Direct Production of Ni–Co–Mn Mixtures for Cathode Precursors from Cobalt-Rich Lithium-Ion Battery Leachates by Solvent Extraction

Abstract

A novel solvent extraction scheme was developed for the processing of Co-rich lithium-ion battery (LIB) leachate to a Ni–Co–Mn (NCM) sulfate mixture that can be directly used in the precursor synthesis of LIB cathodes. Conventional hydrometallurgical recycling of spent LIBs usually aims at separation of Li, Ni, Co, and Mn into pure fractions, which is simplified here. Operating pH and the number of extraction stages for each separation were evaluated from batch equilibrium experiments. Two continuous countercurrent extractions with bis(2-ethylhexyl) hydrogen phosphate (D2EHPA) and one with Cyanex 272 were studied in bench-scale mixer-settler equipment, and a Ni–Co–Mn solution with n(Ni):n(Co) = 14.16 and n(Ni):n(Mn) = 8.06 was obtained. The Ni:Co:Mn molar ratio in the NCM mixture can be adjusted to, for example, 8:1:1 using a Co-rich raffinate from the same process, and no additional transition metal salts are required for tuning the composition. Stripping raffinate containing 102.7 g L−1 Co at 99.8% relative purity was obtained from Cyanex 272 extraction. The main benefit of the process concept is that the solvent extraction separations can be operated with less stringent requirements than when producing pure metal salts.

Low-carbon footprint diluents in solvent extraction for lithium-ion battery recycling

“…Table 2 shows the composition of the aqueous solution representative of a leaching solution produced by dissolving NMC cathode materials with sulfuric acid in the presence of hydrogen peroxide. 41 …”

Closed-loop recycling of lithium iron phosphate cathodic powders via citric acid leaching

“…However, the main bottleneck related to LFP batteries recycling is that the economic trade-off between potential revenues and recycling costs is unfavorable at fullscale (Mahandra and Ghahreman 2021). Up-to-date recycling Responsible Editor: George Z. Kyzas technologies prioritize recovery of the most economically valuable elements, as Cobalt, Manganese and Nickel (Chan et al 2021;Jantunen et al 2022;Schiavi et al 2021), while Lithium and Phosphorous have lower market value.…”