Understanding the Behaviors of λ-MnO₂ in Electrochemical Lithium Recovery: Key Limiting Factors and a Route to the Enhanced Performance

Abstract

Recently developed electrochemical lithium recovery systems, whose operation principle mimics that of lithium-ion battery, enable selective recovery of lithium from source waters with a wide range of lithium ions (Li + ) concentrations; however, physicochemical behaviors of the key componentLi + -selective electrodein realistic operation conditions have been poorly understood. Herein, we report an investigation on a λ-MnO 2 electrode during the electrochemical lithium recovery process with regards to the Li + concentration in source water and operation rate of the system. Three distinctive stages of λ-MnO 2 originating from different limiting factors for lithium recovery are defined with regard to the rate of Li + supply from the electrolyte: depleted, transition, and saturated regions. By characterization of λ-MnO 2 at different stages using diverse X-ray techniques, the importance of Li + concentration in the vicinity of the electrode surface is revealed. On the basis of this understanding, increasing the density of the electrode/electrolyte interface is suggested as a realistic and general route to enhance the overall lithium recovery performance and is experimentally corroborated at a wide range of operation environments.

λ-MnO₂ Thin Films with Sponge-Like Structures: Synthesis, Characterization and Physiochemical Applications

“…2(a) offered that XPS Mn 2p region and an asymmetrical main of Mn 2p 3/2 peak in the presence of Mn 3+ and Mn 4+ (Fig. 2(b)), which in the present a multiplet splitting of the λ-MnO 2 spectrum with satellite peaks at 655 and 641 eV and it referred to MnO 6 octahedral body which is similar to the earlier studies [15,30].…”

“…65 V that is evidence for coinciding with the electrolyte apportionment and following the construction of solid electrolyte interphase (SEI) layer generation. In the anodic orientation, one peak of oxidation at 1.3 V signalize that attributable to the delithiation process from the lithiated manganese oxide matrices and the dissociation of Li 2 O [30][31].…”

Electrochemical approaches for selective recovery of critical elements in hydrometallurgical processes of complex feedstocks

“…The electrodes, λ-MnO 2 and Ag, were converted to Li x Mn 2 O 4 and AgCl x (0 < x < 1) when Li + was captured from the concentrate ( Joo et al., 2020 ). The mechanism of Li + recovery through λ-MnO 2 was thoroughly investigated by Kim et al., finding that increasing the density of the electrode/electrolyte interface can increase lithium uptake ( Kim et al., 2020d ). Lithium can also be selectively removed and up-concentrated using other intercalation cathode materials, such as LiFePO 4 coupled with a silver counter electrode.…”

Direct Lithium Recovery from Aqueous Electrolytes with Electrochemical Ion Pumping and Lithium Intercalation

“…The recovery capacities are strongly influenced by the current density, the lithium concentration in the source electrolyte, and the intercalation material crystal size. 34 The authors found enhancement of the overall lithium recovery by increasing the density of electrode/electrolyte interface.…”

“…However, under operation conditions less mass of lithium can be recovered per gram of LiMn 2 O 4 the higher the applied current and the lower the lithium ion concentration. 34 …”