Till now, the prevention and inhibition of the thermal runaway in lithium-ion batteries (LIBs) is still a challenge. Additive fine water mist is a promising response technology addressing such issues. In this paper, the enhancement effect of four nonionic surfactants, i.e. Tween-20, Silok (R) 2235, FC-7430, and TX-100, and carbon dot additives (SQDs) on the thermal runaway suppression of 26650 battery by fine water mist was experimentally studied using an intelligent small-scale lithium battery thermal runaway suppression experimental platform, which was designed and constructed based on the voltage drop and temperature data during the process thermal runaway of 26650 LIB with different SOC. The enhancement effect of these additives on the inhibition of fine water mist were evaluated using the Tt, Tm, and cooling rate of the battery after thermal runaway as indicators. The enhancement effect of surfactants on the inhibition of fine water mist was related to the surface tension and foaming properties of their mixed solution, that was, the lower the surface tension and foaming ratio, the better the enhancement effect. The enhancement effect of SQDs on the inhibition of fine water mist was attributed to its ability to quench free radicals, the cooling and suffocating effect. An efficient and environmentally friendly, 600 ppm Silok (R) 2235 & 1200 ppm CQDs composite additive fine water mist was obtained at last. This study would improve the prevention and emergency response capabilities for lithium-ion battery thermal runaway accidents, and promote the healthy development of the lithium-ion battery industry.

The safety research of thermal runaway propagation (TRP) has become the current focus with the wide application of lithium-ion batteries (LIBs). It is crucial to design and utilize different combinations of thermal insulation materials to prevent TRP. In this study, an independent experimental platform for investigating TRP behavior in 26,650 LIB modules were established, considering various electrical connections and aerogel insulation placement. The collected and analyzed data include TRP behavior, temperature, mass loss, and heat release rate, aiming to explore the influence of aerogel felt positioning on TRP characteristics. The findings reveal that parallel modules not only exhibit an earlier onset of TRP than other battery systems but also pose a higher risk under various electrical connections. The positioning of the aerogel felt significantly influences the speed of TRP. Placing an aerogel felt between batteries postpones the onset of TRP in the battery module regardless of the electrical connection. Furthermore, situating an aerogel felt between batteries notably diminishes overall heat release during TRP for both series and non-electrically connected batteries. Combining the placement of aerogel felts at the top and middle positions can mitigate harm from TRP in a parallel battery system. This study proposes targeted preventive strategies for diverse electrically connected battery systems and identifies specific aerogel configurations capable of effectively suppressing TRP in the battery module. ✔ Various combinations of aerogel felt have a significant impact on the TRP velocity in battery packs. ✔ Parallel battery systems exhibit a higher susceptibility to TRP compared to other configurations. ✔ The heat transfer during TRP is analyzed across different battery systems.

Highly active catalysts remain a vital issue for the Fenton-like degradation of polychlorinated phenols by H2O2. To this question, Cu0-Fe3O4 nanocatalysts functionalized with hydroxyl and carboxyl groups were prepared in this paper, and the Cu0-Fe3O4-H2O2 Fenton-like system was constructed and investigated for the degradation of chlorophenols. The results showed that Cu0 could greatly improve the oxidation activity of the system. 0.04 g Cu0-Fe3O4 composite (Fe/Cu = 3/1 mol/mol) could activate 20 μL H2O2 (30

In the context of rapid urbanization, urban security has a huge impact on social stability, such as huge property losses and casualties. Especially in extreme weather conditions, disasters will increase, thus the study of urban safety early warning systems is necessary. Firstly, this paper introduces the current situation and problems of urban security. Then, the urban safety early warning systems and emergency response mechanisms under snowstorm conditions are established and discussed according to the current situation. Finally, this paper puts forward suggestions and measures for the urban safety emergency rescue guarantee mechanism in snowstorm conditions.

