The experimental investigation of thermal runaway characteristics of lithium battery under different concentrations of heptafluoropropane and air

Abstract

The thermal runaway (TR) of lithium-ion batteries (LIBs) has become a crucial issue in both new energy vehicle systems and energy storage systems. If the heptafluoropropane (HFC-227ea) was used as a blanket gas for delaying the time of LIB TR would be a meaningful work. In this paper, the TR characteristics of cylindrical 18,650 LIBs with various state of charges (SOCs) have been investigated under different HFC-227ea concentrations. The experimental results demonstrate that the temperature, mass loss, and heat release rate are proportional to the SOCs for a given HFC-227ea concentration. The delay effect on the ejection time and combustion time of the TR is much more obvious with the increase in HFC-227ea concentration. The values of surface temperature and total heat release reach their lowest values when the HFC-227ea concentration in the seal box is 100 %, and the effect of HFC-227ea on surface temperature was specifically analyzed. It can be found that the HFC-227ea is used as a protective atmosphere which can prevent the TR effectively.