Reaching net-zero greenhouse gas emissions by 2050 will require a sevenfold increase in the supply of critical metals. Today’s production and purification of these metals remains heavily reliant on energy-, water-, chemical-, and land-intensive processes such as solvent extraction, ion exchange, and solar evaporation ponds. Through the Future Leaders Fellowship, I will build a team to lead the development of new materials and processes to recover critical metals from complex mixtures, including brines and recycling leachates, using membranes. My team’s research will develop a strong mechanistic understanding of selective mass transfer in concentrated, multi-ion mixtures, coupled with high-throughput experiments and spectroscopy, to build a generalisable framework for next-generation membrane and process design. Over the longer term, the fellowship will accelerate the technical and leadership development of both me and my team to drive forward separations science at the heart of the clean energy transition.