Lithium-ion electrosorption on lithium manganese oxide soft and bare electrodes

Abstract

Lithium is a critical resource for high-energy batteries and emerging energy storage technologies. Conventional extraction methods, such as solar evaporation of brines, are energy-intensive and environmentally harmful, highlighting the need for sustainable alternatives. Here, we present an electrochemical electrosorption strategy for selective lithium recovery using a hybrid intercalation-based electrochemical cell that exploits the unique properties of lithium manganese oxide (LMO). Unlike traditional carbon-based electrodes, LMO features a spinel crystal structure that enables reversible Li + intercalation under controlled potentials, providing intrinsic ion selectivity. To improve durability and performance, the LMO electrode was functionalized with the anionic polyelectrolyte poly(sodium 4-styrenesulfonate) (PSS). At the same time, the activated carbon counterelectrode was coated with the cationic polyelectrolyte poly(diallyldimethylammonium chloride) (PDADMAC). Experiments in single-salt (LiCl) and mixed-salt (LiCl + NaCl) systems, including highly asymmetric brines, reveal that Li + uptake strongly depends on the applied cell voltage, reaching values above 40 mg/g at 1.2 V. The PSS coating mitigates Mn dissolution and alters desorption dynamics, favoring Na + release while enhancing Li + retention. These results demonstrate the potential of LMO-based hybrid electrodes for energy-efficient lithium recovery from complex saline environments.