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 Li_1.5Al_0.5Ge_1.5(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.