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Currently, it is significant to study the fire suppression of battery modules in energy storage stations. In this work, the combustion tests of a single cell and battery module were conducted on the 243 Ah lithium iron phosphate battery. Meanwhile, the fire extinguishing effect of C6F12O on large-scale battery module fire was verified under a real-scale fire scenario. Results show that the thermal runaway process of a single cell can be divided into four stages. The thermal runaway process had an "incubation period" in stage II, which was suitable for early warning and fire extinguishing. Thermal runaway can propagate within the battery body and the thermal runaway propagation time was 121 s. Thermal runaway propagation can occur in the battery module, which is much more aggressive and risky than a single cell. It needed around 50 kJ to 60 kJ to support the thermal runaway propagation between an adjacent cell in the battery module. Furthermore, The C6F12O has good fire extinguishing and cooling effect, which can successfully inhibit the thermal runaway propagation in the battery module. Meanwhile, when the designed fire extinguishing concentration of C6F12O is reached in the battery pack, the subsequent battery will not be ignited even if the safety valve is opened. [ABSTRACT FROM AUTHOR]

As an advanced energy storage medium, lithium-ion batteries (LIBs) are being used in aircraft and other aviation fields owing their unique advantages. The thermal runaway (TR) behaviours of LIBs used in aircraft are more complicated and dangerous due to the special operating environments, such as low pressure and enclosed environments. Therefore, a special test platform was designed to study the effect of low pressure on the TR characteristics of 2.2 Ah 18,650 type LIBs in this work. Some critical parameters of TR were obtained, such as onset temperature of TR, maximum temperature, voltage drop time, pressure, and the explosion limit of gases, etc. The results show that with the pressure increasing, the TR onset temperature, maximum temperature, and pressure increase in the test chamber, and the voltage drop time postpones. In addition, the amount of released gas and the explosion limitation range of gases increase with the decrease of the initial pressure. This means it's easier to occur but with weaker hazard of TR at lower pressure. Besides, the SEM results reveal that deformation and structural damage of cathode materials, which is attributed to the increase of the large amount of gas released at the electrode material level. These results provide the basis for the safe application and storage of LIBs in a confined space under different pressures. [ABSTRACT FROM AUTHOR]

Semi-solid lithium slurry battery is an important development direction of lithium battery. It combines the advantages of traditional lithium-ion battery with high energy density and the flexibility and expandability of liquid flow battery, and has unique application advantages in the field of energy storage. In this study, the thermal stability of semi-solid lithium slurry battery material system was investigated for the first time employing C80 micro-calorimeter. In this new electrode material system, the heat generation of the electrolyte is the decisive factor for its thermal stability. Then, the measurement of in-situ dynamic cycle heat generation of semi-solid lithium slurry battery indicated a lower heat generation than traditional lithium-ion battery. What's more commendable is that its electrochemical performance is basically the same as traditional lithium-ion battery. In addition, through the HPPC test, the mechanism of semi-solid lithium slurry battery cycle heat generation was explained. So, in this work, a preliminary evaluation on the safety and cycling stability of semi-solid lithium slurry battery is carried out. The electrochemical performance test affirms the application prospects of semi-solid lithium slurry battery, and the evaluation on the fire safety provides a reference for the future industrial applications of semi-solid lithium slurry battery. [ABSTRACT FROM AUTHOR]

Lithium ion batteries (LIBs) have become the dominate power sources for various electronic devices. However, thermal runaway (TR) and fire behaviors in LIBs are significant issues during usage, and the fire risks are increasing owing to the widespread application of large-scale LIBs. In order to investigate the TR and its consequences, two kinds of TR tests were conducted triggered by overheating and overcharging ways. The cells are 228 Ah with LiFePO4 as cathode. The TR and fire behaviors were studied comprehensively from the aspect of experimental photographs, temperature characteristics, heat release rate (HRR), total heat release (THR), voltage and mass loss variation. The effects of different triggers were investigated. Under the two trigger conditions, the LIBs did not self-ignite and instead only release a large amount of gases or aerosols. With external ignition sources, the combustion process can be classified into four stages. The relationship between TR and fire behaviors related to the two conditions are discussed, respectively. Compared with overheating, the batteries burn more violently and have higher fire risks during overcharging tests. The work is supposed to provide valuable fundamental data and theory guidance for early warning technology and fire protection. [ABSTRACT FROM AUTHOR]

Nonflammable electrolytes are promising substitutes for the state-of-the-art carbonate-based electrolytes in order to directly enhance the safety characteristics of lithium ion batteries. Combination of trimethyl phosphate (TMP) and a fluorinated ether of 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (FEPE) is designed to formulate nonflammable electrolytes. The reformulated electrolytes of 1 mol/L LiPF6/TMP + FEPE (9:1, 8:2 and 7:3, w/w) are totally nonflammable. The FEPE solvent has higher oxidative stability and the FEPE-containing electrolytes have better separator wettability than the pure TMP electrolyte (1 mol/L LiPF6/TMP). The improved oxidative stability and separator wettability can enhance electrochemical stability of electrolyte on high-voltage cathode LiNi0.5Mn1.5O4. In Li4Ti5O12/LiNi0.5Mn1.5O4 cells, the FEPE-containing electrolyte exhibits the better cycling stability than the pure TMP electrolyte, and the solvent composed of TMP + FEPE (8:2) is the optimal ratio. The Li4Ti5O12/LiNi0.5Mn1.5O4 cell with the optimal electrolyte exhibits better rate capability because of the reduced polarization and improved oxidation stability. This work reveals the effect of fluorinated ethers on separator wettability of TMP-based nonflammable electrolytes and high-voltage applications. [ABSTRACT FROM AUTHOR]

To further understand the thermal properties of lithium ion batteries, in situ measurement and calculation of the heat generation under operating condition are conducted. In this work, a novel micro-calorimeter with high accuracy is applied to study the heat flow of the LiNi0.5Co0.2Mn0.3O2/Li half cell. The dynamic heat generation and corresponding electrochemical data are detected out under isothermal environment from 30°C to 70°C with different current rates (0.2, 0.4, 0.6, 0.8 and 1.0 C) and electrode thicknesses (400, 200 and 100 μm). In addition, heat generation rate is calculated based on the measurement of entropy coefficient and internal resistance. It is found that the heat generation rises with the increase of thickness and current rate, due to concentration polarization and electrochemical polarization, respectively. The lithiation process is more sensitive to changes in current rate than delithiation. Appropriately increasing the temperature can improve the activity of material and reduce the energy consumption of the battery. Besides, the contribution of reversible heat to the overall heat generation should be taken into account especially at a lower current rate (< 0.5 C). The detailed analysis of heat generation and electrochemical performance can provide accurate data for thermal management systems. [ABSTRACT FROM AUTHOR]