Battery safety is influenced by various factors,with thermal runaway being one of the most significant concerns.While most studies have concentrated on developing one-time,self-activating mechanism for thermal protect...Battery safety is influenced by various factors,with thermal runaway being one of the most significant concerns.While most studies have concentrated on developing one-time,self-activating mechanism for thermal protection,such as temperature-responsive electrodes,and thermal-shutdown separators,these methods only provide irreversible protection.Recently,reversible temperature-sensitive electrolytes have emerged as promising alternatives,offering both thermo-reversibility and self-protective properties.However,further research is crucial to fully understand these thermal-shutdown electrolytes.In this study,we propose lower critical solution temperature(LCST)phase behavior poly(benzyl methacrylate)/imidazolium-based ionic liquid mixtures to prepare temperature-sensitive electrolytes that provide reversible thermal shutdown protection of batteries.This electrolyte features an appropriate protection temperature(~105℃)and responds quickly within a 1 min at 105℃,causing cells to hardly discharge as the voltage suddenly drops to 3.38 V,and providing efficient thermal shutdown protection within 30 min.Upon cooling back to room temperature,the battery regains its original performance.Additionally,the electrolyte exhibits excellent cycling stability with the capacity retention of the battery is 91.6%after 500 cycles.This work provides a viable solution for preventing batteries from thermal runaway triggered by overheating.展开更多
Subway fires often cause significant casualties and property losses.There are some special bidirectional coupling scenarios during subway fires,such as firefighters moving against the evacuation flow to extinguish fir...Subway fires often cause significant casualties and property losses.There are some special bidirectional coupling scenarios during subway fires,such as firefighters moving against the evacuation flow to extinguish fires,emergency managers going to the fire scene to respond to emergencies,or other similar scenarios.How to evacuate passengers quickly and enable responders to enter the fire scene has become a big challenge for subway fire evacuation and response.The core goal is to reduce the degree of mutual interaction between these people moving in opposite directions.In this study,the impact of counterflow individuals and proactive avoidance behavior on evacuation processes was investigated through experiments and simulations.The Fire Dynamic Simulator was used to simulate the development of a fire scenario to determine the available safe egress time.Micro-evacuation experiments were conducted to obtain actual evacuation parameters,such as the speeds of different objects.With these parameters as input,a macro subway fire scenario was built to simulate the bidirectional evacuation process.Consistent conclusions were obtained from the experiments and evacuation simulations.The results indicate that the overall evacuation time increases with the number of retrograders.Proactive avoidance behavior can effectively reduce the travel time of counterflow individuals,but it causes slight delays for forward-moving evacuees.An optimization strategy was implemented through conductor guidance.All passengers can successfully evacuate under the optimization strategy,with a 25.3%improvement in overall evacuation time.This research provides some insights into the coordinated evacuation and emergency response during subway fires or similar scenarios.展开更多
基金funded by the National Natural Science Foundation of China(no.22075155)the Zhejiang Provincial Natural Science Foundation of China(No.LY24B030002)+2 种基金Ningbo Natural Science Foundation(2023J089)the China Scholarship Council(CSC)the Ningbo Science and Technology Bureau(2024QL036).
文摘Battery safety is influenced by various factors,with thermal runaway being one of the most significant concerns.While most studies have concentrated on developing one-time,self-activating mechanism for thermal protection,such as temperature-responsive electrodes,and thermal-shutdown separators,these methods only provide irreversible protection.Recently,reversible temperature-sensitive electrolytes have emerged as promising alternatives,offering both thermo-reversibility and self-protective properties.However,further research is crucial to fully understand these thermal-shutdown electrolytes.In this study,we propose lower critical solution temperature(LCST)phase behavior poly(benzyl methacrylate)/imidazolium-based ionic liquid mixtures to prepare temperature-sensitive electrolytes that provide reversible thermal shutdown protection of batteries.This electrolyte features an appropriate protection temperature(~105℃)and responds quickly within a 1 min at 105℃,causing cells to hardly discharge as the voltage suddenly drops to 3.38 V,and providing efficient thermal shutdown protection within 30 min.Upon cooling back to room temperature,the battery regains its original performance.Additionally,the electrolyte exhibits excellent cycling stability with the capacity retention of the battery is 91.6%after 500 cycles.This work provides a viable solution for preventing batteries from thermal runaway triggered by overheating.
基金supported by the Beijing Municipal Natural Science Foundation(Grant No.8242014)National Natural Science Foundation of China(Grant Nos.72274123,72004113,72174099,72104123)+2 种基金Henan International Joint Laboratory of Man Machine Environment and Emergency Management,Anyang Institute of Technology(KFKT-001)Key R&D special projects in Henan(221111321000),Interdisciplinary project of University of Science and Technology Beijing(FRF-IDRY-22-017)Science and Technology Commission of Shanghai Municipality(Grant No.24692104600)。
文摘Subway fires often cause significant casualties and property losses.There are some special bidirectional coupling scenarios during subway fires,such as firefighters moving against the evacuation flow to extinguish fires,emergency managers going to the fire scene to respond to emergencies,or other similar scenarios.How to evacuate passengers quickly and enable responders to enter the fire scene has become a big challenge for subway fire evacuation and response.The core goal is to reduce the degree of mutual interaction between these people moving in opposite directions.In this study,the impact of counterflow individuals and proactive avoidance behavior on evacuation processes was investigated through experiments and simulations.The Fire Dynamic Simulator was used to simulate the development of a fire scenario to determine the available safe egress time.Micro-evacuation experiments were conducted to obtain actual evacuation parameters,such as the speeds of different objects.With these parameters as input,a macro subway fire scenario was built to simulate the bidirectional evacuation process.Consistent conclusions were obtained from the experiments and evacuation simulations.The results indicate that the overall evacuation time increases with the number of retrograders.Proactive avoidance behavior can effectively reduce the travel time of counterflow individuals,but it causes slight delays for forward-moving evacuees.An optimization strategy was implemented through conductor guidance.All passengers can successfully evacuate under the optimization strategy,with a 25.3%improvement in overall evacuation time.This research provides some insights into the coordinated evacuation and emergency response during subway fires or similar scenarios.
