![]() Because the lithium ion battery contain considerable active electrodes and flammable electrolyte, thus heat is generated in the cell under abnormal conditions such as over-charging or internal short circuit, which can result in dangerous thermal runaway reactions in the worst case 3, 4, 5. Electric energy and chemical energy convert by each other during charge and discharge, which escape the limitation of Carnot cycle in second law of thermodynamics to get higher energy conversion efficiency than heat engine 2. It transports Li + from one electrode material to another to reserve and provide electric energy. Lithium ion battery (LIB) is widely used in various electronic equipment, electric vehicles and energy storage 1. It is analyzed that the internal short and the Li + distribution are the main causes that lead to the difference. The results indicate that the battery fire hazard increases with the SOC. But the heating time and combustion time become shorter with the ascending of SOC. The critical temperatures of ignition are at 112–121☌ on anode tab and 139 to 147☌ on upper surface for all cells. The reason is that a phase change occurs in Li(Ni xCo yMn z)O 2 material from layer structure to spinel structure. ![]() Based on the phenomenon, the combustion process is divided into three basic stages, even more complicated at higher SOC with sudden smoke flow ejected. The mass loss rate, temperature and heat release rate are used to analyze the combustion behavior in reaction way deeply. The flame size variation is depicted to analyze the combustion behavior directly. To investigate the combustion behavior of large scale lithium battery, three 50 Ah Li(Ni xCo yMn z)O 2/Li 4Ti 5O 12 batteries under different state of charge (SOC) were heated to fire. However, the knowledge on the battery combustion behavior is limited. Safety problem is always a big obstacle for lithium battery marching to large scale application.
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