Simultaneous and precise recovery of lithium and boron from salt lake brine by capacitive deionization with oxygen vacancy-rich CoP/Co3O4-graphene aerogel

Lithium and boron recovery from salt lake brine is highly important for resource utilization and environmental risk reduction, particularly as an alternative source of the critical raw lithium materials for lithium ion batteries. This study develops a novel capacitive deionization (CDI) method to simultaneously and precisely extract Li+ and B(OH)4− ions from salt lake brine with high Mg/Li ratio. Using oxygen vacancy-rich CoP/Co3O4-graphene aerogel (GA/CoP/Co3O4) as the bifunctional anode and cathode, the effective adsorption capacity of Li+ and B(OH)4− ions reached 37 mg/g and 70 mg/g, respectively at the Mg/Li ratio of 24:1 and Cl/B ratio of 70:1. The excellent selectivity and efficiency could be attributed to the synergistic effect of rich oxygen vacancy, better hydrophilicity, flexible P-metal interaction and low internal resistance. The CDI system also has a good and stable performance of electrochemical adsorption-desorption, reaching >92% of recovery after 10 cycles. This paper provides a green and efficient method for recovery of valuable elements from salt lake brine and reduction of environmental risk.