Multi-driven force coupled dialysis system for collaborative recycling of acid and lithium from spent LIBs leachate

Abstract

The continuous influx of waste batteries poses severe challenges to energy, economy, and the environment, particularly in major economies with high lithium-ion battery (LIB) usage. Selectrodialysis (SED) is considered for lithium recovery from spent LIB leachate via monovalent ion selectivity, but proton hopping through monovalent-selective cation exchange membranes in acidic media limits its selectivity and stability. This report describes a diffusion dialysis (DD)/SED integrated recycling system capable of acid recovery and subsequent lithium extraction. The efficient SED unit exhibits high lithium selectivity during spent LIB leachate reclamation, benefiting from the removal of acid (H⁺) from the feed stream via DD process. Appropriate running mode conditions contribute to excellent mass transfer for each unit. Specifically, DD operates in counter-flow mode with waste acid flowing from bottom-to-top, leading to >95% acid recovery. This performance is attributed to the uniform concentration distribution and adequate acid filtration. Meanwhile, SED under constant voltage mode reaching 7.9 (7.8) selectivity for Li/Ni (Li/Co) owing to its high Li electromigration rate constants (0.0273 ± 0.0003 min⁻¹) under changing current drop. Furthermore, the integrated DD/SED process recovers 92.3%-pure Li₂SO₄ from spent LIB leachate with reduced chemical input, achieving a gross profit of 42.22 USD/t while demonstrating enhanced sustainability and industrial potential.