Graphene-coated Si/C composites for high-density electrodes: Mitigating silicon degradation and enhancing cycle life in lithium-ion batteries

Abstract

Silicon, which serves as the anode active material in lithium-ion batteries (LIBs) because of its high capacity, suffers from performance degradation during continuous cycling. In this study, we designed a high-energy density electrode using artificial graphite (AG) with a graphene-coated Si/C active material (Gr@Si/C). The Gr@Si/C composite synthesized via iterative coating processes not only ensures the electronic conductivity of adjacent silicon particles but also provides a buffering capability against volumetric expansion during repeated charge/discharge cycles at high loading and increased electrode density. Remarkably, the prepared Gr@Si/C‒AG blended electrode exhibited enhanced cycle life characteristics compared with those reported in previous studies. X-ray diffraction analysis confirmed the establishment of an electron conduction path and revealed the effect of impeding particle isolation from the conducting network. Furthermore, full cells incorporating the Gr@Si/C‒AG composite electrode harmonized with the cathode exhibited superior capacity retention of more than 70 % over 200 cycles. These findings suggest that graphene-coated Si/C composites are promising anode active materials for LIBs.