Porous organic polymers with heterocyclic crown ethers for selective lithium-ion capture

Lithium (Li) is a key resource of the 21st century. Despite that, Li is traditionally mined rather than obtained from maritime brines or secondary sources such as spent energy storage devices, owing to the difficulties in Li recovery. Herein, we present a porous organic polymer capable of capturing Li ions from aqueous solutions through highly pre-organized, heterocyclic crown ether-like pores in the polymer backbone. These features enable Li+ uptake capacities over 120 mg g−1 and selectivity versus highly competitive ions such as Na+, Ca2+, and Mg2+.