Scaling‑free electro‑membrane crystallization enabled by electric field-assisted organic acid control

Mineral scaling, driven by concentration polarization, is an inevitable challenge in electro-membrane technologies for recovering valuable metals from lithium-ion battery (LIB) leachates. Here, we elucidate the synergistic scaling mechanism and propose an electric field-assisted organic acid control (eF-OAC) principle to prevent membrane mineral scaling while enabling metal recovery. The eF-OAC utilizes an electric field to direct organic acids into the membrane matrix, where ligand-metal coordination dissolves hydroxide-rich scale and mobilizes metal species for selective transport and crystallization. Dynamic experimental analysis reveals that concentration polarization enriches metal hydroxides at the membrane interfaces and pores. Static density functional theory calculations further demonstrate that organic ligands are thermodynamically favored over sulfonate groups for coordinating metal hydroxides, enabling targeted dissolution from the membrane. Leveraging this molecular-level selectivity, the eF-OAC converts scale into recoverable crystalline products. In optimized electro-membrane crystallization, this eF-OAC achieves high recovery rates of 97.6% for Li⁺, 95.3% for Ni²⁺, 94.2% for Co²⁺, and 97.8% for Mn²⁺. It further yields high-purity Li₂SO₄ (99.4%), Ni(OH)₂ (99.2%), Co(OH)₂ (99.0%), and Mn₃O₄ (99.3%). This study clarifies the mechanisms of mineral scaling and demonstrates a scaling-free approach that transforms fouling liabilities into valuable resource recovery for spent LIBs.