In-situ selective extracting lithium from waste LiFePO4 cathode by gas–solid oxidative deintercalation

Abstract

The surging number of waste lithium-ion batteries has brought great challenges to the recycling industry, and the efficient and low-cost extraction of valuable components in waste lithium-ion batteries is meaningful. In this study, a gas–solid oxidative deintercalation method is proposed to efficiently extract lithium from spent lithium iron phosphate (LFP) batteries. Specifically, chlorine was utilized to oxidize Fe(II) in the LFP to Fe(III), thereby resulting in the release of lithium ions from the LFP lattice. Sequentially, the deintercalation lithium ions react with in-situ chloride ions to form lithium chloride that is easily extracted by water leaching. The results show that the gas–solid oxidative deintercalation accompanies strong exotherm, which can occur rapidly at normal temperature. After oxidative deintercalation (25 °C for 20 min) – water leaching (30 °C for 30 min), the leaching efficiency of lithium was 98.57 %, while the leaching efficiencies of iron, phosphorus, and aluminium were less than 1.5 %. Meanwhile, the main component in the leaching residue is FePO₄ with stable crystal structure, which can be used for the re-generation of LFP batteries. The regenerated LFP cathode material demonstrates a spherical morphology, with an initial discharge capacity of 153.34 mAh g⁻¹ at 0.1 C. Compared with the traditional lithium recycling process, this novel process presents remarkable advantages in production cost and efficiency. Overall, these findings provide a new insight for the recycling of waste lithium-ion batteries.