In situ growth of LiMn2O4 on graphene oxide for efficient lithium extraction by capacitive deionization.

Selective extraction of lithium from brines has attracted significant interests with the rapid development of lithium battery industry. LiMn2O4 (LMO) is a typical lithium intercalation material with good redox activity and high theoretical adsorption capacity. However, the poor conductivity and stability of LMO lead to its performance deterioration. Here, LMO was in situ grown on graphene oxide flakes (LMO/GO) by pre-synthesis of Mn3O4 in the presence of GO followed by hydrothermal lithiation. Cyclic voltammetry and galvanic charge/discharge demonstrated the in situ synthesis of LMO on GO and enhanced the reversibility of the redox process and the rate performance of LMO. By adjusting the GO amount, the resultant LMO/GO electrode presented a high adsorption capacity and excellent selectivity for Li+ adsorption in capacitive deionization device. In contrast with pure LMO, the stability and adsorption capacity of LMO/GO were drastically improved with the capacity retention of 80% in 150 cycles. The effect of the other cations (K+, Na+, Mg2+, Ca2+) on Li+ adsorption was negligible, and the separation factor reached 47.8 at a Li/Mg molar ratio of 30. When applied for synthetic brine, the electrode held high Li+ adsorption amount of 720.2 μmol g−1, demonstrating the feasibility of LMO/GO for Li+ extraction from brine. [ABSTRACT FROM AUTHOR]