Kinetics, thermodynamics, and product formation during pyrolysis conversion of protection board from spent lithium-ion batteries

Abstract

© 2025 Elsevier LtdThermal treatment of spent lithium-ion batteries offers the benefits of decomposing organic components while concentrating valuable metals. This work investigated the kinetics, thermodynamics, and evolved products during the protection board pyrolysis under N2 and CO2 atmospheres. The degradation process was divided into stages of below 400 °C, 400–700 °C, and 700–900 °C. Peak temperatures at the maximum mass loss rate were observed at 359–399 °C in N₂ and 367–393 °C in CO₂. The primary products evolved from phenolics into ketones and acids, and eventually into alkanes. Brominated products such as bromomethane and 1-bromobutane were also detected, indicating the requirement of debromination to improve the usability of pyrolysis products. The average activation energies were determined to be 218.33 kJ/mol in N₂ and 308.91 kJ/mol in CO₂. D4 and D1 reaction mechanisms were found to best describe the pyrolysis process in two atmospheres. Positive values of ΔH and ΔG indicated the endothermic and non-spontaneous characteristics. The difference between ΔH and Ea values ranged from 5.26 to 7.70 kJ/mol in N₂ and 5.12–7.48 kJ/mol in CO₂, indicating a high possibility of overcoming the potential energy barrier.

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