One-step conversion of sulfate lithium into high-purity lithium hydroxide crystals via bipolar membrane crystallization

To date, bipolar membrane electrodialysis (BMED) is being developed as a competitive technology for waste lithium-ion battery recovery. However, the purity and concentration of lithium hydroxide generated from a BMED plant could not meet the product criteria for ternary lithium batteries, thus requiring additional condensation, purification, evaporation, and crystallization procedures. Herein, bipolar membrane crystallization (BMC) was proposed for the one-step conversion of sulfate lithium into high-purity lithium hydroxide monohydrate crystals. By mediating a continuous saturated feedstock in the salt compartment, it is possible to convert Li2SO4 into 5+ mol/L LiOH at a current density higher than 500 A/m(2). Therefore, this unique design allows the production of 99.9% LiOH & BULL;H2O by taking the principle of water dissociation in the bipolar membrane and the simultaneous crystallization procedure. This proof-of-concept study proves the feasibility and competitiveness of the BMC for waste lithium recovery by abandoning the condensation and evaporation procedures.