Surface In Situ Compositing of Reactive Liquid‐Metal Anchored 2D Nanomaterial Skins for Active Composite Current Collectors

Surface functionalization through advanced skin-like nanocoating is of great significance due to its tremendous potential in transforming materials technologies. Conventional strategies, including wet-slurry coatings or vapor depositions, not only involve toxic solvents or expensive/time-consuming processes, but also lead to weak interfaces. Here, we discover the compelled wetting effects of liquid-metal (LM) during sponge-rubbing coating, and propose a strategy of surface in situ compositing (SISC) that combines reactive liquid-metal and van der Waals (vdW) materials (e.g., graphene and boron nitride) by sequenced sponge-rubbing. Particularly, the components are in situ composited by the intensive frictional shearing of sponge-rubbing, forming a robust metal-conductive skin-coating with ordered and mechanical interlocking microstructures anchored onto various substrates (e.g., polyimide, PI). For applications, the resultant vdM@PI film has been proven as a high-performance active composite current collector (ACCC) capable of boosting the energy-density and safety of batteries, an advanced Joule-heating material for fast battery thermal-management, and a photothermal material for efficient solar-energy conversion.