Recycling battery cathodes to PIN FRs

Minerals recovered from nickel-cobalt-manganese (NCM) batteries were an effective synergist to APP (PIN FR) in TPU (thermoplastic polyurethane). The NCM battery cathode material was prepared by calcination (to remove binders and solvents) and alkaline leaching (to remove the current collector), washed, dried and collected by filtration as a powder. It contained c. 50% nickel, 20% cobalt and 25% manganese (all expressed as oxides not as metals), and traces of fluorine, iron, phosphorus, lithium and copper. It was tested at 0 – 1.5 % loading with 7.5 – 9 % APP (PIN FR ammonium polyphosphate) in TPU elastomer. UL 94 V-0 (3.2 mm) was achieved in all cases (including with 9% APP), compared to Not Rated for neat TPU. LOI and peak heat release rate were improved when NCM material was combined with APP (compared to pure APP), and also mechanical properties were considerably improved. The authors attribute the fire protective effect of the NCM material to increased graphitisation of the char layer generated by APP.

“Flame-retardant thermoplastic polyurethane composites based on ammonium polyphosphate and cathode active material waste”, Z. Gong et al., J. Environmental Chemical Engineering 13 (2025) 116719, DOI: https://doi.org/10.1016/j.jece.2025.116719