Single Lithium-Ion Conductor Decorated LiMn2O4 with High Selectivity and Stability for Electrochemical Lithium Extraction

Spinel LiMn2O4 (LMO) is commonly used for electrochemically extracting lithium ions from brine. However, its cycle stability is significantly reduced due to Mn2+ dissolution. Here, we report high-performance LMO particles decorated by Li1.5Al0.5Ge1.5(PO4)3 (LAGP) as an electrode for electrochemical lithium extraction. Compared with bare sample, the modified electrode presents higher Li-ion selectivity because LAGP is a single Li-ion conductor, and as a result of avoiding the cointercalation of other ions in brine, the sample exhibits a higher Li-ion extraction capacity of 2.44 mmol·g–1. The cycling stability is also improved in LMO with LAGP coating by alleviating the loss of manganese, indicating a reduced Mn loss of 0.20% after 100 cycles compared to the LAGP free counterpart of 0.47%. Our work demonstrates an effective method for lithium purification from brine, and the detailed mechanism is also studied systematically.