Abstract: this paper introduces a case of fire accident in a lithium-ion battery factory. The cause of the fire was accurately identified through video analysis, on-site investigation, investigation and inquiry, and physical evidence detection. A professional analysis of the lithium-ion battery products provided by the manufacturer using non-destructive and destructive testing determined that the product quality problems of the polymer lithium battery in the activation room were the direct cause of the accident, the internal short circuit of polymer lithium battery leads to the rupture of the battery shell, which leads to spontaneous combustion. The study can provide reference for similar fire investigation, at the same time, fire prevention measures and safety management measures for lithium-ion battery production plants are proposed.

Key words: activation room, fire investigation, lithium-ion battery fire accident, lithium-ion battery factory