inform the development of more effective fire safety protocols for lithium-ion battery systems.
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