This project is prompted by the urgent need for both i) efficient recycling processes of End-of-Life (EoL) batteries, which are becoming more and more abundant in Europe, and ii) production of high performance materials for batteries at competitive cost. Particularly, electrodes active materials, including strategic-critical raw materials such as graphite, cobalt, nickel and manganese, which account for more than 50% of the battery cost, need to be recovered from EU resources and recycled into the batteries manufacturing chain.
Here, a novel recycling route for EoL Li-ion batteries, showing lower processing cost and better environmental impact as compared to the alternative state-of-art processes (i.e. pyro- or hydro-metallurgical) that are currently implemented to separate and recover the batteries metals, particularly, Ni, Co and Mn, will be proposed. The goal is to recover graphite and directly synthesize a high quality NMC cathodic material (Li(NixMnyCoz)O2) for new batteries, without the need to separate the individual metals, which is a costly operation.
The recovered NMC oxide and graphite will be used as cathode and anode active materials, respectively, for new Li-ion batteries. A full physical chemical characterization on these materials will be carried out prior to the battery assembly, to assess their suitability as cell components and tune the recycling process. Indeed, there¿s a critical concern in controlling the purity, particle size, thermal stability and morphology of final products to improve the battery performance. Electrochemical tests on the battery prototypes, assembled by selected recovered materials, will be performed by charge-discharge cycles under current-density regimes of interest for automotive applications. Possible undesired reactivity of the NMC cathode at highly oxidized state will be controlled by tuning the electrolyte composition through the addition of ionic liquid compounds stabilizing the electrode/electrolyte interface.
A major obstacle, to increase the competitiveness of the EU industrial sector in the global batteries demand, is to secure the material resources needed to manufacture Li-ion batteries. These include critical raw materials such as cobalt and graphite, scarcely available as primary resources within the EU area. The recycle of batteries within the EU area is currently regulated by the Directive 2006/66/EC [1]. This fixes a 45% mandatory collection rate and 50% recycling efficiency for Li-ion batteries (LIBs). Through barely attained by member states, these targets are incompatible with the demand of raw materials and the risk of environment contamination. Major obstacles hindering the extensive recovery and application of batteries materials are the elevated costs and/or the negative environmental impact of the currently implemented pyrometallurgical and hydrometallurgical recycling processes [2-4].
Innovative processes increasing the recycling efficiency and reducing the process costs can provide important drivers for change. An effective strategy overcoming these limitations is the intensification of hydrometallurgical processes by the integrated recycling and production of electrodic batteries materials. The main idea is that the different electrodic materials do not need to be separated from any other if they are used to produce new batteries electrodes. In this latter case, the solution obtained by leaching the electrodic powder of spent LIBs can be directly used to ¿resynthesize¿ new batteries electrodes, thus excluding the downstream costly and complex separation of the different metals. The exclusion of the separation stages following leaching can decrease the consumption of energy and reactants and the volume of generated wastes, and increase the recovery yield of the electrodic materials, delivering, at the same time, a high value electrode material that can be employed to produce new LIBs. Different methods have been recently implemented to "resynthesize" cathode and anode materials from the leaching solution generated by the hydrometallurgical treatment of spent LIBs [5]. Such a combined approach is particularly desirable for LiNixMnzCoyO2, that is the cathode material mainly employed for the application in electric vehicles. Indeed, cobalt, nickel and manganese exhibit extremely similar physical-chemical properties and their separation is very tricky [6].
Therefore, ELLIBAT will introduce an innovative hydrometallurgical treatment including the leaching of the powder, the purification of the leaching solution and the crystallization of the mixed transition metal hydroxides.
Validation of the recovered powders, both cathodic NMC oxides and anodic graphites, in LIB prototypes will be among the first valuable attempts closing the battery value chain [7], demonstrating the possibility of realizing sustainable, high-performing battery systems at reduced costs and environmental impact.
[1] https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:02006L0066...
[2] Georgi-Maschler, T.; Friedrich, B.; Weyhe, R.; Heegn, H.; Rutz, M. J. Development of a recycling process for Li-ion batteries. J. Power Sources, 2012, 207, 173-182.
[3] Ellis, B. L.; Lee, K. T.; Nazar, L. F. Positive electrode materials for Li-ion and Li-batteries. Chem. Mater., 2010, 22 (3), 691-714.
[4] Zou, H.; Gratz, E.; Apelian, D.; Wang, Y. A novel method to recycle mixed cathode materials for lithium ion batteries. Green Chemistry, 2013, 15 (5), 1183-1191.
[5] Yao, L.; Yao, H.; Xi, G.; Feng, Y. Recycling and synthesis of LiNi 1/3 Co 1/3 Mn 1/3 O 2 from waste lithium ion batteries using d, l-malic acid. RSC Advances, 2016, 6 (22), 17947-17954.
[6] Sa, Q.; Gratz, E.; He, M.; Lu, W.; Apelian, D.; Wang, Y. J. Synthesis of high performance LiNi1/3Mn1/3Co1/3O2 from lithium ion battery recovery stream. J. Power Sources 2015, 282, 140-145.
[7] Chen, M.; Zheng, Z.; Wang, Q.; Zhang, Y.; Ma, X.; Shen, C.; Xu, D.; Liu, J.; Liu, Y.; Gionet, P. Closed Loop Recycling of Electric Vehicle Batteries to Enable Ultra-high Quality Cathode Powder. Scientific Reports, 2019, 9 (1), 1654.