NSERC-DFG SUSTAIN: Prussian White for Sustainable Separation and Purification Technologies

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Storing 1 TWh of energy in lithium-ion batteries requires ~100,000 tons of lithium. Lithium mines can consume up to 50,000 liters of water a day and more than half of today's lithium production is in areas with high water stress. The resource limitations associated with the scale-up of battery production (2-6 TWh/year in 2031) require alternative extraction methods for lithium. At the same time, freshwater scarcity is already prevalent in many world regions. In this interdisciplinary and international project proposal "desa-LiNa-te" between Dalhousie University (Halifax) and Karlsruhe Institute of Technology (KIT), the overarching goal is to develop novel, cost effective and energy efficient separation and purification technologies for Li- or Na-ions from brine or sea water by means of electrochemical methods. Current bottlenecks with respect to material longevity, selectivity and scalability will be addressed by building a platform around the material class of Prussian White that will be tailored to Li-extraction and desalination processes. The basis of our material development approach is a computational framework that drives understanding of cation insertion selectivities and origins of degradation processes in aqueous media with high salinity. To further identify process-related roadblocks material deterioration and inhibition will be studied in detail by bulk and surface-sensitive analytical techniques. This knowledge will be leveraged to develop protection mechanisms and regeneration procedures to ensure long cycle life and high energy efficiency. The desalination and extraction of alkali metals can be conducted in different cell setups by either using a "tandem" (available at DAL) or a "dual-ion" (available at KIT) approach. Within the framework of "desa-LiNa-te" both technologies will be advanced jointly by the partners. The objective is to enable novel desalination cells that surpass the energy efficiency of state-of-the-art reverse osmosis desalination (~4 kWh/m3 freshwater), which would represent a step change in freshwater generation technology. Similarly, the electrochemical lithium extraction processes developed in this program target Li extraction selectivity of >98 % and production of highly Li-enriched brine solutions, while reducing freshwater consumption and extraction times. Exploring this technology for geothermal brines, recycling waste waters or brine reject from desalination opens new avenues to supply the exponentially growing battery industry with ethically mined lithium. Added value comes from the development of novel highly versatile Prussian White insertion materials, which will advance Canada's and Europe’s strategic initiative for battery supply chains. This project will provide a unique training experience for highly qualified personnel in battery process technology, e.g., materials synthesis and electrode coating.