Advanced Electrode Materials in Capacitive Deionization for Lithium Recovery

Demand for lithium batteries and lithium resources is growing because of the fast development of electric vehicles which will reach 900,000 metric tons per year by 2025. But the available lithium supplies are running out, and the future utilization of lithium resources will depend on strong productivity and resource recovery. However, current methods of extracting lithium ion resources still have the disadvantages of slow rates, unstable system outputs, and low purity. These methods can hardly compensate for the huge market demand in the future. The alternative technology, capacitive deionization (CDI) technology based on electrochemical ion pumping, provides a high capacity and rate of lithium resource recovery, which uses renewable electrode materials, reduces system waste generation, and has high lithium ion purity in the extract, which is sufficient to meet the future market demand. This mini-review analyzes the electrode materials used in CDI technology with a particular emphasis on the development of three materials, Olivine LiFePO4/FePO4, Spinel LiMn2O4/λ-MnO2, and Spinel LiNi0.5Mn1.5O4. The advantages and disadvantages of the current advanced materials are evaluated from various perspectives, and the feasibility of different electrodes is analyzed.