In situ construction of rod-shaped Fe3O4/N-doped carbon architecture with superior lithium-ion extraction performance via employing hybrid capacitive deionization system
Lijia Wan, Tingting Zhang, Hu Li, Qiaofeng Huang, Junping Hu, Likun Pan
Abstract
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.