Batteries are widely used in energy storage systems (ESS), and thermal runaway in different types of batteries presents varying safety risks. Therefore, comparative research on the thermal runaway behaviors of various batteries is essential. This study investigates the thermal runaway characteristics of sodium-ion batteries (NIBs), lithium iron phosphate batteries (LFP), and lithium-ion batteries with NCM523 and NCM622 cathodes. The experiments were conducted in a nitrogen-filled constant-volume sealed chamber. The results show that the critical surface temperatures at the time of thermal runaway are as follows: LFP (346 °C) > NIBs (292 °C) > NCM523 (290 °C) > NCM622 (281 °C), with LFP batteries exhibiting the highest thermal runaway critical temperature. NIBs have the lowest thermal runaway triggering energy (158 kJ), while LFP has the highest (592.8 kJ). During the thermal runaway of all four battery types, the primary gases produced include carbon dioxide, hydrogen, carbon monoxide, methane, ethylene, propylene, and ethane. For NCM622 and NCM523, carbon monoxide is the dominant combustible gas, with volume fractions of 35% and 29%, respectively. In contrast, hydrogen is the main flammable gas for LFP and NIBs, with volume fractions of 44% and 30%, respectively. Among these, NIBs have the lowest lower flammability limit (LFL), indicating the highest explosion risk. The thermal runaway characteristics of 50 Ah batteries provide valuable insights for battery selection and design in energy storage applications.

Lithium-ion batteries (LIBs) generate substantial gas during the thermal runaway (TR) process, presenting serious risks to electrochemical energy storage systems in case of ignition or explosions. Previous studies were mainly focused on investigating the TR characteristics of Li(Ni_xCo_yMn_z)O₂ batteries with different cathode materials, but they were conducted in isolation. In this study, the thermal runaway characteristics of prismatic cells that use Li(Ni_xCo_yMn_z)O₂ (with x ranging from 0.33 to 0.9) cathode materials in an inert environment, which are commonly used or proposed for energy storage applications, are examined. The findings of this research show that the normalized gas generation rate remains consistent, regardless of the battery capacity or experimental chamber volume, with a value of 0.1 ± 0.03 mol∙Ah^⁻1. High-capacity cells have short jetting durations, and a high nickel content leads to increased mass loss rates. The flammability limits of the gases expelled during thermal runaway, represented by the lower flammability limit (LFL), remain stable at 8 ± 1.8 % with minimal variations. However, the upper flammability limit (UFL) varies significantly, ranging from 30 % to 60 %. Increasing the battery capacity or reducing the experimental chamber volume increases the explosion index. The explosive, combustibility, and jetting duration characteristics of the emitted gases from five different battery chemical compositions provide valuable insights for risk assessment in future electrochemical energy storage systems.

Lithium batteries are widely used in fields such as engineering micro-machines, robotics, and transportation. However, safety issues caused by battery thermal runaway limit their further promotion. This study used a sealed heating pressure chamber (SHPC) to perform “heat-wait-seek (HWS)” stepwise heating on a 50 Ah lithium iron phosphate (LiFePO₄) battery to trigger thermal runaway. It was found that the state of charge (SOC) has a significant impact on the safety of the battery. There was no significant correlation between the valve opening temperature (T₁) and the temperature at which the battery’s thermal runaway rapidly self-heats (T₂) and SOC. However, as SOC increased, the maximum temperature (T₃) of the battery’s thermal runaway increased, reaching up to 357.4 °C. The mass loss rate due to thermal runaway increased with SOC. The critical point of the battery’s safety valve was essentially independent of SOC and was mainly influenced by temperature. After thermal runaway, the mixed gas was passed through a gas chromatograph (GC) to detect its composition. When the SOC was below 50%, the total gas production from thermal runaway increased slowly (0.68–0.90 mol). Above 50% SOC, the total gas production from the battery increased sharply (at 75% SOC, 1.17504 mol; at 100% SOC, 2.33047 mol). Among these gases, the amount of H₂ increased sharply with SOC (from 0.01 mol at 0% SOC to 0.93 mol at 100% SOC), while the amount of CO₂ remained almost constant. Considering the inerting effect of CO₂ in the gas produced during thermal runaway of LiFePO₄ batteries, the lower flammability limit of the mixed gas increased as SOC decreased (from 6.91% at 100% SOC to 55.43% at 0% SOC). The risk of explosion during thermal runaway of high SOC batteries significantly increased. Notably, within the SOC range of 25% to 100%, the flammable range remained stable at 34–43%, but at 0% SOC, it sharply dropped to 0.5%. Therefore, batteries that are deeply discharged have higher safety.

