Cheng Yang

Lithium recovery from spent LiFePO4 batteries is significant to prevent resource depletion and environmental pollution. In this study, the employment of “water in salt” electrolyte in LiFePO4 battery enlightened us to develop a novel method for the selective recovery of lithium from spent LiFePO4 batteries through oxidizing LiFePO4 to FePO4 with sodium persulfate (Na2S2O8). Effect of several variables on the Li leaching efficiency was investigated. Additionally, combined thermodynamic analysis and characterization of XRD, XPS were employed to investigate the leaching mechanism. More than 99% of Li can be selectively leached in 20 min at ambient temperature with only 0.05 times excess of Na2S2O8. The high leaching efficiency can be ascribed to the stability and without destruction for the solid structure during the oxidation leaching. A closed-loop process was then proposed for recycling entire spent LiFePO4 batteries, and finally high purity Li2CO3 (99 wt %) was successfully prepared. The process is economically feasible and environmentally friendly and has great potential for the industrial-scale recycling of spent LiFePO4 batteries.

Additive Manufacturing (AM) technology has the potential to significantly improve supply chain dynamics. The purpose of this paper is to investigate the impact of AM on spare parts supply chain. Three supply chain scenarios are investigated in this paper, namely conventional supply chain, centralised AM-based supply chain and distributed AM-based supply chain. Based on system dynamics simulations, this paper specifically compares three supply chain scenarios, in terms of total variable cost and carbon emission. The results show the spare part supply chain utilising AM is indeed superior to the traditional one in sustainable performance. It is also expected that AM can facilitate the spare parts supply chain to achieve more economic benefits along with its development. To our knowledge, this paper is one of the early studies that explores the impact of AM on supply chain performance and quantitatively examines the superiority of utilising AM in spare parts supply chain. Some suggestions are also provided to help managers adopting AM in their spare parts supply chains.

The wet chemical processes of LiFePO4, hydrothermal synthesis and hydrometallurgical recovery, are of great importance during the life cycle of LiFePO4. To analyze these two processes, E-pH diagrams for the Li-Fe-P-H2O system are plotted from 298 to 473 K in this study. The E-pH diagrams can well explain the practical operating conditions of hydrothermal synthesis and hydrometallurgical recovery and provide thermodynamic basis for them. Besides, suitable conditions for the hydrothermal synthesis of LiFePO4 are obtained from the E-pH diagrams, including high temperature, low redox potential, optimum pH 7.8–8.4, and excess stoichiometric lithium. As found in the E-pH diagrams, LiFePO4 will change to ferric phosphate by promoting the redox potential, while lithium will be extracted to the aqueous solution. Based on the above results, a method is proposed for the selective leaching of lithium from spent LiFePO4, which is successfully verified by leaching experiments. At room temperature (298 K), neutral pH (7.0), and low liquid–solid ratio (5:1), 95.4% of lithium can be extracted using 2.7 M H2O2 as the oxidant, while iron remains in the residue. This method shows a promising commercial value as it can realize the selective extraction of valuable lithium from spent LiFePO4 and avoid using large amounts of acid and alkaline.

Lithium recovery from spent lithium-ion batteries (LIBs) becomes increasingly important due to the shortage of lithium resources. The difference in the stability for metal sulfates enlightened us to preferentially extract lithium from spent Ni–Co–Mn ternary (NCM) material through selective sulfation and simple water leaching. The effect of important variables on the metals’ leaching efficiency was systematically investigated. Additionally, combined thermodynamic analysis and characterizations were used to investigate the conversion mechanism in the sulfation roasting process. After roasting with (NH4)2SO4 at 650 °C, LiNixCoyMnzO2 is completely decomposed and converted into Li2SO4, NiO, Co3O4, and LiMn2O4. Over 90% of lithium can be selectively water leached at ambient temperature in only 0.5 h, and then battery-grade Li2CO3 (purity>99.90%) can be successfully prepared without prior concentration and purification processes. Furthermore, sulfation roasting also promotes the extraction of Co and Ni in the following acid leaching process. Finally, a closed-loop and green process was presented for recycling spent NCM materials. Our work represents an environmentally friendly and economically feasible approach, which has great prospect for the industrial-scale recycling of spent LIBs. The finding may also have general implications in the recycling of multiple metals containing hazardous materials.