Abstract: In recent years, lithium-ion battery fire accidents have occurred frequently, and the consequences of fire accidents are also extremely serious. Developing high-efficiency fire extinguishing agents for lithium-ion batteries has become one of the research hotspots. In this paper, a kind of cellulose based flame-retardant hydrogel was synthesized by using polymer materials, crosslinking agent and flame retardant, and mixed with water in proportion to form a hydrogel fire extinguishing agent. The fire extinguishing experiment shows that, compared with pure water mist, this kind of hydrogel extinguishing agent can reduce the surface temperature of the battery more quickly and put out the open fire. At high temperature, it can cover the battery surface, play a role of continuous cooling, and effectively reduce the height of the second temperature peak. Moreover, the addition of flame retardants can further increase the cooling rate, which has a good fire extinguishing effect on lithium iron phosphate batteries and can be used for emergency fire extinguishing of lithium-ion batteries.

Key words: storage battery state of health, least squares support vector machine, residual connection, gated cyclic unit, two-level anomaly diagnosis