One-Step Core-Shell Structuring of Silicon Graphene Composite Anode Materials by Aqueous Reduced Graphene Oxide: Toward Practical Use of High-Performance Lithium-Ion Battery

Carbon coatings for silicon (Si)-based anode materials are essential for designing high-performance Li-ion batteries (LIBs). The coatings prevent direct contact with the electrolyte and enhance anode performance. However, conventional carbon coatings are limited by their volume expansion and structural degradation, which lead to capacity fading and reduced durability. This study introduces a scalable and practical one-step carbon-coating strategy for directly coating silicon suboxide (SiO_x)-based materials using aqueous quasi-defect-free reduced graphene oxide (QrGO) without post-treatment, unlike conventional graphene oxide (GO)-based coating methods. This simple process enables uniform encapsulation with QrGO for a highly adhesive and conductive coating. The QrGO-based composite anode material has several advantages, including reduced cracking due to volume expansion and enhanced charge carrier transport, as well as an increased Si content of 20 wt.% compared to the 5 wt.% in typical commercial Si-based active materials. In particular, the capacity retention of the QrGO-coated Si electrodes dramatically increases at high C-rate. The full cell exhibited long-term stability and capacity that were twice that of commercial SiO_x-based cells. Therefore, the QrGO-based one-step coating process represents a scalable, transformative, and commercially viable strategy for developing high-performance LIBs.