Ultrathin Amorphous Boron Nitride Films and Their Functional Integration in Lithium Metal Anodes

Ultrathin amorphous materials are promising counterparts to 2D crystalline materials, yet their properties and functionalities remain poorly understood. Amorphous boron nitride (aBN) has attracted attention for its ultralow dielectric constant and superior manufacturability compared with hexagonal boron nitride. Here, we demonstrate wafer-scale growth of ultrathin aBN films with exceptional thickness and composition uniformity using capacitively coupled plasma-chemical vapor deposition (CCP-CVD) at 400 °C. Beyond dielectric applications, we reveal an unexpected functionality─serving as an interfacial layer in Li anode current collectors to improve Li plating/stripping reversibility by suppressing dendrite formation and corrosion. aBN-modified Cu current collectors deliver superior cycling stability and capacity retention in large-format Li-S battery pouch cells, with a capacity decay of 0.062% per cycle at N/P = 1.3, seven times lower than that of pristine Cu (0.44%). These findings establish aBN as a scalable, high-performance interfacial material for lithium metal anodes in next-generation energy storage technologies.