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

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. Copyright © 2021 Elsevier Ltd. All rights reserved.