Electrochemical impedance spectroscopy study of the LixMn2O4 interface with natural brine

Abstract The LiMn 2 O 4 -Polypyrrole electrochemical cell has been shown to extract LiCl from natural brine at low voltage with high selectivity, low energy consumption (5–10 Wh·mol − 1 ) and good stability. The intercalation/de-intercalation of Li + ions in Li x Mn 2 O 4 (0 ≤ x ≤ 1) has been studied by electrochemical impedance spectroscopy (EIS) at different potentials and lithium ion concentrations using a modified Randles equivalent electrical circuit for the interface of Li x Mn 2 O 4 in natural brine from Salar de Olaroz (Jujuy, Argentina). The R CT exhibits two minima at potentials which correspond to x = 0.25 and x = 0.75 (half filled adsorption sites) respectively and a linear lithium ion concentration dependence of (Li + ) − 0.5 consistent with a lithium ion transfer adsorption model proposed by Bruce.