Scalable, Multifunctional Nanosilicon Composite Protective Interlayer to Suppress the Formation of Lithium Dendrites for Stabilizing Lithium Metal Anodes

Lithium metal batteries are a promising route to overcome the energy-density ceiling of the conventional lithium-ion systems. Nevertheless, their commercialization remains hindered by Li dendrite formation, an unstable solid–electrolyte interphase, and increased internal resistance. To address these challenges in a scalable manner, we report a roll-to-roll compatible strategy to fabricate a Si-based composite film as an artificial protective interlayer. The film is produced through a simple slurry-casting method. The protective interlayer is composed of Si-nanoparticles, PVDF-HFP, and Super C45. During activation, this layer evolves into a flexible mixed ionic-electronic conductive interlayer with a fine porous structure. These chemical and structural features homogenize Li⁺ flux while providing continuous and uniform ionic/electronic pathways. Electrochemical characterization demonstrates the effectiveness of the interlayer. In symmetric cells, it enables stable Li plating/stripping for over 250 h at 1 mA/cm². It also significantly lowers nucleation overpotential (from 157 to 18 mV), increases exchange current density, and reduces voltage hysteresis. These results signify enhanced electrochemical kinetics, which in turn directly lowers the interfacial resistance during the Li growth process. Consequently, ex situ microscopy confirmed a stable and uniform Li deposition morphology, highlighting its capability to stabilize the lithium metal anode for high-performance batteries.