Sustainable approach for selective lithium recovery: Capacitive deionization integrated with novel LMO flow-electrode

Reusing materials from discarded batteries offers an environmentally friendly approach to lithium ion(Li+) recovery. Therefore, in this study, flow-electrode capacitive deionization (FCDI) was employed using lithium manganese oxide (LMO) from spent batteries to selectively recover Li+ from leachate. The Li+ selectivity of LMO enabled effective recovery from waste solutions containing various ionic substances. Delithiation of the LMO to produce 2-MnO2 enhanced its Li+ adsorption capacity. Successful synthesis was confirmed through field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) analyses, while BET analysis validated the suitability of the process for Li+ intercalation and deintercalation. XPS analysis confirmed the presence of Co2+, Ni2+, and Li+ in the electrode material at each stage, verifying the successful adsorption and recovery. CV and electrochemical impedance spectroscopy (EIS) analyses showed lower charge transfer resistance and higher ionic conductivity for the 2-MnO2 electrode as compared to activated carbon (AC), indicating its superior electrochemical performance. The 2-MnO2-based FCDI system outperformed the AC-based system; its removal rate was 3.08 times higher, specific energy consumption (SEC) was 2.6 times lower, and average salt adsorption rate (ASAR) was 5.1 times greater. Adsorption and recovery experiments indicated higher selectivity for Li+ ions as compared to Co2+ and Ni2+ ions, further highlighting the superior performance of the 2-MnO2 based system. In conclusion, the 2-MnO2 electrode, recycled from spent lithium-ion batteries (LIBs), is not only an excellent material for high-efficiency and selective lithium recovery via the FCDI process, but also holds the potential to revolutionize sustainable lithium recovery technologies. This study is a significant step towards addressing the climate crisis, promoting environmental protection, and conserving our valuable resources.