Water Molecules Eliminate Brute Force From MXene Nanosheet Production

Key Takeaways

• Water‑mediated scission yields 84.7% exfoliation efficiency.
• Produced MXene sheets average 10.46 µm lateral size.
• Conductivity reaches ~11,000 S cm⁻¹, highest reported.
• Lithium‑selective membranes achieve 177× Mg selectivity.
• Kilogram‑scale production enables roll‑to‑roll 100 m membranes.

Pulse Analysis

The water‑mediated scission technique redefines MXene exfoliation by leveraging chemistry instead of brute force. Lithium ions intercalated between layers attract water molecules, forming hydrated clusters that physically pry the sheets apart. Over a 12‑hour soak, hydrogen‑bond networks replace rigid electrostatic bonds, allowing a gentle vortex shear to complete the process. This approach eliminates the lattice damage typical of ultrasonic cavitation, delivering monolayer sheets with only 0.36% strain and preserving the material’s intrinsic metallic conductivity.

Performance metrics underscore the method’s industrial relevance. The exfoliated nanosheets reach an unprecedented conductivity of roughly 11,000 S cm⁻¹, a direct result of their large lateral dimensions and near‑perfect crystal lattice. Tensile strength of the assembled membranes climbs to 72.27 MPa, three times higher than those produced by conventional methods, while maintaining flexibility for complex form factors. Crucially, the process scales to kilogram quantities, supporting a continuous roll‑to‑roll line that fabricates 100‑meter‑long membrane rolls with consistent lithium permeation and selectivity across dozens of test points.

The most compelling application lies in seawater lithium extraction, a strategic avenue for meeting future battery demand. The defect‑free MXene membranes form nanofluidic channels of about 6 Å, allowing lithium ions to pass while rejecting larger hydrated magnesium and calcium ions. Selectivity reaches a 177‑fold advantage for lithium over magnesium, and pilot tests on real seawater achieve a 36% lithium recovery in a single pass with less than 3% competing ion permeation. By marrying scalable production with superior separation performance, this technology could catalyze a new supply chain for critical minerals, reducing reliance on terrestrial mining and supporting the clean‑energy transition.