High performance, pH-resistant membranes for efficient lithium recovery from spent batteries

Abstract

Abstract Cation separation under extreme pH is crucial for lithium recovery from spent batteries, but conventional polyamide membranes suffer from pH-induced hydrolysis. Preparation of high performance nanofiltration membranes with excellent pH-resistance remains a challenge. Here we synthesize a high performance nanofiltration membrane (1,4,7,10-Tetraazacyclododecane (TAD)−1,3,5-Tris(bromomethyl)benzene (TBMB) thin film composite membranes (TFCMs)) with excellent pH-stability through interfacial quaternization reaction between TAD and TBMB. Due to the high stability of “C-N” bonds in TAD-TBMB TFCMs, its separation performance is stable even after 70 days immersion in concentrated acid (3 M H2SO4, HNO3, or HCl) and base (3 M NaOH), which is at least 15 times more stable than benchmark commercial membranes. The membrane shows an overall separation performance (11.3 L m−2 h−1 bar−1 (LMHB), RCo2+: 97% in 2 M H2SO4) due to the size sieving and the intensified charge repulsion, outperforming many of the state-of-the-art membranes. Finally, the TAD-TBMB TFCM remains stable during 30-days continuous nanofiltration of 2 M H2SO4 and leachate (2 M H2SO4, ions: 6.2 g L−1) from spent batteries.