Efficient recovery of valuable metals from cathode materials of spent LiCoO2 batteries via co-pyrolysis with cheap carbonaceous materials

Recovery of valuable metals from spent Li-ion batteries has prominent economic and environmental benefits. In this study, a novel approach for recycling valuable metals from spent LiCoO2 batteries via co-pyrolysis with three different carbonaceous materials (waste polyethylene, biomass, and coal)) was proposed and evaluated. The thermodynamic analysis proved that carbonaceous materials (mainly carbon) were theoretically able to facilitate the decomposition process of LiCoO2. The promotion effect on LiCoO2 decomposition was in the following order: coal > biomass > polyethylene, and the decomposition temperature of LiCoO2 could significantly reduce by 400 °C via adding coal. The char produced from the carbonaceous materials, rather than the volatiles, played an important role in LiCoO2 decomposition and reduction. The pyrolysis products of LiCoO2 and coal mixture exhibited typical superparamagnetism and hysteresis behaviours, which benefitted the subsequent magnetic separation. The recovery rates of Co and Li were sensitive to the pyrolysis temperature and residence time, respectively. A high proportion of Co was in the form of CoO below 800 °C and had not been completely reduced, leading to the relatively lower recovery rates of Co below 800 °C. The optimal recovery rates of Co (96.8%) and Li (88.7%) were obtained at the pyrolysis temperature of 800 °C and the residence time of 10 min. The final recovery products were Co and Li2CO3 with rather high crystallinities and purities. Therefore, this study provided a novel approach for the efficient recycling of valuable metals from spent Li-ion batteries with high application prospects.