Sustainable utilization of low-value lithium-ion battery wastes in cement and concrete

Spent LiFePO4 batteries will surge soon due to the global trend towards adopting electric vehicles. The recycling of the batteries leaves low value FePO4 dominated waste (FPW), which is currently not efficiently repurposed. This study aims to reveal the characteristics of FPW, investigate its effects on cement hydration, and explore potential applications in the concrete industry. FPW was used to replace cement at increased ratios up to 10%. The results showed that a suitable dosage of the battery waste (e.g. 5%) enabled the blended cement binder to achieve refined pore structure and enhanced 7- and 28-day compressive strength. FePO4 reacted in cement binder which consumes crystal CH and generates amorphous hydroxyapatite, potentially leading to microstructure refinement. Additionally, FPW exhibited the potential to be developed as a concrete retarder. Continuous retarding on cement hydration was observed, primarily for C3S and C3A at an early age of 1 day, and turned to C2S and C4AF thereafter.