Chlor-alkali electrolysis for battery grade lithium hydroxide production as a pathway towards low-carbon lithium refining

Abstract

Lithium hydroxide (LiOH) is a critical precursor for nickel rich lithium-ion battery cathodes, with demand projected to grow rapidly over the next decade. Conventional LiOH production relies on multi-step chemical refining, which is energy intensive, reagent intensive and generates substantial byproduct streams. In this work, we evaluate LiCl based chlor-alkali electrolysis as a process intensified route for LiOH production and compare it with chemical routes and other electrochemical routes including bipolar membrane electrodialysis and electro-electrodialysis across energy use, CO 2 footprint and chemical waste generation. Our analysis shows that lithium chlor-alkali electrolysis for LiOH production is most compelling when LiCl is available at sufficient purity and when chlorine and hydrogen products can be valorized or internally recycled. Additionally, LiCl electrolysis also face Li specific ion transport limitations including bi-layer cation exchange membrane swelling, hydroxide crossover, electro-osmotic water drag and LiOH solubility limit, which constrain reaching higher current densities and higher faradaic efficiencies. We discuss strategies to improve these performance metrics and compare electrochemical LiOH production from spodumene, brine and battery leachate as Li sources. Further, we show that Flash Joule Heating technology could be coupled with chlor-alkali electrolysis to create a closed loop spodumene to LiOH process and discuss why the overall climate benefit of electrochemical routes strongly depend on electricity-grid carbon intensity. Overall, we posit that lithium chlor-alkali electrolysis represents a promising pathway for LiOH production, but its practical implementation will depend on advances in membrane design, process integration and electricity grid decarbonization.