Efficient Lithium Extraction Using Redox-Active Prussian Blue Nanoparticles-Anchored Activated Carbon Intercalation Electrodes Via Membrane Capacitive Deionization

Abstract

In this study, we designed high-performance MCDI electrodes by compositing Li+ intercalation redox-active Prussian blue (PB) nanoparticles with highly conductive porous activated carbon (AC) matrix for the selective extraction of Li+ ions. We prepared a series of PB-anchored AC composites (AC/PB) containing different percentages (20%, 40%, 60%, and 80%) of PB by weight (AC/PB-20%, AC/PB-40%, AC/PB-60%, and AC/PB-80%, respectively). The AC/PB-20% electrode with uniformly anchored PB nanoparticles over AC matrix enhanced the number of active sites for electrochemical reaction, promoted electron/ion transport paths, and facilitated abundant channels for the reversible insertion/de-insertion of Li+ ions by PB, which resulted in stronger current response, higher specific capacitance (159 F g-1), and reduced interfacial resistance for Li+ transport. An asymmetric MCDI cell assembled with AC/PB-20% as cathode and AC as anode (AC//AC-PB20%) displayed outstanding Li+ electrosorption capacity of 24.42 mg g-1 and a mean salt removal rate of 2.71 mg g min-1 in 5 mM LiCl at 1.4 V with high cyclic stability. After 25 cycles, 95.11% of the initial electrosorption capacity was retained, reflecting its good electrochemical stability. This strategy demonstrates the potential of compositing pseudo capacitive redox material with Faradaic materials to design advanced MCDI electrodes for Li+ extraction applications.

Keywords: Lithium extraction, Membrane capacitive deionization, activated carbon, Prussian blue, Intercalation, desalination