Evaluation of nanostructured silicon based anodes with enhanced cycling stability for all solid state lithium batteries

Herein, three representative silicon-based anode materials, namely pure nano-silicon (Si), ball-milled silicon/carbon composite (BM Si/C), and chemical vapor deposition silicon/carbon composite (CVD Si@C), were systematically investigated for their application in all-solid-state lithium batteries. X-ray diffraction and Raman spectroscopy analyses confirmed that BM Si/C maintained the crystalline structure of silicon with a defect-rich carbon network, while CVD Si@C exhibited an amorphous silicon phase uniformly distributed within porous carbon frameworks with Si–C covalent bonding. The initial reversible capacities for Si, BM Si/C and CVD Si@C were 2810.4, 1230.1 and 1648.2 mAh g − 1 , with Coulombic efficiencies of 65.97, 62.81 and 72.94%, respectively. The electrochemical performance of pure Si in this study was limited by capacity decay induced by volume expansion, while BM Si/C demonstrated an “activation-rising” behavior, stabilizing at approximately 900 mAh g − 1 after 100 cycles at 0.5 C. CVD Si@C exhibits outstanding cycling stability. Post-cycling characterizations reveal that despite a remarkable increase in electrode thickness, the surface contours of individual particles remain relatively intact. The porous carbon matrix may partially sustain electrode structural integrity via a combination of inward volume accommodation tendency, confinement effect from Si–C covalent bonds, and stress buffering derived from the amorphous silicon phase to a certain extent. Electrochemical impedance spectroscopy data analysis revealed that BM Si/C possessed the lowest charge transfer resistance, attributed to the three-dimensional conductive network formed by defect-induced carbon, whereas CVD Si@C showed higher resistance yet superior long-term stability. This study provides experimental insights into understanding how different silicon/carbon composite strategies affect the electrochemical performance of ASSLBs.