A Tremella-Like Nanostructure of Silicon@void@graphene-Like Nanosheets Composite as an Anode for Lithium-Ion Batteries

Abstract

Graphene coating is receiving discernable attention to overcome the significant challenges associated with large volume changes and poor conductivity of silicon nanoparticles as anodes for lithium-ion batteries. In this work, a tremella-like nanostructure of silicon@void@graphene-like nanosheets (Si@void@G) composite was successfully synthesized and employed as a high-performance anode material with high capacity, cycling stability, and rate capacity. The Si nanoparticles were first coated with a sacrificial SiO2 layer; then, the nitrogen-doped (N-doped) graphene-like nanosheets were formed on the surface of Si@SiO2 through a one-step carbon-thermal method, and the SiO2 layer was removed subsequently to obtain the Si@void@G composite. The performance improvement is mainly attributed to the good conductivity of N-doped graphene-like nanosheets and the unique design of tremella nanostructure, which provides a void space to allow for the Si nanoparticles expanding upon lithiation. The resulting electrode delivers a capacity of 1497.3 mAh g−1 at the current density of 0.2 A g−1 after 100 cycles.

Lithiation Behavior of Coaxial Hollow Nanocables of Carbon–Silicon Composite

“…Because of the low Young’s moduli (0–3 GPa), SEI cannot endure the large volume variation of silicon, thus continuous cracks and reconstructs due to the exposure of silicon with electrolyte . The excessive growth of SEI consumes electrolyte and Li sources, leading to low Coulombic efficiency and capacity fading in real batteries. , Some strategies have been proposed to improve the Coulombic efficiency of silicon anodes, such as anode prelithiation , and isolation of silicon from electrolyte with a coating layer. − However, it is still difficult to enhance the Coulombic efficiency up to 99.9%.…”

Decreasing Deformation and Heat as Well as Intensifying Ionic Transport of Si Using a Negative Thermal Expansion Ceramic with High Ionic Conductivity

“…One is to design various morphologies, including nanospheres, nanowires, nanofilms, nanotubes, , and porous silicon, to mitigate bulk effects and reduce structural collapse . Another is to form silicon composites with other materials such as amorphous carbon, various graphites (natural graphite, expanded graphite, and graphene), − conductive polymers, Metal-organic frameworks (MOFs), Mxene, metals (Ag, Al, Cu, and Sn), and oxides (TiO 2 , SiO x , and Al 2 O 3 ) to buffer volume change or improve electrical conductivity. However, most of these methods only consider the volumetric effects and electrical conductivity of silicon and ignore the heat damage and deformation, which will bring disadvantages such as structural degradation, internal stress, deteriorating interface, and undesirable side reactions.…”

Dual Carbonaceous Materials Synergetic Protection Silicon as a High-Performance Free-Standing Anode for Lithium-Ion Battery

“…On the other hand, the carbon second phase can also function as a protective barrier to prevent direct exposure of silicon in the electrolyte and thus enhance the interface stability of the electrode. Accordingly, various research works have been recently reported on Si-based anodes, such as core-shell Si@C composites [24], hollow Si/C nanoparticle [25,26,27], Si/C nanofibers [28,29,30,31,32], Si/Graphene nanosheets [33,34,35,36,37], etc. Some fabrication methods are facile and can realize improvements for the electrochemical performance of Si anode.…”