This study proposed a method for identifying traffic accident (TA) hotspots. The method combines kernel density estimation (KDE) with network kernel density estimation (NKDE). The hotspots identified through NKDE can be overlaid on the high-risk areas (hot zones) identified using planar KDE, resulting in accurate hotspot identification. The research site was Zhenjiang City in Jiangsu Province, China; data on 410 fatal traffic accidents from 2017 to 2020 were collected. An average nearest neighbour (ANN) ratio (0.563) was obtained using the global auto nearest neighbour distance method; thus, the fatal TAs had a cluster-type distribution in the city. Subsequently, the maximum clustering distance (7812.842591 m) in the research site was analysed using Ripley's K-function, which yielded a reasonable KDE bandwidth and enabled identifying the distribution of hot zones for fatal TAs. Precise hotspot identification was achieved by overlaying the results of NKDE-based analysis in these hot zones. The proposed method was verified using data on 131 fatal TAs during January to July 2021. The results revealed that, in Zhenjiang City, the identification rate for hot zones and hotspots in hot zones was 71.75% and 38.29%, respectively, and the overall hotspot identification rate was 27.48%, demonstrating the method's ability to relatively accurately identify hotspot locations, information that can help traffic authorities implement preventive measures.

Water mist with additives is a promising emergency control technology for the lithium-ion battery's thermal runaway. Developing efficient, green, and environmental-friendly additive is a key issue to the technology. Here, using 18,650 batteries as the experimental object, three different suppression mechanism additives, i.e. sodium dodecyl benzene sulfonate (SDBS), sodium chloride (NaCl), and soy protein, were studied and discussed after optimizing the condition of water mist generated with different Here, using 18,650 batteries as the experimental object, three different suppression mechanism additives, i.e. sodium dodecyl benzene sulfonate (SDBS), sodium chloride (NaCl), and soy protein, were studied and discussed after optimizing the condition of water mist generated with different compressed air. The battery thermal runaway process concluded four stages, and the initial stage of explosion, i.e. the safety valve broke through companying with some noise and gases spilling out, was a typical phenomenon that suggested the beginning of thermal runaway. The water mist generated with optimized air pressure of 0.2 to 0.25 MPa, the droplet SMD size was 71-89 & mu;m, could effectively suppress the battery thermal runaway, decrease T2 quickly from about 700 & DEG;C to no more than 413 & DEG;C, and reduce the cooling time from above 1000 s to no more than 203 s. Although the mechanism of the three additives was different, all of them could evidently enhance the suppression effect of water mist on the lithium-ion battery's thermal runaway. Especially, the addition of 1.5% soy protein to water mist could decrease greatly both the flame temperature and the battery's surface temperature, and shorten 63% cooling time comparing to the pure water mist. The results showed that soy protein was an efficient and environmental-friendly additive for water mist to inhibit the thermal runaway of lithium-ion battery and had good potential practical application value. The in-depth research and analysis of SDBS and NaCl would provide basis data for the development of compound additive.

The mixed-valent magnetite (Fe3O4) played a critical role in H2O2-based Fenton-like system for the removal of chlorophenols, but high activity and cycle stability of the Fe3O4-based catalysts are still a huge challenge. Herein, a series of surface hydroxyl-and carboxyl-modified Ag0/Fe3O4 nanocomposite catalysts were prepared and used to activate H2O2 for degradation chlorophenols pollutants. Under the optimized condition, nearly 100% degradation ratio were achieved within 2-30 min for 2,4-dichlorophenol, 2,3dichlorophenol, 3,4-dichlorophenol, 2,4,6-trichlorophenol, p-nitrophenol, and 98% degradation ratio for 2,5-dichlorophenol, 2,6-dichlorophenol and 3,5-dichlorophenol,. Moreover, wide pH applicability was obtained for the Ag0/Fe3O4-H2O2 system, where 95% degradation ratio of 2,4-dichlorophenol was still obtained at pH 6.0. The excellent activity of Ag0/Fe3O4 catalyst can be ascribed to the incorporation of Ag0 nanoparticles that accelerated the Fe(III)/Fe(II) transformation with the assistance of surface hydroxyl and carboxyl groups. Detailed mechanism study indicated a pseudo-second-order kinetic model, where the oxidative degradation and reductive degradation pathways coexisted in the system. The surface modified Ag0/Fe3O4-H2O2 provide a practical catalyst system for the removal of phenol contaminants with high reaction rate, wide pH adaptability, and validity for a series of chlorophenols. (c) 2022 Elsevier Inc. All rights reserved.