Modified Chestnut-Like Structure Silicon Carbon Composite as Anode Material for Lithium-Ion Batteries

The chestnut-like structure mesporous silicon sphere@C@void@ nitrogen-doped carbon (MSN@C@void@N-C) composite is designed and prepared successfully by introducing an internal carbon layer as a shell layer on the surface of a mesporous silicon core and then using nickel oxide as template to obtain a cavity between a carbon-coated mesporous silicon core and an external nitrogen-doped carbon layer. The influences of the double carbon layer and cavity on the morphology and electrochemical properties of the composite are systematically investigated by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and galvanostatic charge–discharge tests. The results show that the coordination of the double carbon layer and the middle cavity can not only protect the silicon core from electrolyte corrosion but also improve the electron transmission rate of silicon-based materials as well as provide the space to accommodate the volume expansion of silicon without destruction of the electrode structure. It has been found that the MSN@C@void@N-C composite exhibits excellent electrochemical performance. The first discharge specific capacity is 2499 mAh g–1 and still maintains a discharge specific capacity of 1372 mAh g–1 with a capacity retention rate of 54.9% after 150 cycles. Therefore, the reasonable designs of the structure and morphology for Si/C composites are of great significance for improving the electrochemical performance of silicon-based materials, and this work provides a helpful exploration for development of the next-generation high-energy density lithium-ion batteries.