A 3D nm-thin biomimetic membrane designed by American scientists

Bionic materials have huge applications in the fields of industry and biomedicine. Among them, multi-functional membranes with high permeance and selectivity that can mimic nature's designs have tremendous industrial and bio-medical applications.In recent years, people have gradually realized the value of bionic nano-membrane materials, and its synthesis technology has also been rapidly developed.

Recently, American scientists have proposed a novel concept of a 3D nanometer (nm)-thin membrane that can overcome the shortcomings of conventional membrane structures.

The 3D membrane is composed of two three-dimensionally interwoven channels that are separated by a continuous nm-thin amorphous TiO₂ layer. This 3D architecture dramatically increases the surface area by 6000 times, coupled with an ultra-short diffusion distance through the 2-4 nm-thin selective layer that allows for ultrafast gas and water transport, ∼900 lm^-2h^-1bar^-1. The 3D membrane also exhibits a very high ion rejection (R ~100% for potassium ferricyanide) due to the combined size-and charge-based exclusion mechanisms. The combination of high ion rejection and ultrafast permeation makes our 3DM superior to the state-of-the-art high-flux membranes whose performances are limited by the flux-rejection tradeoff.

It is worth mentioning that, as one of the key materials of lithium batteries, the separator can isolate the positive and negative electrodes and prevent electrons from passing through, while allowing ions to pass through, thereby completing the rapid transmission of lithium ions between the positive and negative electrodes during the charge and discharge process. Important role. The performance of the diaphragm directly affects the internal resistance, discharge capacity, cycle life and battery safety performance of the battery. The final Li⁺ selectivity of this 3D bionic nanomembrane exceeds that of polysulfides or gases, which is expected to solve major technical challenges in energy storage such as lithium-sulfur or lithium-O₂ batteries.

Reference: Tongshuai Wang, et al. 3D nm-Thin Biomimetic Membrane for Ultimate Molecular Separation. Materials Horizons, 2020.DOI: 10.1039/d0mh00853b