A 10 nm Polyamide Membrane with an Asymmetric Charge Structure for Efficient Lithium Extraction

TY - JOUR

T1 - A 10 nm Polyamide Membrane with an Asymmetric Charge Structure for Efficient Lithium Extraction

AU - Yang, Yushuai

AU - Zhao, Yan

AU - Zhao, Shuang

AU - Yao, Ruxin

AU - Li, Hui

AU - Ma, Junhao

AU - Shi, Can

AU - Bai, Shengchi

AU - Wang, Xiaoqi

AU - Li, Jie

AU - Feng, Xiao

AU - Wang, Bo

N1 - Publisher Copyright: © 2026 American Chemical Society

PY - 2026/1/20

Y1 - 2026/1/20

N2 - Polyamide membranes are essential for lithium extraction from salt-lake brines, yet optimizing their ion-sieving efficiency remains difficult. Herein, we report an ultrathin polyamide membrane (∼10 nm thick) with a low surface roughness (Ra = 1.18 nm) and an engineered asymmetric charge distribution. The membrane combines a positively charged upper layer, a negatively charged lower layer, and an interfacial region with narrower pores formed via interlayer interpenetration. This architecture promotes differential dehydration of Mg2+ and Li+ at the upper layer and amplifies selectivity through the interfacial region. Passage through the positive layer increases ion charge exposure, enhancing diffusion selectivity within the negatively charged interior and raising the transmembrane energy barrier for Mg2+ relative to Li+. The membrane achieves a Li+/Mg2+ selectivity of 69 and a water permeation flux of 12 L m–2 h–1 bar–1, surpassing commercial benchmarks. Its ultrasmooth surface and high hydrophilicity minimize fouling, maintaining a flux recovery above 90% under high contaminant loads. Scaled-up modules using a three-stage nanofiltration process reduced the Mg2+/Li+ ratio in a concentrated brine simulant (25 g L–1) from 50 to 0.2, highlighting strong potential for industrial lithium recovery.

AB - Polyamide membranes are essential for lithium extraction from salt-lake brines, yet optimizing their ion-sieving efficiency remains difficult. Herein, we report an ultrathin polyamide membrane (∼10 nm thick) with a low surface roughness (Ra = 1.18 nm) and an engineered asymmetric charge distribution. The membrane combines a positively charged upper layer, a negatively charged lower layer, and an interfacial region with narrower pores formed via interlayer interpenetration. This architecture promotes differential dehydration of Mg2+ and Li+ at the upper layer and amplifies selectivity through the interfacial region. Passage through the positive layer increases ion charge exposure, enhancing diffusion selectivity within the negatively charged interior and raising the transmembrane energy barrier for Mg2+ relative to Li+. The membrane achieves a Li+/Mg2+ selectivity of 69 and a water permeation flux of 12 L m–2 h–1 bar–1, surpassing commercial benchmarks. Its ultrasmooth surface and high hydrophilicity minimize fouling, maintaining a flux recovery above 90% under high contaminant loads. Scaled-up modules using a three-stage nanofiltration process reduced the Mg2+/Li+ ratio in a concentrated brine simulant (25 g L–1) from 50 to 0.2, highlighting strong potential for industrial lithium recovery.

KW - asymmetric structure

KW - lithium extraction

KW - nanofiltration

KW - polyamide membrane

KW - ultrasonic-assisted atomization

UR - https://www.scopus.com/pages/publications/105027729140

U2 - 10.1021/acsnano.5c14567

DO - 10.1021/acsnano.5c14567

M3 - Article

C2 - 41486628

AN - SCOPUS:105027729140

SN - 1936-0851

VL - 20

SP - 2064

EP - 2072

JO - ACS Nano

JF - ACS Nano

IS - 2

ER -