Selective cobalt and nickel electrodeposition for lithium-ion battery recycling through integrated electrolyte and interface control

Abstract

Molecularly-selective metal separations are key to sustainable recycling of Li-ion battery electrodes. However, metals with close reduction potentials present a fundamental challenge for selective electrodeposition, especially for critical elements such as cobalt and nickel. Here, we demonstrate the synergistic combination of electrolyte control and interfacial design to achieve molecular selectivity for cobalt and nickel during potential-dependent electrodeposition. Concentrated chloride allows for the speciation control via distinct formation of anionic cobalt chloride complex (CoCl42-), while maintaining nickel in the cationic form ([Ni(H2O)5Cl]+). Furthermore, functionalizing electrodes with a positively charged polyelectrolyte (i.e., poly(diallyldimethylammonium) chloride) changes the mobility of CoCl42- by electrostatic stabilization, which tunes cobalt selectivity depending on the polyelectrolyte loading. This strategy is applied for the multicomponent metal recovery from commercially-sourced lithium nickel manganese cobalt oxide electrodes. We report a final purity of 96.4 ± 3.1% and 94.1 ± 2.3% for cobalt and nickel, respectively. Based on a technoeconomic analysis, we identify the limiting costs arising from the background electrolyte, and provide a promising outlook of selective electrodeposition as an efficient separation approach for battery recycling.

Effect of Thermal Treatment on Nickel‐Cobalt Electrocatalysts for Glycerol Oxidation

“…Considering that cobalt cations may have a higher water coordination number than nickel cations, cobalt can reach the inner Helmholtz layer more easily than nickel cations. Indeed, it has been reported that CoOH + /Co(OH) 2 have higher adsorption tendency as compared to NiOH + /Ni(OH) 2 , being one of the plausible mechanisms of the anomalous deposition [18] …”

“…Indeed, it has been reported that CoOH + / Co(OH) 2 have higher adsorption tendency as compared to NiOH + /Ni(OH) 2 , being one of the plausible mechanisms of the anomalous deposition. [18] XPS analysis was performed to corroborate the chemical structure of the materials. As shown in Figure S4, the Ni 2p spectrum presents a doublet at 873.5 eV (2p 1/2 ) and 855.8 eV (2p 3/2 ) with two satellite peaks, accounting for the presence of Ni(II).…”

Prospects for managing end‐of‐life lithium‐ion batteries: Present and future

“…[26][27][28][29] After mechanical pretreatment, a combination of acids, bases, and reducing agents is usually adopted to dissolve the cathode materials, followed by subsequent purification and separation of the metals through precipitation, solvent extraction, and electrochemical routes. [30][31][32] The hydrometallurgical process can maintain the high purity of the obtained material, and the low temperature operating also highlights the preponderance of safe recovery. Compared with the pyrometallurgical process, energy consumption and gas emissions have dropped a lot.…”

“…The combination of choline chloride and oxalic acid provides a good idea for the separation of cobalt and nickel, given the problems of their separation since ancient times. In addition, Kim et al [ 30 ] found that the deposition potentials of cobalt and nickel in concentrated chlorine electrolytes are totally discrepant from the ordinary dilute electrolyte. Supplemented by the electrode interface design, the efficient separation of cobalt and nickel is easily accomplished by electrolysis, which is also caused by the disparate coordination environments.…”

Cathode electrolysis for the comprehensive recycling of spent lithium-ion batteries

“…Recycling end-of-life lithium-ion batteries (LIBs) becomes a central focus to sustain the battery supply chain because of the ever-increasing LIB market and scarcity of strategic resources such as lithium, cobalt, nickel, etc. [1][2][3][4][5] To mitigate the implications of resource shortage and environmental pollution, state-of-the-art recycling technologies have been intensively researched, [6][7][8][9][10][11][12] such as pyrometallurgy [13][14][15] and hydrometallurgy. [16][17][18] The pyrometallurgical route customarily converts spent lithium transition metal oxide into transition metals/alloys and lithium slags, which faces the challenge of efficiently recycling Li and losing conductive carbon and the PVDF binder.…”