18650 Type Lithium Ion Battery Safety Research Of Warehouse Storage

Owing to their excellent features of high power capacity,Light weight,long life cycle,the lithium ion batteries have been widely used in all areas of production and life,such as convenient electronic products,electric vehicles and aircraft.More and more market demand promotes the scale expanding and number increasing of the lithium ion batteries production workshops and warehouses.However,the the lithium ion batteries fires and explosions tend to occur in the store because their thermal stability is sensitive to temperature,extrusion and collision.It not noly causes serious damage to people and device but also hinders to their wide application.To provide theory evidence for the fire safety design of the lithium ion batteries warehouses and data support for the firefighting rescue efficiently and scientifically,this work studies on fire hazards of the lithium ion batteries.The works of this thesis are summarized as following:The influence of states of charge and ambient temperatures on the thermal stability of the lithium ion batteries is analyzed.The mechanism of the lithium ion batteries fire and explosion is also explored.Results show that the increasing of states of charge and ambient temperatures redunces the stability of the lithium ion batteries.Effective control time of the lithium ion batteries fires is 5 min.Early signs for the lithium ion batteries fire are rising surface temperature and a small amount of gas releasing.Melting of separator is critical conditions for the occurrence of the thermal runaway for the lithium ion batteries.The oxygen released by the decomposition of cathode materials reacting with electrolyte is the main reasons of the thermal runaway for the lithium ion batteries.Combustion behavior and fire hazard of the lithium ion batteries under various states of charge have been analyzed.A model is proposed to predict the heat release rates under various states of charge.The lithium ion batteries under various states of charge exhibit repeated jetting fire while being heated.The increase rate of heat release rate and the peak heat release rate rise with the increasing the states of charge,whereas total energy released decreases.Based on the heat release rate experimental data of the lithium ion batteries under different states of charge,t2 correlation has been improved to predict heat release rate of the lithium ion batteries.It not only provides the input parameters for the numerical simulation of lithium-ion battery fires,but also provides a theoretical reference for the analysis of lithium-ion battery fires.Fire behaviors of a lithium ion battery and various lithium ion batteries have been researched.Safety distance of the lithium ion batteries is determineed.Experimental results show that width and height of the flame as well as degree of combustion are proportional to state of charge.Safety distance of the lithium ion batteries is 5 cm determined by both theoretically and experimentally.Finally,the lithium-ion battery fire safety measures during storage are proposed.