A new high-efficiency process for Li+ recovery from solutions based on LiMn2O4/λ-MnO2 materials

Abstract The manganese loss of lithium ion-sieves was high in the acid desorption process. Thus, electrically switched ion exchange (ESIX) has been investigated attempting to recover Li+ from brine in recent years. A new high-efficiency process for Li+ recovery from solutions was successfully applied in this study based on LiMn2O4/λ-MnO2 structures. The adsorption and desorption happened simultaneously at positive and negative electrodes, respectively. The adsorption rates increased with the increasing operating voltages. The adsorption capacity was 3.5 mmol·g−1 under the optimal voltage (0.75 V). Besides, the adsorption rates and adsorption capacities were mainly affected by operating temperatures, initial Li+ concentrations in adsorption solutions, and initial Li+ concentrations in desorption solutions, respectively. All the experiments results showed lower manganese losses (less than 0.05%) in desorption than traditional methods (1.2%–2.5%). The XRD results denoted that the λ-MnO2 electrode converted into the LiMn2O4 electrode after adsorption. On the contrary, the LiMn2O4 electrode converted back into the λ-MnO2 electrode after desorption. Cyclic experiments indicated that the electrodes in the adsorption-desorption process exhibited excellent regenerability.