Theoretical and experimental analysis of the lithium-ion battery thermal runaway process based on the internal combustion engine combustion theory

This paper presents a theoretical and experimental analysis of the thermal runaway process of lithium-ion batteries (LIBs) based on the internal combustion engines (ICEs) combustion theory. The experiments used 3.7 V, 31.6 Ah, lithium nickel cobalt manganese oxide cells and an electronically pilot-ignited natural gas engine. The temperature characteristics between the ICE combustion process and the LIB thermal runaway process were analyzed and compared. The process evolution of the LIB failure process was summaried with the ICE working .process. One key evaluation parameters (T-sa) and its physical meanings of LIB thermal runaway characteristics was proposed. The reaction mode of the LIB thermal runaway process and its process divisions were analyzed based on the ICE combustion theory. In addition, the method of optimizating the LIB thermal runaway process was pointed out from the viewpoint of reaction mode. The results show that there exist high similarities between the temperature characteristics of the ICE combustion process and the LIB thermal runaway process. The temperatures of the above two processes first rise slowly, then rise sharply, and finally fall rapidly. The LIB failure process can be divided into four processes similar to those of the ICE working process: assemble, abuse, thermal runaway, and eruption. T-sa is the key parameter for early warning and evaluation of thermal runaway. The whole process is dominated by reactivity-controlled self-accelerated chemical reaction (RSCR) mode. The LIB RSCR can be characterized in terms of the induction period and duration, similar to the ICE combustion process. The duration is divided into the slow-reaction, fast-reaction and post-reaction periods. The reaction process is always accompanied by derivative processes, such as gassing, erupting and burning. Based on the ICE combustion theory, it can be concluded that the main reason for the un-controlled LIB thermal runaway process is that the internal cell boundaries are not controlled effectively.