Interface engineering with Au nanoparticles for stable and high-capacity Si thin-film anodes

Silicon (Si) is a promising anode material for next-generation lithium-ion batteries owing to its high theoretical capacity; however, its large volume changes during lithiation and delithiation lead to interfacial delamination and rapid capacity fading. Here, we demonstrate that inserting Au nanoparticles (NPs) between Si and a Ta substrate effectively enhances the adhesion and electrochemical stability of Si thin-film anodes. The sample with uniformly distributed Au nanoparticles (∼10 nm) exhibited the best performance, maintaining a discharge capacity of ∼2360 mAh g−1 after 100 cycles at 1 C (about 70% of its initial capacity). Electron microscopy analyses revealed that the Au NPs acted as mechanical anchors at the Si/Ta interface, preventing delamination and preserving electrical contact during repeated cycling. These results highlight that nanoscale interface engineering using Au NPs is a simple and effective approach to achieve durable, high-capacity Si thin-film anodes for advanced lithium-ion batteries.