Investigating the structure, microstructure, an‎d electrochemical performance of silicon-carbon composites as lithium-ion battery anodes

3/21/2026 12:00:00 AM

Silicon-based anodes are considered among the most promising anode materials for lithium-ion batteries due to their high theoretical capacity (approximately 4200 mAh g⁻¹). However, severe challenges such as large volume expansion (about 400%), poor electrical conductivity, an‎d unstable solid–electrolyte interphase (SEI) significantly hinder their practical application. The aim of this study is to investigate the synergistic effect of conductive copper additives an‎d carbon-based materials, including graphene oxide an‎d carbon nanowebs, on the electrochemical performance an‎d structural stability of silicon anodes. Silicon–copper composites were synthesized via an electroless deposition an‎d chemical reduction method in a wet environment, while ternary silicon–copper–carbon composites were prepared using a simple mechanical ball-milling process. Among the prepared samples, the ternary silicon–copper–reduced graphene oxide composite (Si@Cu@rGO) exhibited the best electrochemical performance. In this structure, silicon nanoparticles are encapsulated within a conductive copper shell an‎d anchored onto a reduced graphene oxide (rGO) framework. This architecture effectively mitigates the severe mechanical strain induced by silicon volume expansion, thereby maintaining the structural stability of the anode during repeated charge–discharge cycles. The microstructure of the samples was characterized using field-emission scanning electron microscopy (FESEM) an‎d transmission electron microscopy (TEM), revealing a homogeneous distribution an‎d effective confinement of Si@Cu nanoparticles within the rGO sheets. Energy-dispersive X-ray spectroscopy (EDS) elemental mapping further confirmed the uniform distribution of Si, Cu, an‎d C elements throughout the composite. The presence of crystalline phases corresponding to these elements was identified by X-ray diffraction (XRD). X-ray photoelectron spectroscopy (XPS) analysis detected the characteristic Si 2p, C 1s, an‎d Cu 2p spectra. Raman spectroscopy revealed distinct silicon peaks along with the D an‎d G ban‎ds, indicating a high density of defects within the composite structure. Nitrogen adsorption–desorption analysis demonstrated a mesoporous structure with a high specific surface area. Electrochemical eva‎luation of the optimized Si@Cu@rGO anode indicated that the incorporation of copper an‎d carbon materials significantly enhances electrical conductivity an‎d structural stability, effectively suppressing capacity fading during long-term cycling. Electrochemical impedance spectroscopy (EIS) results showed a substantial improvement in electrical conductivity, with the charge-transfer resistance decreasing from 69.32 Ω before cycling to 6.07 Ω after the first cycle. The Si@Cu@rGO anode delivered a high reversible capacity of 960 mAh g⁻¹ at a current density of 1 A g⁻¹ after 200 cycles. Moreover, the electrode exhibited a high initial coulombic efficiency of 80.35% an‎d excellent rate capability, delivering specific discharge capacities of 3919.73 mAh g⁻¹ an‎d 1963.06 mAh g⁻¹ at current densities of 0.05 A g⁻¹ an‎d 1 A g⁻¹, respectively (based on the total mass of the electrode).

باتري ليتيوم-يون - آند - كامپوزيت‌هاي سيليكون - افزودني رسانا - مواد كربني

Lithium-ion battery; Anode; Silicon-based composite; Conductive additives; Carbon materials

Helia Mahdavi Adeli

Dr. Masood Hasheminiasari - Dr. Somaye Alamolhoda