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Considering the growing global demand for lithium resources for electric vehicles and 3C products, it is urgently required to develop reliable lithium recycling technology. Hybrid capacitive deionization (CDI) has been regarded as a promising eco-friendly method for the extraction of lithium from seawater and brines due to its excellent cycling efficiencies and reversibility. In this work, a rod-shaped Fe 3 O 4 /N-doped carbon (FO/NC) architecture was successfully synthesized via initial hydrothermal processing and subsequent in-situ carbonization and used as HCDI electrode. Owning to its unique structure feature and the desirable chemical composition, the rod-shaped FO/NC electrode showed a high lithium-ion extraction capacity of 0.57 mmol g −1 after 50 cycles at 1.2 V with good cyclability performance. More importantly, the FO/NC electrode exhibited exceptional Li + selectivity (the Li + /Mg 2+ separation factor α M g + L i + = 61.7 at low Li + /Mg 2+ molar ratio (1:1); and α M g 2 + L i + = 1.37 , α k + L i + = 1.83 , α N a + L i + = 2.29 , α C a 2 + L i + = 1.62 in a synthetic salt-lake brine). FO/NC electrode exhibited better selectivity for Li + ions over other ions, which also have been confirmed via Density Functional Theory calculations, stemming from their greater adsorption energy for Li + ions. FO/NC should be a highlighting candidate electrode for lithium extraction from unconventional sources such as seawater and brines. • A facile strategy was developed to synthesize rod-shaped Fe 3 O 4 /N-doped carbon (FO/NC). • FO/NC was used as electrode of hybrid capacitive deionization for extracting Li + . • FO/NC exhibited a superior Li + extraction performance with good Li + selectivity.
Wan et al. (Sat,) studied this question.