Highly Selective Lithium Recovery from Brine using LNCM/Ag and LNMO/Ag Battery System = Highly Selective Lithium Recovery from Brine using LNCM/Ag and LNMO/Ag Battery System

다국어 초록 (Multilingual Abstract)

Lithium shortage is inevitable due its massive demand growth for use in electric vehicles (EVs) and various technologies. Therefore, recovery of lithium from other sources such as seawater, brine, and Li-containing wastewater has been gaining attention in energy-related fields. However, the challenge is to find an environmentally benign and energy-efficient processes with fast Li⁺ production rate for sustainable Li⁺ supply. Electrochemical Li⁺ recovery from aqueous solutions is an attractive method as it provides fast recovery rate. However, several studies on this process are challenged with the stability of the materials in aqueous environment and large amount of energy needed entailing high production cost. Until recently, electrochemical related Li⁺ extraction has yet to realize its feasibility for industrial-scale application. The success of electrochemical method relies on utilizing highly effective electrodes that can selectively capture Li⁺ at a fast rate and at a competitive uptake capacity with minimal energy requirement. Delithiated Li_1-xNi_1/3Co_1/3Mn_1/3O₂ (NCM) or Li_1-xNi_0.5Mn_0.5O₄ (NMO) paired with silver (Ag) were introduced as new electrochemical systems for Li⁺ recovery from brine. Material and electrochemical characterizations confirm Li⁺ selectivity and stability of NMO/Ag or NCM/Ag in aqueous phase. Using brine as Li⁺ feed source, NMO/Ag or NCM/Ag electrochemically captured Li⁺ and Cl- at an applied current (C-rate) and operation time (min step-1). Reversal of the current in a receiving solution prompted the release of LiCl. Under optimal conditions, NCM can produce 96.4% pure Li⁺ from brine by expending 2.60 W·h mol^-1 Li⁺ while NMO can produce 98.1% pure Li+and expending 1.30 - 1.50 W·h mol^-1 Li⁺. In cycled experiments (n = 20), NMO/Ag and NCM/Ag can selectively accumulate Li⁺ from brine demonstrating its stability. These promising results indicate that both electrochemical systems can be developed for highthroughput Li⁺ mining process with low energy requirement. This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education(2018R1D1A1B07048007).