# Scalable Fabrication of Si-Graphene Composite as Anode for Li-ion Batteries
###### Abstract  
A facile and scalable method is reported to fabricate Si-graphene nanocomposite as anode material for Li-ion batteries (LIBs) with high capacity and capacity retention performance. The Si-graphene electrode showed an initial discharge capacity of 1307 mAh g\({}^{-1}\) at a current rate of 0.1C. At the 25 th cycle, the electrode retained a discharge capacity of 1270 mAh g\({}^{-1}\), with an excellent capacity retention of 97%. At the 50 th cycle, the electrode still retained high capacity retention of 89%. The improved capacity retention of Si-graphene anode compared with Si anode is attributed to the mechanical flexibility of graphene that compromises the volume expansion of Si during the lithiation/delithiation process. The electrochemical impedance measurement further confirms the enhanced electrical conductivity and the denser solid-electrolyte-interface of the Si-graphene electrode. This fabrication approach is cost-effective and easy to scale up compared to known techniques, making it a promising candidate for commercializing Si-based anode for LIBs. S +
Footnote †: journal: Applied  
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Footnote 1: email: {deng.lou,deng. explored to overcome Si anode materials' critical volume change issue to meet satisfactory cycling performance [12]. Graphene is a promising material to improve the electrochemical performance of Si anode because of its high electrical conductivity and 2D layered structure that can solve the problem of the significant volume change of Si [13; 14]. Specific structures of Si/Graphene have been explored, such as core-shell structure and Si/graphene foil structure [13; 15; 16]. The freestanding Li\({}_{x}\)Si/graphene reported by [PERSON] et al. with a unique foil structure, where graphene sheets entirely encapsulated Li\({}_{x}\)Si nanoparticles were stable in different air conditions and yielded 98% capacity retention after 400 cycles [15]. The silver-coated Si/graphene core/shell fiber structure fabricated by wet-spinning showed significantly improved electrochemical performance due to the structural integrity of double-locked graphene layers [17]. Recently, [PERSON] et al. synthesized Si/graphene composite through ball-milling technique. The Si nanoparticles and the graphene nanosheets were firstly functionalized with amino and carboxyl groups, respectively, in order to obtain covalent interactions, followed by a ball-milling process where the functionalized Si and graphene self-assembled. The as-prepared composite exhibited stable cycling performance after 500 cycles due to the graphene sheets successfully encapsulated Si nanoparticles on their surfaces. The reported synthesis route has the potential to be scaled up and extended to fabricate Si anode for commercialization of LIB electrodes [18]. However, the challenge arises as graphene easily forms agglomerates due to the high van der Waals interactions [19]. One of the common ways to overcome such a challenge is to apply a binder between the graphene sheets. The Si/Nitrogen(N)-doped graphene pomegranate-like structure constructed by Si nanoparticles surrounded by N-doped graphene sheets was successfully synthesized and showed remarkable capacity retention [20; 21]. Sulfur (S) has also been used to dope the graphene sheets, as reported by [PERSON] et al., who introduced a new design of wrapping Si nanoparticles with S-doped graphene sheets and then shielding the Si/S-doped graphene composite with polyacrylamide(PAN) [22]. [PERSON] et al. modified Si nanoparticles with a thin polyaniline layer and obtained well-dispersed Si into graphene sheets using supercritical carbon dioxide (s\(\mathrm{cCO_{2}}\)). The fabricated composite showed superior capacity performance which was attributed to the graphene sheets and the polyaniline shell that was polymerized on the Si nanoparticles. the synthesized graphene-polyaniline-Si framework provided excess space to tolerate the volume change of Si and in the meantime promote the diffusion of Li ions [23].