Dual-function electrochemical cell for simultaneous carbon capture and lithium extraction from saline waters

Abstract

Effective utilization of saline waters as a large reservoir of both dissolved inorganic carbon (DIC) and lithium would simultaneously support carbon mitigation and secure critical mineral supply. Here, we report the first demonstration of a dual-function electrochemical system capable of coupling CO2 capture and Li+ extraction from saline waters. Using a pH-swing architecture with bismuth and LiFePO4 electrodes, we achieve stable pH cycling between 8.1 and 4.7 in 2.1 mM DIC, while extracting lithium at concentrations down to 0.17 ppm Li+ (seawater levels). Under impurity-free conditions, the system maintains 80% bismuth utilization and 50% lithium utilization, with attractive energetic costs of 128 kJ mol−1 CO2 and 121 kJ mol−1 Li, comparable to state-of-the-art stand-alone electrochemical systems. By integrating Li+ and CO2 extraction using shared pumping, membrane, and reactor infrastructure, this system offers a compelling path toward co-production of critical materials and integrated CO2 capture using a single seawater-processing platform.