Abstract: This work experimentally studied the risk of the gas deflagration and the fire caused by the Lithium- ion battery in case that the thermal runaway happens in an energy storage system. Besides, the risk of the electrolyte under high temperature and the thermal runaway properties of the Lithium ion battery are also investigated. The results indicate that the gases caused by the thermal runaway of the lithium- ion battery performs a high deflagration level, and the lower explosive limit is about 6.1% . The maximum explosive pressure reaches to 0.61~0.76 MPa, which can cause severe damage to the building structure. Besides, the minimum ignition energy of the gases caused by the thermal runaway of the Lithium ion battery is only 0.3 mJ. The releasing gases of the electrolyte under 120~130 ℃ have a lower explosive limit of 2.3%, showing a high risk, which can also lead secondary damage to the human. It is shown that the activation temperature of the thermal runaway of the Lithiumion is between 125~150 ℃ . The experimental results can provide guidance for the detection of the flammable gases and the design of the ventilation system in energy storage system.

Key words: Lithium- ion battery, thermal runaway, flammable gases, deflagration