Selective Extraction of Cobalt and Lithium Phosphates from Spent LiCoO2 Cathode Cells: A TRL-4 Study on Process, Kinetics, and Techno-Economics

Lithium cobalt oxide (LiCoO₂) cathodes, comprising 70% of global cobalt and over 1/4th of lithium production, are crucial for recycling to support a sustainable circular economy for critical metals. This study presents an industry-oriented recycling process at technology readiness level-4, involving phosphoric acid leaching of LiCoO₂ cathodes. The process was optimized by using response surface methodology with a central composite design, examining five factors at three levels. The parameters, temperature, and concentrations of H₃PO₄ and H₂O₂ were identified as key factors influencing the selective leaching of lithium and precipitating >99% cobalt as Co₃(PO₄)₂. The activation energy for lithium dissolution suggests that the leaching process follows an intermediate-controlled mechanism. Lithium was subsequently recovered as Li₃PO₄ by adding a 10% stoichiometric excess of Na₃PO₄ and adjusting the filtrate pH to above 12. The profitability of the recycling process is demonstrated by a 39.6% return on investment and a 9.7% internal rate of return.