Electrode design and performance of flow-type electrochemical lithium recovery (ELR) systems

Abstract

Due to increasing interests in carbon neutral engineering, global market demand for lithium compounds is steadily growing, which serve as key compounds in the battery production. As a sustainable alternative for lithium compound production, electrochemical lithium recovery (ELR) is being studied extensively in recent years. However, research efforts for ELR have been mainly devoted to the synthesis of electrode materials, leaving an open problem of comprehensively understanding the effects of multiple electrode design parameters on the system performances. In this study, to address such a problem systematically, the ELR system with λ-MnO2/LiMn2O4 (LMO) electrodes is numerically investigated at a low current density of 62.5 μA/cm2. Three electrode design parameters are selected, which are known as key parameters in the literature: effective radius of LMO particles (rp), volume fraction of LMO particles in electrodes (εs), and electrode thickness (δ). Under the parameter range considered, the specific mass of Li+ recovered (qLi+) took the value ranging from 35.71 mg/g to 37.66 mg/g, while the range covered by the net energy consumption (Wnet) was from 0.17 Wh/mol to 5.44 Wh/mol. Sensitivity analysis showed that, with increasing rp, qLi+ decreases and Wnet increases, while opposite correlations were observed for εs and δ. It was also shown that the maximum of qLi+ and the minimum of Wnet can be achieved only with small rp (regardless of εs and δ), making it the most important parameter.