Lithion Technologies (also known as Lithion Recycling), a Canadian cleantech company founded in 2017, provides a hydrometallurgy-based technology that recovers 95% of lithium-ion battery components and regenerates high-purity materials that can be used in the production of new rechargeable batteries. This technology significantly reduces the demand for the extraction of new raw materials and minimizes the ecological debt of electric vehicles.
Challenges: lithium battery recycling
Lithium and cobalt are used in the production of lithium-ion batteries; these materials must be recycled because they have a significant environmental impact. Today, only a small number of spent lithium-ion batteries are recycled, and the method for recycling these batteries has a significant environmental impact and fails to recover a significant amount of valuable materials.
The elements of a spent lithium-ion battery can be separated using pyrometallurgical techniques. Components of organics and polymers are burned by heating at a high temperature. Cobalt, copper, and nickel are melted to create an alloy, while the remaining elements become slag. Metal smelters purchase metal alloys for separation. Significantly, lithium is lost in these processes and cannot be recovered or resold. The sold alloy has a fraction of the value of the pure and separated metals.
Hydrometallurgical processes are often used to separate and purify the different metals contained in the cathode. In order to obtain relatively pure metals, these processes typically involve a leaching step to dissolve the metals oxide into the aqueous solution and various precipitations and separations steps. These processes are still in development and are expensive to operate. Also, the treatment of liquid waste is usually barely taken under consideration.
There is a need to be provided with a process which can economically process all types of used lithium-ion batteries at large scale industrial processes.
Lithion Technologies Technology
Lithion Technologies provides a method for recycling lithium-ion batteries comprising the processes:
- shredding lithium-ion batteries and immersing the residues in an organic solvent to safely discharge the batteries, thereby producing shredded batteries residues and a liquid containing organic compounds and lithium hexafluorophosphate;
- feeding the shredded batteries residues into a dryer to generate a gaseous organic phase and dried battery residues;
- feeding the dried batteries residues containing magnetic and non-magnetic batteries residues to a magnetic separator that removes magnetic particles from the dried batteries residues;
- grinding the residues of non-magnetic batteries to a particle size of between 0.1 and 10 millimeters, which produces a particle size distribution containing plastics in an upper range and aluminum, copper, metal and graphite in the middle and lower range of fine particles;
- mixing fine particles with an acid to create a slurry, then leaching the slurry to produce a leachate containing metal sulfate and non-leachable materials;
- removing non-leachable materials from the leachate by filtering the leachate;
- leachate is fed into a sulfide precipitation tank, which removes ionic copper impurities from the leachate;
- adjusting the pH of the leachate to between 3.5 and 5 and removing any remaining iron and aluminum;
- mixing the leachate with an organic extraction solvent producing an aqueous phase containing lithium, sodium and nickel and an organic phase containing cobalt, manganese and the remaining nickel;
- crystallizing sodium sulfate from the aqueous phase containing lithium producing a liquor containing lithium and sodium sulfate crystals;
- adding sodium carbonate to the liquor and heating up the sodium carbonate and the liquor producing a precipitate of lithium carbonate; and
- drying and recuperating the lithium carbonate.
The used batteries are shredded. The shredded battery residues are immersed in an organic solvent to safely discharge the batteries, producing shredded battery residues and a liquid containing organic compounds and lithium hexafluorophosphate.
Why are shredded battery residues immersed in an organic solvent?
- The used batteries may contain residual charge. When the inside components of a charged battery are exposed to the ambient air’s moisture, an exothermic reaction occurs which produces hydrogen gas. This poses a severe risk of hydrogen gas combustion. To minimize the risk of combustion, used batteries are shredded and then immersed in an organic solvent.
- The organic solvent can also dissolve and extract electrolyte salts, such as lithium hexafluorophosphate (LiPF6), from battery materials. It is miscible with the electrolyte solvent (an aliphatic carbonate).
- In addition, the organic solvent will serve as a heat sink in the event of an exothermic reaction, thereby reducing operating hazards. The temperature of the organic solvent is maintained below 40 °C.
After shredding, the shredded battery residues and the solvent are extracted to ensure that the electrolyte salt is thoroughly washed. The extractant is the same solvent used in the step of shredding. The extraction is performed at temperatures between 40 to 60°C, with a residence time between 30 minutes to an hour and a half, and a tested operating point of 50 °C for 1 hour.
The shredded batteries residues or particles are then separated from the liquid through sieving or filtration.
Recycle electrolyte solvents
In the obtained liquid phase, electrolyte solvents and organic solvents used in the shredding step are separated by distillation and condensation. The diagram below depicts the solvent recycling process.
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