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Safety

Li-ion Thermal Stability

Aging temperature impact on thermal stability of lithium-ion batteries Researchers cycled commercial pouch cells (NCM622+LMO||graphite) at different temperatures. Cells at 25 °C and 40 °C showed slower capacity loss, but 40 °C experienced faster decay due to SEI overgrowth. At 60 °C, capacity decayed after 30 cycles, attributed to repeated SEI regeneration. Cells at 80 °C rapidly lost capacity after 7 cycles due to SEI growth. Post-ARC test, cells at 25 °C released the most heat, indicating significant aging. Aluminum beads in wreckage at 25 °C and 40 °C suggested internal temperatures exceeded aluminum's melting point. The 80 °C cell had intact aluminum due to film rupture and electrolyte evaporation, reducing heat release. The study provides insights into temperature-dependent effects on pouch cell performance and safety.

The transformation of SEI layer decomposition products at high temperature is the main reason for the difference in electrical performance and thermal runaway behavior due to the cycling of LIBs at high temperatures.

Academia | P. 236 Source: Gao T., Bai J., Ouyang D., Wang Z., Bai W., Mao N., & Zhu Y.

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