Full closed-loop green regeneration and recycling technology for spent ternary lithium batteries: Hydrogen reduction with sulfuric acid cycle -leaching process

With the rapid growth in demand and capacity of lithium-ion batteries (LIBs), a large number of spent LIBs with the dual attributes of hazardous waste and high value-added resources have also experienced a spurt in retirement. In this paper, a process of hydrogen reduction - water-leaching to recover Li - H2SO4 cycle-leaching to recover Ni/Co/Mn to regenerate ternary cathode (NCM) precursor was used to treat mixed spent NCM, and its recovery mechanism was investigated. Under the optimal conditions, Li was completely converted into readilysoluble LiOH by hydrogen reduction and then recovered by water-leaching and CO2 precipitation to regenerate high-purity Li2CO3. While Ni/Co/Mn was reduced to low-valent and could basically be completely leached by H2SO4 and the H2SO4-leaching solution could be cycled to leach Ni/Co/Mn after supplementing with some H2SO4. When the cycle time reached 5, the concentrations of Ni/Co/Mn reached 144.79 g/L, 100.01 g/L, 113.39 g/L, respectively. Finally, a few solids that could not be completely dissolved due to the cycle were leached out by H2SO4 and mixed with the cycle-leaching solution to regenerate the NCM precursor with high-purity and excellent performance for direct commercial application by coprecipitation.