LAUSR

Significance With the rapid market penetration of electric vehicles, securing lithium supply has become increasingly critical. However, the traditionally used lime–soda evaporation process is time-consuming, chemical-intensive, and applicable solely to concentrated Li brines. Electrochemical intercalation has emerged as a highly selective method, which enables Li extraction from more dilute unconventional water sources (UWS), including oil- and gas-produced water, geothermal brines, and rejected brines from seawater desalination. Here, with an FePO4 model host, we reveal the different roles of major ions in Li competition and define that the key challenge to realizing Li mining from UWS and broadening minable sources is to improve the Li+ to Na+ selectivity, which can be achieved via further EDL and host materials design.