Comprehensive recovery of NCM cathode materials for spent lithium-ion batteries by microfluidic device

• The co-extraction performance of Mn-Co-Ni was improved with the mixture of D2EHPA and Cyanex272. • The mechanism of saponification and extraction with the mixed extractant was explained based on IR spectral results. • The comprehensive recovery of Mn-Co-Ni and Li was realized leveraging the microextraction equipment with satisfactory recycling efficiency. With the gradual expansion of the market scale of lithium-ion batteries, the importance of comprehensive recycling of lithium-ion battery cathode materials has become increasingly prominent. In this work, a comprehensive recovery of leachate from spent NCM cathode materials was established with the microextraction equipment. In the process of extraction, we established an economical and efficient co-extraction method of Mn-Co-Ni to separate with Li ions in the leachate. After investigating the extraction effects of single extractant of D2EHPA and Cyanex272, the co-extraction pattern of the mixed extractant was summarized by exploring the correlation of extraction efficiency and selectivity with equilibrium pH, extractant concentration ratio and two-phase ratio. The mechanism of saponification and extraction with the mixed extractant was explained based on the IR spectral results. After separately exploring the stripping process and the deep recovery process of Ni, the metal ion of lithium was recycled via precipitation. The regenerated lithium carbonate reached 99.2% purity with uniform particle size distribution. Leveraging the microextraction equipment with greater mass transfer coefficient, a comprehensive extractive recovery process of Mn-Co-Ni was established and realized with the recovery efficiency of Mn, Co, Ni and Li of 99.9%, 98.6%, 99.5% and 90%, respectively. The regenerated metal solution of Mn-Co-Ni can be further used to prepare the precursors of regenerated cathode materials.