Silicon Nanoparticles Embedded in Chemical-Expanded Graphite through Electrostatic Attraction for High-Performance Lithium-Ion Batteries

Abstract

Silicon (Si) is a promising next-generation anode for high-energy-density lithium-ion batteries. The application of silicon/carbon (Si/C) composites with high Si content is hindered by the huge volume change and insecure electrochemical interface of the Si anode. Herein, chemical-expanded graphite (CEG) is used as a carbon matrix to form Si@CEG/C composites with an embedded structure. CEG with an abundant pore structure and electropositivity can well disperse and accommodate a mass of Si nanoparticles (Si NPs). With the flexibility and porosity of CEG, the embedded structure of Si NPs fixed in an expanded graphite layer can adopt the volume change of Si NPs and offer the abundant path of diffusion of lithium-ion, which leads to a moderate cycle and rate performance. Si@CEG/C exhibits a high reversible capacity of 1232.4 mA h g–1 at a current density of 0.5 A g–1 and with a capacity retention rate of 87% after 200 cycles. This embedded structure of Si/C composites built by CEG is meaningful for the structure design of the Si-based anode with higher specific capacity, active material utilization, and satisfactory cycle stability.

High-performance Si@C anode for lithium-ion batteries enabled by a novel structuring strategy

“…After 10 cycles, however, the R ct values decrease and show no obvious change with increasing cycles, manifesting high conductivity, low interfacial resistance, and stable electrode structure and SEI film. 63,64 In contrast, after 10 cycles, the R ct values of the Si electrode continue to increase with increasing cycles. It indicates that the electrode structure is unstable, and the formed electrode fracture causes the constant generation of new exposed surfaces of active materials, which results in the unstable SEI film to grow continuously, and the electronic and ionic conductive pathways are severely deteriorated.…”

Simple and Safe Synthesis of Yolk-Shell-Structured Silicon/Carbon Composites with Enhanced Electrochemical Properties

“…The phase composition of the composite was further studied through X-ray diffraction (XRD) patterns. As shown in Figure 2 a, all composites exhibit diffraction peaks of crystalline Si at 2θ = 28.5°, 47.7°, 56.2°, 69.2°, and 76.3°, corresponding to the (111), (220), (311), (400), and (331) planes of Si [ 33 ], respectively. In the Si@SnO 2 composite, characteristic peaks of SnO 2 appear at 2θ = 26.5°, 33.8°, and 51.7°, corresponding to the (110), (101), and (211) planes of SnO 2 [ 34 ], respectively, indicating that a layer of SnO 2 is successfully coated on the surface of Si through the annealing process.…”

Constructing Si/6H-SiC Heterostructure As a High-Performance Anode for Boosting Lithium-Ion Storage

“…To deal with the problems caused by volume change, extensive efforts have been devoted to the design of reasonable Si nanostructures, including nanoparticles, , nanowires, , and nanotubes. , It has been revealed that, during the lithiation and delithiation processes, Si particles having a critical size of less than 150 nm will not fracture or pulverize . The fabrication methods of nanostructured Si include chemical vapor deposition, magnesiothermic reduction reaction, , laser ablation, , and ball milling. − Among these methods, ball milling is cost-effective, easy for mass production, and much more possible for commercial application.…”