Electrochemical lithium extraction based on “rocking-chair” electrode system with high energy-efficient: The driving mode of constant current-constant voltage

Benefiting from the high lithium selectivity and low electrode cost, electrochemical lithium extraction based on a “rocking-chair” electrode system of LiMn2O4/Li1-xMn2O4 is a promising approach to alleviate the shortage of lithium resources. However, the optimization of driving mode, a key factor affecting the lithium extraction performance, is neglected in previous researches. In this regard, the effect of driving mode on the lithium extraction process was comprehensively analyzed theoretically. The driving mode of constant current (CC) was considered to have a high energy efficiency, and it was verified by experiments. However, it showed a lower lithium extraction capacity than that with the driving mode of self-driven-constant voltage (SD-CV). On this basis, a collaborative driving mode of CC-CV was proposed with the combination merits including both high energy efficiency of CC and excellent lithium extraction capacity of SD-CV. With the optimized CC-CV driving mode and the introduction of stirring in the source solution, the lithium extraction capacity is up to 34.69 mg·g−1 within 85 min, and the corresponding specific energy consumption is only 6.76 Wh·mol−1 Li. These results demonstrate the developed CC-CV driving mode has excellent lithium extraction performance, which can push forward the application of this technology for sustainable lithium extraction.