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Material extraction: from black mass to battery-grade materials

15/01/2026

RHINOCEROS project validates extraction routes

The road to a green transition relies heavily on Europe’s capacity to electrify our way out of the use of coal, oil and natural gas before it becomes too late. A large part of this European vision counts on accelerating its transition to electric mobility and therefore upscaling its battery production. With scarce primary resources, EU policy makers push for the recycling of end-of-life [EoL] lithium-ion batteries [LIBs] as a strategic priority. More than recovering the metals trapped in defunct applications, the challenge lies in producing battery-grade materials that can reintegrate the supply chain. The R&I RHINOCEROS project has recently validated its extraction routes at laboratory scale, a preliminary step before pilot-scale implementation.  

Electrochemical recovery of lithium 

Researchers at Chemistry Department of Sapienza University of Rome [UoS] tested various electrochemical parameters to optimise Li extraction from the black masses [BM] obtained by the mechanical pre-treatment operations conducted in work package [WP4]. Their electrochemical process initially demonstrated its ability to extract Li without causing the dissolution of other cathode elements. Later, the research group replicated the electrochemical conditions in a two-chamber cell, where they achieved 82% Li recovery, later refined to produce LiOH with >99.5%. 

Selective electrochemical recovery of Li using a two-chamber cell configuration. © University of Sapienza

Direct synthesis of cathode and anode materials via hydrometallurgical routes

Additional to electrochemical route, UoS also explored a hydrometallurgical route to synthesise Li-Mn-rich cathodes and reduced graphene oxide (rGO) directly from black mass. Applying Hummers’ method, researchers converted graphite into graphene oxide and co-precipitated metals to form Li-Mn-rich precursors. Electrochemical tests indicate that Li-Mn-rich cathodes derived from thermally treated black mass achieved performance comparable to those made from commercial salts, with capacities up to 202 mAh/g. Reduced graphene oxide synthesised from mechanically treated black mass displayed superior performance compared to rGO from commercial graphite.

Solvometallurgical recovery of Ni and Co

After studying the effects of the pre-treatment processes applied in WP4 to generate BM, researchers at TECNALIA [TEC] validated a solvometallurgical process using deep eutectic solvents (DES) to recover nickel and cobalt under mild conditions. The process achieved >95% metal leaching efficiency and precipitation yields purity.

Moreover, researchers have confirmed the scalability of the solvometallurgical process to large-lab testing without performance loss. To address the costs of this process, TEC researchers have also succeeded in demonstrating the reuse of DES up to 12 times across three systems.

Direct recovery of Ni/Co/Mn/Li with gas-diffusion electrocrystallisation

VITO advanced their proprietary gas-diffusion electrocrystallisation [GDEx] to recover Ni, Co, Mn and Li from leachates obtained from black mass and other WP5 partners. The process delivered >90% recovery rates for Ni, Mn and Co and>99% for Li in the form of layered double hydroxide (LDH) and spinel-type nanostructures for the synthesis of cathode active materials.

With better results obtained from the lithiated nickel manganese cobalt oxide (LNMCO) material synthesised from the leached black mass provided by ACC [thermal pre-treatment], VITO researchers validated its electrochemical activity as a cathode material for LIBs by assembling coin-type half cells. The recycled cathode material showed electrochemical activity, but the achieved capacity is lower than the expected which reveals the requirement of the optimisation process of upscaled extraction of metals, lithiation and slurry processing.

Optimised recovery of materials from low concentration waste streams

A different task in the refining work package, led by LEITAT and TEC, aims at the recovery of low concentration materials from leachates and effluent streams produced in previous refining tasks. Researchers have developed polymer inclusion membranes (PIMs, LEITAT) and electrochemical systems (TEC) to recover metals from low-concentration streams, achieving up to 80 % recovery for Co and Mn, up to 60 % for Ni and >70 % lithium precipitation with high carbonate purity (>94 %).

In the case of the polymer inclusion membranes, several experiments were performed to define and select both the adequate extractant and the optimal operational conditions. Additionally, selectivity tests are being conducted with a focus on assessing the selectivity of PIM towards a specific metal. Finally, the selected PIMs were defined as follow:

Lab scale validation of most promising routes

After a multi-criteria assessment considering technical performance, eco-efficiency, and scalability, the TEC solvometallurgical route using ACC thermal black mass was selected for pilot-scale validation. This process demonstrated the best balance of recovery efficiency, cost, and environmental impact, and will serve as the reference flowsheet for WP6 upscaling.

Results evaluation at lab scale and prior to upscaling. ©TECNALIA