Lithium-ion batteries (LIBs) are plagued by risks of combustion and explosion during thermal runaway (TR), which hinder their broader applications. Currently, there is limited research on thermal runaway experiments for batteries with a capacity exceeding 200 Ah. In this study, a non-commercial 256 Ah prismatic battery was utilized, featuring Li (Ni0.8Mn0.1Co0.1)O2 as the cathode material and silicon-doped graphite as the anode material. The investigation focused on the thermal runaway characteristics of the battery under 100% state of charge (SOC) conditions. Three repetitive thermal runaway experiments were conducted within a 1000L lithium battery constant volume test chamber (AEC) under a nitrogen environment. Temperatures at various points within the battery were recorded during the experiments, and high-speed cameras were employed to capture moments of thermal runaway. The research findings are as follows: 1) The ejection velocity of smoke at the instant of safety valve opening was measured at approximately 140 m/s, while the velocity of the ejected flame was approximately 55 m/s. 2) Within an extremely short time range after safety valve opening, the temperature at the safety valve nozzle reached a peak value of 701.8°C ± 42 C. 3) The average duration of ultra-high-speed ejections was measured at 5.0 ± 1.6 s, high-speed ejections lasted for 11.9 ± 2.7 s, and slow-speed ejections exhibited an average duration of 21.6 ± 3.7 s, resulting in a total ejection duration of 36.2 ± 4.7 s. This study provides valuable insights into the original state of the jetting process during thermal runaway in high-capacity LIBs and offers certain guidance for BTMS design.

With the widespread adoption of battery technology in electric vehicles, there has been significant attention drawn to the increasing frequency of battery fire incidents. However, the jetting behavior and expansion force during the thermal runaway (TR) of batteries represent highly dynamic phenomena, which lack comprehensive quantitative description. This study addresses this gap by employing an enhanced experimental setup that synchronizes the video timing of cameras with a signal acquisition system, enabling the multidimensional quantification of signals, such as images, temperature, voltage, and pressure. It also provides a detailed description of the jetting behavior and expansion force characteristics over time for Li(Ni_0.8Co_0.1Mn_0.1)O₂ batteries undergoing thermal runaway in an open environment. The results from three experiments effectively identify key temporal features, including the timing of the initial jetting spark, maximum jetting velocity, jetting duration, explosion duration, and patterns of flame volume variation. This quantitative analytical approach proves effective across various battery types and conditions. The findings could offer scientific foundations and experimental strategies for parameter identification in fire prevention and thermal runaway model development.

In response to the instability fluctuations and erosion characteristic changes in pantograph-catenary system (PCS) arcs induced by humidity variations in an open environment, a single-variable controlled experimental approach based on multi-source data fusion is proposed. This study innovatively establishes a humidity-controlled reciprocating current-carrying arc initiation test platform, integrating digital image processing with the dynamic analysis of multi-physics sensor signals (current, voltage, temperature). The study quantitatively evaluates the arc motion characteristics and the erosion effects on the frictional contact pair under different relative humidity levels (30%, 50%, 70%, and 90%) with a DC power supply (120 V/25 A). The experimental data and analysis reveal that increasing humidity results in higher contact resistance and accumulated arc energy, with arc stability first improving and then decreasing. At low humidity, arc behavior is more intense, and the erosion rate is faster. As humidity increases, the electrode wear transitions from adhesive wear to electrochemical wear, accompanied by copper transfer. The results suggest that the arc stability is optimal at moderate humidity (50% RH), with a peak current-carrying efficiency of 66% and a minimum loss rate of 14.5%. This threshold offers a vital theoretical framework for the optimization and risk assessments of PCS design.