Cobalt and lithium recovery from active mass of spent Li-ion batteries: Theoretical and experimental approach Zita Takacova a, ⁎, Tomas Havlik a , Frantisek Kukurugya b , Dusan Orac a a Technical University of Kosice, Faculty of Metallurgy, Institute of Recycling Technologies, Letna 9, 042 00 Kosice, Slovakia b Flemish Institute for Technological Research (VITO), Unit Sustainable Materials Management, Boeretang 200, 2400 Mol, Belgium abstract article info Article history: Received 16 September 2015 Received in revised form 1 March 2016 Accepted 16 March 2016 Available online 19 March 2016 The paper is focused on the experimental study of cobalt and lithium recovery from active mass of spent lithium batteries with theoretical explanation of behavior of components in this process. Two leaching agents — H 2 SO 4 and HCl were used in order to compare their effects on cobalt and lithium extraction. It follows from the results that using HCl as a leaching reagent is more appropriate than using H 2 SO 4 . Optimal conditions for cobalt and lith- ium recovery were: 2 M HCl, 60–80 °C, leaching time 90 min. The work also explains the influence of temperature on cobalt and lithium extraction from active mass by activation energy in case of both leaching agents. It was found that the cobalt extraction in sulfuric acid occurs in two time periods. In the first time period, in 15 to 20 min from the beginning of leaching, the process is controlled by the rate of a chemical reaction (Ea(Co) = 43–48 kJ·mol -1 ). In second time period, the process changes to diffusion controlled, as it is evidenced from the value of Ea(Co) = 3–3.5 kJ·mol -1 . In the case of HCl, cobalt extraction in first time period is controlled by the rate of chemical reaction, Ea(Co) = 40–44 kJ·mol -1 . In the second time period, process is converted to a mixed mechanism, Ea(Co) = 20–26 kJ·mol -1 . Lithium extraction is controlled by the diffusion in both of time periods, or occurs in mixed mode. Ea(Li) is between 2 and 20 kJ·mol -1 in both of leaching agent. The study of the fine structure confirmed the hypothesis that on the cobalt and lithium extraction affects the internal structure of the active mass, which consists primarily of LiCoO 2 and the cobalt extraction is dependent on lithium extrac- tion from the LiCoO 2 structure. © 2015 Elsevier B.V. All rights reserved. Keywords: Spent Li-ion batteries (spent LiBs) Active mass Hydrometallurgy Leaching Kinetics Recycling 1. Introduction Currently, the lithium ion batteries (LiBs) represent a mobile source of electricity in many electrical devices. Their consumption is constantly increasing because of the expansion of information technologies as well as hybrid and electric vehicles (HEV and EV). It can be concluded that in- creasing consumption of lithium cells will result in long-term increasing amount of LiBs in waste. From that reason, their successful recycling is highly actual issue. LiBs belong to secondary electrochemical cells as a chemical reaction inside of LiBs is reversible. They consist of package, electrodes — anode and cathode, electrode active material, electrolyte and separator. Vari- ous binders and other additives can be added in order to improve their required properties. A special kind of LiBs is polymer LiBs, which differ from conventional LiBs by used separator and electrolyte (Wakihara, 2011; Linden and Reddy, 2001). A cathode active material of LiBs is mainly composed of metal oxides based on LiMO 2 , where M = Co, Mn, Ni etc., which are deposited on an aluminum foil. The most common cathode material is LiCoO 2 (Antolini, 2004). Lithium content in LiBs is in range of 2–5%. Cobalt content in LiBs is up 20% (Miskufova et al., 2009). A cathode active material is a part of active mass which can be ob- tained by mechanical pre-treatment using crushing, grinding, sieving, etc. The active mass is a powder mixture of the cathode and anode ac- tive material (graphite, carbon) and electrolyte (organic solvent with dissolved lithium salts) usually with a particle size 0.8–0.1 mm. The ac- tive mass can be contaminated by residues of the electrode foils and separators, which cannot be mechanically separated. From this reason, the active mass is a mixture of several components — metal, non- metal and metal bearing which have different behavior during leaching. The possibilities of the cobalt and lithium recovery from active mass can be divided into pyrometallurgical and hydrometallurgical treat- ment. Current research in laboratory scale focuses mainly on the sophis- ticated hydrometallurgical processing. It involves leaching of spent LiBs active mass and subsequent extraction of metals from leach liquor. Research on the leaching of the active mass of spent LiBs focuses on selecting a suitable leaching agent, temperature, L:S ratio and other pa- rameters. The leaching is mostly carried out in an acidic leaching agent such as HCl, H 2 SO 4 , HNO 3 (Chen et al., 2011; Kang et al., 2010a, Lee and Rhee, 2003; Paulino et al., 2008; Shin et al., 2005; Meshram et al., 2014, 2015a). The most common leaching agent is H 2 SO 4 at various Hydrometallurgy 163 (2016) 9–17 ⁎ Corresponding author. E-mail address: zita.takacova@tuke.sk (Z. Takacova). http://dx.doi.org/10.1016/j.hydromet.2016.03.007 0304-386X/© 2015 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Hydrometallurgy journal homepage: www.elsevier.com/locate/hydromet