Self-adaptive anode design with graphene-coated SiOx/graphite for high-energy Li-ion batteries

Si-based materials are promising high-capacity anodes, which can improve the energy density of Li-ion batteries (LIBs) that are required for the advancement of electric vehicles. Nevertheless, the severe volume change of Si-based materials during repeated cycles limits their widespread applications in LIBs. Here, we report a durable and high-energy blended anode composed of artificial graphite (AG) and graphene (Gr)-coated SiOx (SiOx@Gr) particles. The Gr coating reduces the electrode swelling during repeated cycles and increases the initial Coulombic efficiency of SiOx. This further increases the areal capacity owing to the reduction of carbon black (CB) content to 3 wt%. The SiOx@Gr/AG blended anode exhibits excellent properties compared to the bare SiOx/AG anode. These results can be attributed to the self-adaptive behavior by Gr sheets coated on SiOx particles, which mitigates the mechanical damage on the AG particles and maintains the electron conduction pathways. Hence, the reversibility of the charge–discharge reactions improves, as revealed by Raman spectral mapping and powder flowability measurements. Furthermore, the full-cell with the SiOx@Gr/AG anode exhibits good cycling stability and high volumetric capacities over 300 cycles compared to the full-cell with the bare SiOx/AG anode and AG-only anode, demonstrating the applicability of the high-capacity Si-based anodes for LIBs.