XRD patterns of the MC processed cathode waste materials with Al and Ca as reducing agents
The European energy transition will be built on electrification, relying on clean technologies highly depending on metals, the majority being listed as critical and strategic raw materials. JRC’s Foresight Study, assessing supply chain dependencies and predicting materials demand until 2050, highlights EU’s need to diversity and secure a more resilient resourcing of needed metals. Additional recommendations refer to the necessity to explore Europe’s potential to build internal capacities for mining, refining and processing materials needed for battery production.
In the coming years, demand for lithium-ion batteries (LIBs) will be driven by the automotive sector, complemented by the demand for energy storage systems (ESS) storage requested by the deployment of renewables. Compared to the current supply of materials, major increases are foreseen for graphite (45% in 2030 and 85% in 2050) and lithium (Li) (100% in 2030, expected to reach 170% in 2050). In 2030, the cobalt (Co) demand for batteries will represent almost 60% of the current world supply, expecting to decrease to 40% in 2050, partly due to the shift towards more nickel-rich batteries [source: Foresight Study, JRC].
In the current scenario, overshadowed by geopolitical instability and reliance on powerful nations for critical minerals, the recently adopted Critical Raw Materials Act (CRMA) underpins, among other solutions, the need to turn towards domestically sourced recycled metal, which will help reduce reliance on imports or single sources. With clear objectives to strengthen EU’s capacities along the entire value chain, the CRMA additionally sets a threshold for the EU’s processing capacity, which should cover by 2030 at least 40% of the domestic annual consumption of strategic materials.
Researchers from SINTEF have been studying the possibility of recovering Li, nickel (Ni) and Co from secondary raw materials such as black mass, as well as Li from primary resources – spodumene concentrate. The team at SINTEF approached the task by converting the metals in raw materials using molten salt chlorination, a process that could become an alternative to state-of-the-art (SoA) hydrometallurgy.
Researchers conducted experiments on three types of input materials: one spodumene concentrate and two different samples of black mass (BM), the first one of unknown battery chemistry and pre-treatment, while the second BM sample, recovered from an NMC material, had undergone pyrolysis pre-treatment.
The experiments allowed researchers to study the thermal expansion and melting behaviour of the spodumene concentrate, obtaining the highest Li yield (100 %) when chlorine gas is used in a mixture of calcium chloride, sodium chloride and potassium chloride at a temperature of 727 ⁰C . Experiments on black mass material showed the highest chlorination yields were obtained from uncalcined material (Li 64 %, Co and Ni 22-24 %, Cu 83% and Mn 49 %) in a mixture of lithium chloride and potassium chloride at at 470 ⁰C.
The results of this research was presented by SINTEF representatives at the Joint Symposium on Molten Salts in November 2023.
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© visual: SINTEF
Using alkaline leaching process on spodumene concentrate, the maximum extraction of Li achieved thus far reached 75%. The leachate transformation, even after the filtration step, hinders the sample analysis and further processing. To overcome this challenge, upcoming experiments will explore elevated temperatures, diverse additives, and further investigate the chemical precipitation process.
During the advanced solvometallurgy applied on spodumene concentrate, the research team at TECNALIA reported high Li leaching yields (>95%). Their future work will focus on the further optimisation of the operational conditions, more appropriate for the anticipated scalability phases of the process. On the other hand, solvometallurgical tests carried on waste cathode material achieved high leaching yields for all target elements (Li, Co, Ni, Mn) using mild operational parameters.
After the first experiments engaging reactive milling and aqueous leaching [treated with aluminium- (Al) and calcium (Ca) – salts] on waste cathode material, researchers at KIT reported close to 31% Li recovery rate. Samples supplied by UMICORE were leached under different conditions to extract Li – available in the form of Li carbonate [LiCO3], and further subjected to purifications processes employing various reducing agents. Future efforts for this particular task will focus on adjusting leaching temperatures, establishing an optimal purification process, and evaluating Li recoverability in both Al and Ca systems.
Anticipating future upscaling phases, researchers at VITO, working on the Li-sieve adsorption and desorption from aqueous leachates, shaped the lithium-titanium-oxide (LTO) adsorbents into spheres, which enabled dynamic testing. The team is currently optimising the flow rates for adsorption and desorption to model the optimal conditions for upcoming processes. While initial tests utilised synthetic Li solutions, upcoming research will extend to purification processes for spodumene leachates.
In the same work package, TECNALIA performed experiments using different organic solvents for the liquid/liquid (L/L) extraction from brines showing promising Li yields in the range of 40-60 %.
Within the same work package, EnBW scientific team has been working on designing an eco-friendly Li-desorption process from brines, focusing on the development of novel synthesis for Mn-based adsorbent material. Notably, the successful upscaling of the synthesis process from 2,5g to 200g marks a significant achievement in sustainable material synthesis.
Finally, the last task of WP5 – Electrode-based Li adsorption and desorption from brines, conducted by KIT, presented the conclusions of their research work carried during the last six months, which includes a 4-step process. Their work has been focusing recently on the optimisation of the electrode pre-treatment, the establishment of the current densities and the reduction of the Na contaminations. Despite high Li selectivity rates obtained thus far, their work in the upcoming months will centre around optimising the recovery efficiency and the selectivity. Future experiments will test different thermal operating conditions (40°, 60°, 80°), but will also attempt to scale-up the process.
In the final technical work package, SINTEF scientists are pioneering a two-step process which involves in a primary phase selective chlorination by converting insoluble oxides to soluble chlorides; this is followed by a second step – electrolysis of the soluble chlorides extracting the target elements. After conducting different chlorination experiments, researchers emphasised the importance of time and the processing duration, confirming over 65 % Li recovery rate. With promising results, their focus pivots towards the second step – electrolysis.
Read the next article for a comprehensive overview of the meeting.
Focusing on mechanochemical (MC) processing, the recovery of high-value components from the cathode waste supplied by UMICORE is planned to be performed within Task 4.3.
The ball milling process of waste cathode material was optimised at laboratory scale using different reducing agents such as Al, Ca, and their mixtures. The role of the MC conditions (ball-to-sample ratio (B/S), ball milling time, and nature of the reducing material) was further investigated and analysed. This showed the kinetics of the MC-induced reduction reaction is sensitive to multiple processing parameters.
After the reduction reaction, the powder X-ray diffraction (XRD) analysis revealed the formation of metallic composites and Al/or Ca oxides, as illustrated in the figure below. The upcoming research will be dedicated to investigating and optimising the aqueous leaching conditions of the ball-milled samples at laboratory scale.
XRD patterns of the MC processed cathode waste materials with Al and Ca as reducing agents