Process design and economic analysis of hydrogen roasting integrated with CCU for a carbon-free spent LIB recycling process

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In the lithium-ion battery (LIB) recycling process, the roasting step decomposes the complex cathode material into metal oxides before leaching and precipitation. Hydrogen gas is a potential candidate among various roasting agents because of its rapid roasting time and zero CO2 emission. However, additional flue gas emission is unavoidable on the industrial scale to meet the roasting temperature and further crystallization of the produced LiOH slurry. This study proposed and simulated a carbon-free LIB recycling method via an integrating system of hydrogen roasting and CO2 capture and utilization (CCU) composed of the following processes: hydrogen roasting of cathode material; two-way Li extraction; acid leaching; and selective extraction of remaining metal oxide. In the two-way Li extraction, the LiOH slurry was split and converted into LiOH·H2O(s) and Li2CO3(s) via crystallization and the CCU process, respectively. In the CCU process, the slurry was utilized as a wet CO2 absorbent in the flue gas emitted from the roasting and crystallization process. According to sensitivity analysis, 98.10 % Li recovery with zero CO2 emission was accomplished in a split fraction of 0.26. Furthermore, over 99 % recovery of remaining metal resulted from early Li rejection in the metal oxide mixture. Economic analysis was conducted with a 10,000 ton/year recycling capacity, and the net present value of the proposed system is 2.74E + 09 $, 3.08 % higher than the conventional hydrometallurgy system. The proposed system offers higher Li recovery and feasible economic profit with zero CO2 emission and less chemical waste disposal than the conventional system.