Lithium extraction from brine in an ionic selective desalination battery

Abstract

With the increasing global demand for lithium, lithium extraction from seawater/brine attracted extensive attentions. Selective lithiation desalination battery is a novel and promising model for this process since its good performances on selectivity, extraction capacity and energy consumption. However, multi-metal composition and possible corrosiveness of seawater/brine requires high capacity electrode with high selectivity and cycle stability. To address this issue, this work proposed a less layer graphene gauze modified Ni-rich cathode material LiNi0.6Co0.2Mn0.2O2 core-shell structure microsphere (rGO/NCM) with shell thickness of 3 nm. The graphene gauze offers high electron transfer pathways instead of ion transfer between lattices, which reduced the NCM lattice collapse probability effectively. This was verified by ex-situ XRD and electrochemical results of high capacity, good cycle stability and rate performance in both organic and aqueous systems. In the desalination battery composed of rGO/NCM as positive and activated carbon (AC) as negative, rGO/NCM//AC delivered high Li+ extraction efficiencies reaching 13.84 mg/g per 1 cycle in simulated brine by consuming only 1.4 Wh/mol Li+. The overall process produced 93% Li+ in simulated brine at optimized operating conditions. The results indicated that rGO/NCM//AC desalination battery is a promising electrochemical lithium extraction approach.