Novel production of basalt nanosheets with ultrahigh aspect ratios and their assembly with nylon membranes for high-performance electrical insulating composite membranes

Abstract

The rapid advancement of modern electrical equipment has significantly increased the demand for advanced electrical insulating materials. Traditional silicate nanosheets are widely used as fillers in electrical insulating composites. However, their low aspect ratio restricts their effectiveness in high-performance electrical insulating applications. Here, a three-step liquid exfoliation strategy is proposed to prepare basalt nanosheets (BSNs) with an ultrahigh aspect ratio (up to 1397) from basalt scales (BS). This process involves cation exchange on BS to generate lamellar structures, serving as the basis for the preparation of lithium ion-exchanged BSNs (LBSNs). Next, oxalic acid/hydrogen peroxide treatment breaks the chemical bonds within the LBS sediment, producing chemically treated BSNs (CBSNs). Finally, BSNs are prepared by mixing LBSNs and CBSNs, followed by differential centrifugation to isolate BSNs with an ultrahigh aspect ratio (BSNs-1000). Subsequently, inspired by the overlapping structure of pangolin skin, BSNs-1000 are assembled onto nylon membranes, forming biomimetic nylon/BSNs-1000 (N/B-1000) composite membranes with an overlapping surface structure. This structure forms an effective physical barrier, impeding charge and crack propagation, thereby significantly enhancing their electrical insulating and mechanical properties. The novel exfoliation method and biomimetic strategy provide effective approaches for developing advanced electrical insulating membranes for high-performance electrical equipment.