Template‐Catalyzed Mass Production of Size‐Tunable h‐BN Nanosheet Powders

Abstract Bulk availability of 2D material powders presents broad opportunities for various industrial applications. Particle size and morphology control are critical factors that govern their properties, and in particular, large‐scale size‐controlled production of 2D materials nanosheets remains extremely challenging. Herein, a novel 3D template‐catalyzed growth (3D‐TCG) method is demonstrated that allows the mass production of size‐tunable 2D hexagonal boron nitride ( h ‐BN) nanosheet powders, a key material in the 2D materials family. Rather than limiting the nanosheet growth on 2D substrate surfaces, this method provides large numbers of active sites distributed in 3D space, leading to the feasibility of scale‐up production with excellent product homogeneity and high efficiency. Ultrathin h ‐BN nanosheets are synthesized with high throughput (kilogram quantities) and lateral sizes that can be tuned from 100 nm to 10 µm with thicknesses of few layers. Their practical application is demonstrated in lithium metal batteries, where the obtained nanosheet powders are processed and roll‐to‐roll coated on commercial separators (>10 m 2 ). The prototype pouch cell delivers high energy density (501.8 Wh kg −1 ) and improved cycling stability. The template‐based large‐scale production strategy can be used to generically produce various types of bulk pristine 2D nanopowders with potential for many large‐scale applications.