Dataset: Task-Specific TEAB–Lactic Acid–NH₂OH·HCl Solvent for Selective Co/Li Recovery from LiCoO₂ Black Mass

This dataset tests the hypothesis that a task-specific TEAB–lactic acid–NH₂OH·HCl ternary solvent can be deliberately designed as a structured, redox-active leaching medium for LiCoO₂-derived black mass, rather than selected only by trial-and-error extraction performance. The central idea is that TEAB provides the ionic scaffold, lactic acid provides proton activity and oxygen-donor coordination, and NH₂OH·HCl supplies in situ reductive functionality needed to convert poorly soluble lattice-derived Co(III) into soluble Co(II), thereby enabling efficient and selective recovery of cobalt and lithium.

The data include feed characterization, formulation screening, spectroscopic solvent characterization, viscosity measurements, leaching experiments, cobalt oxidation-state analysis, kinetic fitting, response-surface modeling, product-phase verification, elemental mass balance, and regeneration testing. The black mass was first confirmed to be cobalt-rich by ICP analysis (64.318 ± 0.379 wt.% Co; 5.130 ± 0.025 wt.% Li), after which multiple solvent compositions were prepared and screened through time-resolved liquid formation, UV–Vis baseline behavior, FTIR, Raman, NMR, and rheology. The selected 1:1:1 solvent was then used for leaching under different temperatures, times, and solid loadings. Metal concentrations were measured by ICP-OES using a sampling-corrected cumulative mass-balance approach, cobalt speciation was assessed by matrix-matched UV–Vis, and recovered solids were identified by XRD. Regeneration data were collected across seven recycle runs, including recovery, viscosity, conductivity, make-up demand, and residual solute trends.

The dataset shows that the balanced 1:1:1 TEAB–LA–NH₂OH·HCl formulation gave the best overall compromise between liquid homogeneity, processable viscosity, and chemical functionality. Matrix-matched UV–Vis showed that dissolved cobalt in the leachate was predominantly Co(II) (99.4%) with only 0.6% Co(III), confirming that the solvent behaves as a genuinely reductive medium and not simply an acidic one. Under the most practical operating condition (90 °C, 90 min, 33.3 g L⁻¹), the solvent achieved 97.80 ± 0.14% Li and 99.83 ± 0.03% Co extraction. XRD confirmed downstream recovery of crystalline Li₂CO₃ and CoC₂O₄·2H₂O, while regeneration tests showed sustained cobalt recovery of 99.24–99.87% over seven cycles.

Keywords
LiCoO₂ black mass; lithium-ion battery recycling; deep eutectic solvent; ternary solvent; tetraethylammonium bromide; lactic acid; hydroxylammonium chloride; reductive leaching; cobalt recovery; lithium recovery; response surface methodology; kinetic modeling; solvent regeneration; hydrometallurgy.