Selective extraction of lithium from salt lake brine by in situ crosslinked stable three-dimensional network film electrodes

Abstract

Water-soluble binders for electrode preparation offer advantages over traditional PVDF, including environmental benefits, improved electrochemical performance, and improved mechanical properties. The trend is to find environmentally friendly binders that are compatible with water-based processes. In this context, we designed and synthesized aqueous binders with three-dimensional crosslinked structures. These structures are based on highly branched, hydrophilic polyvinyl alcohol and lithium carboxymethyl cellulose, which facilitates Li+ transport. Furthermore, LiMn2O4/C/PVA-c-CMCLi film electrodes were prepared through covalent crosslinking. The film electrode was superior to the LiMn2O4/C/PVDF film electrode in terms of adsorption capacity (25.53 mg·g−1), but comparable to the LiMn2O4/C/PVDF film electrode in terms of cyclic stability (96.38 % capacity retention after 50 CV cycles). They also showed a shorter time to reach the adsorption equilibrium (2 h) and high selectivity for Li+ in simulated brine with a high Mg2+/Li+ ratio (40) from East Taijiner. This is attributed to the synergistic effects of the improved electrolyte wettability, enhanced adhesion strength through covalent crosslinking, and increased Li+ transport rate facilitated by -COOLi in CMCLi. These results indicate that this binder has the potential to replace PVDF in the preparation of film electrodes for extracting Li+ from brine with high Mg2+/Li+ ratios.