Influence of Lithium Plating on the Thermal Properties of Automotive High Energy Pouch Batteries

In this study, the effect of lithium plating (LP) on the thermal properties of lithium-ion batteries (LIBs) was investigated. A large-format pouch 64.6 Ah cell with a graphite-SiOx/NMC chemistry was artificially aged (AA_LP) in the laboratory under specific conditions to induce LP on the anode. For thermal behavior analysis, temperature ramp experiments were conducted in a nitrogen-filled steel container on the cycled cell, as well as on fresh and real-life aged cells with the same specifications. Characteristic temperatures, such as first venting and safety critical temperatures, were monitored; additionally, the exhaust gas composition was analyzed using Fourier transform infrared spectroscopy (FTIR) and gas chromatography. It was revealed that the voltage decay of the cells started well before any safety-critical temperature, and the first venting of the AA_LP cell was significantly reduced to 112 °C in comparison to the fresh and real-life aged cells, in which it occurred at 130 °C and 134 °C, respectively. The earlier venting of the AA_LP cell was attributed to the reaction of the plated metallic lithium and the electrolyte. The safety-critical temperature rate (>10 °C/min) occurred at 160.9 °C for AA_LP and at around 159.1 °C for the fresh and real-life aged cells. The maximum temperatures reached were 616 °C, 553 °C, and 566 °C for the fresh, real-life aged, and AA_LP cells, respectively. No significant difference was observed in the exhaust gas after the thermal runaway for the tested cells.