Pre-seeding lithium in 1D olivine hosts for Li extraction

SUMMARY

• Lithium (Li) is a highly reactive alkali metal with excellent heat and electrical conductivity properties, making it useful for a variety of industrial applications, but because of its reactivity, pure elemental Li is not found in nature. Most commercial Li extraction processes involve mining to reach underground deposits of Li-rich mineral ores (30%) or extraction from geothermal well brines (70%). The demand for Li will increase dramatically due to its need in battery applications such as electric vehicles and consumer electronics. Seawater and brines are a promising supply of Li, though they may be in very low concentrations among with other ions. A reliable Li extraction method from these sources would find high commercial value.

• Current extraction techniques primarily rely on evaporating seawater/brines to concentrate the Li, but these require extensive land use and time. Additionally, seawater/brines contain a variety of dissolved ions (e.g., Na), many of which are present in much greater quantities than Li, making the capture of Li over other dissolved chemical species very challenging. As a result, it is nearly impossible for traditional separation techniques to extract Li from seawater/brines without excessive energy consumption, fouling of filtration media, and/or use of chemical regenerants. To date these processes have proved uneconomic.

• Inventors at the University of Chicago have developed a technique for Li extraction from dilute waters/brines. The technology utilizes the 1D olivine compound FePO₄ as a host material to control Li selectivity by manipulating the intercalation pathway. Results showed that Li and Na phase separate in FePO_4. This phase separation can be utilized to increase Na intercalation energy barrier through creation of partially filled 1D Li channels by a non-equilibrium solid solution Li seeding process. Li seeding into the host FePO₄ material is achieved through electrochemical/chemical processes.

• The developed platform as evaluated through density functional theory and structural characterization (e.g., XRD, SEND, EDS) demonstrated increased Li extraction selectivity post seeding, exhibiting a strong correlation with the fraction of high Li solid solution phase (e.g., Li_xFePO₄ 0.5≤x˂1). The high Li solid state phases prevented Na intercalation and remained intact even after pure Na intercalation.

FIGURE

Li and Na Phase Separation in FePO₄ Host  

ADVANTAGES

ADVANTAGES

• Increased Li competitiveness during Li extraction
• Improved Li selectivity as compared to other minerals (e.g., Na)
• Enhanced Li extraction performance as compared to mining and brine evaporation technologies

APPLICATIONS

• Li batteries in cell phones/mobile devices, electric/hybrid vehicles, electronics
• Li based energy storage systems
• Improved economics and efficiency for increasing global Li supply as compared to current Li production operations

PUBLICATIONS

• Yan, G., Kim, G., Yuan, R. et al. The role of solid solutions in iron phosphate-based electrodes for selective electrochemical lithium extraction. Nat Communications 13, 4579 (2022). https://doi.org/10.1038/s41467-022-32369-y