NSERC-DFG SUSTAIN: ION-SIEVING CAPACITIVE EXTRACTION OF LITHIUM from Alberta Oilfield Brine towards Sustainable Supply Chain

对锂的需求不断增加，特别是与汽车行业向电动汽车的转变有关，需要开发替代方法和额外的供应来源。目前，锂的提取依赖于硬岩矿石和大陆卤水，使用蒸发和化学技术。然而，预计未来几年对锂的需求不断增加，以及对这些方法可持续性的担忧，需要为这一供应链找到替代方法。此外，在加拿大、德国等地，这些技术无法有效应用的低浓度盐水都是可用的，将能够为锂供应链做出重大贡献。在这里，主要问题之一依赖于锂离子与其他竞争离子（如钠、镁等）的有效分离。在此，我们提出了一种创新的方法，基于离子筛分电容去离子选择性提取锂的低锂浓缩卤水，如阿尔伯塔油田卤水。电容去离子是一种方便的方法，因为它能够在低施加电位下存储离子并在放电时有效地释放它们。为此，将在具有非常高表面积的杂原子掺杂碳的表面上沉积具有纳米孔的薄离子筛分层，该纳米孔选择性地使锂离子能够穿过该层传输，以储存大量的锂。碳材料和离子筛分层的设计是实现高选择性和高锂吸附容量的基础。最终，我们设想这项技术将能够实现锂离子的连续分离，为选择性电容去离子领域的创新铺平道路，从而实现更可持续的锂供应链。

The increasing demand for lithium, especially related to the shift in the automotive industry towards electric vehicles, calls for alternative methods and additional supply sources to be exploited. Currently, the lithium extraction relies on hard-rock ores and continental brines, using evaporating and chemical technologies. However, the increasing demand for lithium expected in the next years and the concerns about the sustainability related to these methods requires to find alternative methods for this supply chain. Furthermore, less concentrated brines, where these technologies cannot be efficiently applied are available both in Canada, Germany, and more and would enable to provide a significant contribution to the lithium supply chain. Here, one of the main problems relies on the efficient separation of lithium ions from other competitive ions, such as sodium, magnesium, and more. Herewith we propose an innovative method based on ion-sieving capacitive deionization for the selective extraction of lithium from low-lithium concentrated brines, such as the Alberta oilfield brines. Capacitive deionization is a convenient method as it enables to store ions under low applied potentials and effectively release them upon discharge. For the purpose, a thin ion-sieving layer with nanopores that selectively enable the transport of lithium ions across the layer will be deposited on the surface of a heteroatom-doped carbon with very high surface area to store high amounts of lithium. The design of the carbon material and the ion-sieving layer is fundamental to achieve high selectivity and high lithium adsorption capacity. Eventually, we envision that this technology will enable to achieve continuous separation of lithium ions paving the way for innovation in the field of selective capacitive deionization towards a more sustainable lithium supply chain.