Upgrading spent battery separator into syngas and hydrocarbons through CO2-Assisted thermochemical platform

Abstract To diminish the use of fossil fuels, there have been amplified technical developments of rechargeable batteries. With increasing demand of the secondary batteries, the recovery of useful materials from waste battery becomes significant. In this study, pyrolysis of battery separator in the lithium-ion battery was studied to fundamentally understand the thermal degradation of volatile compounds in the batteries and to recover hydrocarbons and syngas (H2/CO). To make this practice more environmentally sound, CO2 was used as a co-reactant. Pyrolysis under inert atmosphere (N2) was studied as a reference. Prior to battery separator pyrolysis, the composition of the separator (tri-layer of PP/PE/PP) and its thermolytic profile were confirmed. Single-stage pyrolysis converted the separator into aliphatic liquid hydrocarbons, while double-stage pyrolysis produced benzene derivatives, H2 and C1-2 hydrocarbons under both N2/CO2 environments. To further convert hydrocarbons into H2, NCM (lithium nickel cobalt manganese oxide) cathode, one of widely used Li-ion battery cathodes, was used as a catalyst. In the presence of NCM catalyst, H2 production increased 25 times higher. In CO2 condition, catalytic pyrolysis resulted in remarkable CO formation through the homogeneous gas phase reactions between CO2 and gas phase volatile hydrocarbons degraded from thermolysis of battery separator.