# Scalable Fabrication of Si-Graphene Composite as Anode for Li-ion Batteries
###### Abstract
[PERSON]'s group synthesized a porous 3D graphene hydrogel (GH) composite embedded with an ultrathin SiO\({}_{x}\) layer coated Si nanoparticles. The fabricated composite (Si@SiO\({}_{x}\)/GH) showed remarkable storage capacity and good capacity retention of 80% at 140 th cycle [24]. Graphene and reduced graphene oxide (rGO) have been extensively investigated to synthesize composite anode materials in various ways to explore better electrochemical performance [25; 26; 27; 28]. Due to the large specific area and great mechanical flexibility, it was reported that rGO not only provided a porous graphene-like structure for compromising the volume change of Si and maintaining the structure of the anode materials but also served as a binder that can form chemical bonds with OH functionalized Si nanoparticles [10; 25; 29]. Instead of simply wrapping rGO around the Si nanoparticles by physical mixing, which usually leads to failure of stable cycling performance despite the good contact between Si and rGO, researchers have designed to introduce a second carbon phase such as amorphous carbon to achieve better cycling performance of Si anode materials [30; 31]. [PERSON] et al. presented a freeze-drying method, followed by a subsequent chemical vapor deposition (CVD) to synthesize the Si-rGO-C composite, which created a conductive network to maintain the contact between the current collector and the electrode [31; 32]. Another alternative method to prepare Si/rGO composite anode material is the in situ reduction or decomposition of Si precursors such as silicon dioxide (SiO\({}_{2}\)), preventing Si nanoparticles from agglomerating [33]. [PERSON] et al. presented a step-by-step synthesis of fabricating Si-loaded 3D graphene composite by in situ magnesium reduction of SiO\({}_{2}\)@Graphene [34]. The produced Si@Graphene composite yielded a superior specific capacity of 500 mAh g\({}^{-1}\) at a current density of 20 A g\({}^{-1}\). [PERSON]'s group designed a porous Si nanofilm growing on both sides of rGO sheets by in situ reduction of SiO\({}_{2}\)-rGO-SiO\({}_{2}\). The resultant Si-rGO-Si composite was then coated by a carbon layer, forming a stable solid electrolyte interface (SEI). The electrode made of this carbon-coated Si composite showed a remarkable specific capacity of 894 mAh g\({}^{-1}\) after 1000 cycles at 1 A g\({}^{-1}\)[35]. However, the reported approaches of fabricating Si/graphene electrode require either multistep synthesis or complex surface modification, despite the enhanced capacity performance that has been achieved [30; 31; 34]. It is essential to develop an efficient and cost-effective route of fabricating Si/graphene compound to meet the needs of potential commercialization. In this article, we report a simple and scalable method of fabricating Si-graphene nanocomposite as an anode material for LIB by uniformly dispersing Si and graphene nanoparticles in liquid media with the aid of an appropriate surfactant. The idea was prompted from our previous research in the field of nanofluids, where we developed novel \"nanosolids\" through the use of surfactants in aqueous media [36; 37; 38]. In this work, the assistance of the surfactant results in the homogeneous distribution of graphene nanosheets with Si nanoparticles firmly attached to them, that significantly enhances the cross-layer electron transportation and compromises the volume expansion of Si nanoparticles during the lithiation/delithiation process. Besides, the graphene nanosheets provide an efficient path for the Li ions, which is essential for high capacity and cycling performance [23]. This fabrication approach is cost-effective and easy to scale up compared to known techniques, making it a promising candidate for commercializing Si anode materials for LIBs [39].