Bacterial Cellulose/Lithium Magnesium Silicate Composite Membrane: Validating Microscopic Asymmetric Nanochannel For Enhanced Ion Transport and Mitigated Concentration Polarization

Abstract

The ion concentration polarization (ICP) effect in conventional layered nanofluidic membranes severely limits the osmotic energy conversion. Although heterojunctions have become the focus of research to mitigate ICP, the interfacial compatibility issue remains unresolved. In this study, a microscopic charge anisotropy (MCA) strategy is proposed to combine natural mineral lithium magnesium silicate (XLS) nanosheets with natural polysaccharide bacterial cellulose (BC) nanofibers to construct microscopic asymmetric nanochannels with high ion transport capacity. The resulting composite membrane not only solved the interfacial compatibility problem of heterogeneous junction, but also effectively mitigated the ICP effect of traditional laminated membrane. The power density of the membranes reached 10.4 W m−2 under artificial seawater/river water (0.5 M/0.01 M NaCl), and increased to 14.8 W m−2 when the channel length was optimized to 0.5 mm. Nine MCA membrane devices in series deliver 1.5 V to power the calculator. Given the excellent biocompatibility of bacterial cellulose (BC), the composite membrane holds promise as an implantable power source, providing energy support for bioelectronic devices. This MCA strategy is expected to provide a new solution for overcoming the ICP effect, improving traditional membrane materials, and advancing the development of osmotic energy conversion.

Keywords: osmotic energy conversion, ion concentration polarization, microscopic charge anisotropy, nanochannel, ion transport