Li-Ions Pre-intercalation Strategy of Manganese Oxides for Capacitive Deionization-Based Selective Lithium Extraction From Low-grade Brine

In this work, Li preintercalated lambda-LixMnO2 with tunable lithium content is synthesized, which exhibited excellent electrochemical performance and dual-mode electrochemical storage behavior. Double-layer capacitive and diffusion-controlled Faradaic processes play a role in the charge-discharge process, leading to an enhanced lithium selective adsorption capacity. When employed in hybrid capacitive deionization (HCDI), the lambda-Li1.5MnO2 obtains a Li+ adsorption capacity of 33.68 mg g-1 in 32.74 mg L-1 Li+ ion solution and low energy consumption of 0.19 Wh g-1. Moreover, the lambda-Li1.5MnO2 electrode exhibited outstanding cycling stability, with a significant capacity retention rate of 80% and a manganese mass dissolution rate of 1.2% over 100 intercalation/deintercalation cycles. lambda-Li1.5MnO2 achieved outstanding lithium selectivity with a separation factor approximate to 32.7 at a Mg2+/Li+ molar ratio of 30 in synthetic brine. Importantly, lambda-Li1.5MnO2 achieved a high Li+ adsorption capacity and good selectivity in Lop Nor, the low-grade original brine of the XieLi salt flats, making it a candidate electrode for lithium extraction from low-grade original brine. The pre-intercalation strategy offers a viable option for rationalizing other intercalation electrode materials for electrochemical lithium extraction from low-grade original brine.