A closed-loop process for recycling LiNi 1/3 Co 1/3 Mn 1/3 O 2 from the cathode scraps of lithium-ion batteries: Process optimization and kinetics analysis Xihua Zhang a,b,c , Hongbin Cao a,b , Yongbing Xie a,d,⇑ , Pengge Ning a,d , Huijiao An a , Haixia You b , Faheem Nawaz c a Beijing Engineering Research Center of Process Pollution Control, Beijing 100190, China b National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing 100190, China c University of Chinese Academy of Sciences, Beijing 100049, China d Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China article info Article history: Received 16 January 2015 Received in revised form 28 June 2015 Accepted 2 July 2015 Available online 3 July 2015 Keywords: Lithium-ion battery Cathode scrap Trichloroacetic acid Leaching kinetics Avrami equation abstract A closed-loop process for recycling LiNi 1/3 Co 1/3 Mn 1/3 O 2 from the cathode scraps for lithium-ion batteries (LIBs) is preliminarily established in this research. Biodegradable trichloroacetic acid (TCA) with hydro- gen peroxide (H 2 O 2 ) is innovatively developed to dissolve LiNi 1/3 Co 1/3 Mn 1/3 O 2 from the cathode scraps. Operational parameters are optimized to obtain a lower Al dissolution rate, but not at the expense of sac- rificing other metals. Under the optimal leaching condition of 3.0 M TCA, 4 vol.% H 2 O 2 , a solid to liquid (S/L) ratio of 50 g/L at 60 °C for 30 min, the leaching rates of Ni, Co, Mn and Li are 93.0%, 91.8%, 89.8% and 99.7%, respectively. In this optimum condition, only 7.0% of Al is leached, and this could be further controlled according to the subsequent utilization of the leachate. Avrami equation is introduced to describe the leaching kinetics of LiNi 1/3 Co 1/3 Mn 1/3 O 2 from the cathode scraps. The apparent activation energies for leaching of Ni, Co, Mn and Li are determined as 44.51, 44.79, 43.81 and 28.00 kJ/mol, respec- tively, indicating that the surface chemical reaction is the rate-controlling step during this leaching process. Ó 2015 Elsevier B.V. All rights reserved. 1. Introduction The production and demand of lithium-ion batteries (LIBs) have significantly increased due to the wide applications in communica- tion, consumer electronics, transportation, power grid and portable appliances [1–3]. The annual production of LIBs increased by 800% throughout the world from 2000 to 2010 [2], which would be fur- ther stimulated by the development of electric vehicles (EVs) and hybrid electric vehicles (HEVs) [2,3]. Large quantities of spent LIBs along with scraps will be generated due to their limited life spans and rapid updating of electronic products. Moreover, the metals, especially the toxic heavy metals, contained in these spent LIBs may cause serious environmental problems, such as soil and underground water contamination, which might affect the health of human beings and animals [4,5]. A substantial number of critical metals, such as Co and Li [6], are also contained in these wastes. Therefore, by recycling metals from these wastes, not only the risks to environmental and public health could be avoided, but also the shortage of some metals used as the raw materials during the pro- duction of LIBs could be fulfilled. Previous reviews [2,3,7] indicated that hydrometallurgical pro- cesses were preferred in metal recycling due to the complete recovery of metals with higher purity, lower energy consumption [8] and lower gas emission [9]. In these processes, LiCoO 2 -based cathode materials are mainly focused, but studies on other cathode chemistries such as LiMn 2 O 4 , LiNi x Co 1x O 2 and LiNi x Co y Mn 1xy O 2 were scarce. Acidic leaching plays an important role in these pro- cesses, thus a substantial number of the reported leaching pro- cesses [10–14] mostly concentrate on extracting as many metal values as possible or even complete recovery from spent LIBs by optimizing the leaching parameters. However, these processes sel- dom dealt with the treatment and utilization of the obtained lea- chate. In order to separate the cathode materials from other materials (Fe, Al, Cu and plastics), various pretreatment proce- dures, including mechanical methods [10–18], thermal methods [10–13,18,19], selective precipitation [20], N-methylpyrrolidone (NMP) dissolution [10–13,18], vacuum pyrolysis [14] and http://dx.doi.org/10.1016/j.seppur.2015.07.003 1383-5866/Ó 2015 Elsevier B.V. All rights reserved. ⇑ Corresponding author at: Institute of Process Engineering, Chinese Academy of Sciences, No. 1 North 2nd Street of Zhongguancun, Haidian District, Beijing 100190, China. E-mail address: ybxie@ipe.ac.cn (Y. Xie). Separation and Purification Technology 150 (2015) 186–195 Contents lists available at ScienceDirect Separation and Purification Technology journal homepage: www.elsevier.com/locate/seppur