Lithium extraction from salt-lake
brine is important to ensure
a sustainable supply of lithium and meet its increasing demand for
use in electric vehicles and large-scale energy storage devices. However,
it remains challenging to separate Li+ ions from coexisting
ions in the brine. Here, we propose a combined strategy of a core–shell
structure and hydrophilic modification of a Li1.6Mn1.6O4 electrode to efficiently extract lithium from
brine with a high sodium ion content. Core–shell Li1.6Mn1.6O4@carbon was derived from polydopamine-encapsulated
Li1.6Mn1.6O4 via calcination. The
∼2 nm carbon shell protects Mn from leaching during lithium
extraction. Compared with bare Li1.6Mn1.6O4, the lithium extraction capacity of the modified electrode
increases from 20 to 39.6 mg/g in a brine with a high Na–Li
ratio (Na/Li = 44.78 by weight). The coating of polydopamine on the
Li1.6Mn1.6O4@carbon electrode reduces
the water contact angle from 119 to 86.9°, resulting in a hydrophilic
surface. Using an electrochemical adsorption method, the lithium extraction
capacity and desorption ratio reach 65.6 mg/g and 86.0%, respectively,
which are superior to the performance of the current membrane capacitive
deionization and electrochemical method. The modified electrode shows
high lithium-ion selectivity and excellent stability due to the reversible
redox reactions during lithium extraction/release. The strategy proposed
here provides insights into the structural design of electrodes for
the highly efficient separation of lithium from brine.
Salt lake brine has become a promising lithium resource, but it remains challenging to separate Li + ions from the coexisting ions. We designed a membrane electrode having conductive and hydrophilic bifunctionality based on the H 2 TiO 3 ion sieve (HTO). Reduced graphene oxide (RGO) was combined with the ion sieve to improve electrical conductivity, and tannic acid (TA) was polymerized on the surface of ion sieve to enhance hydrophilicity. These bifunctional modification at the microscopic level improved the electrochemical performance of the electrode and facilitated ion migration and adsorption. Poly(vinyl alcohol) (PVA) was used as a binder to further intensify the macroscopic hydrophilicity of the HTO/RGO-TA electrode. Lithium adsorption capacity of the modified electrode in 2 h reached 25.2 mg g −1 , more than double that of HTO (12.0 mg g −1 ). The modified electrode showed excellent selectivity for Na + /Li + and Mg 2+ /Li + separation and good cycling stability. The adsorption mechanism follows ion exchange, which involves H + /Li + exchange and Li−O bond formation in the [H] layer and [HTi 2 ] layer of HTO.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.