Vertically aligned Si@reduced graphene oxide frameworks for binder‐free high‐areal‐capacity Li‐ion battery anodes

Summary In this study, lamellar‐structured, vertically aligned silicon@reduced graphene oxide frameworks (VA‐Si@rGO) are developed for binder‐free, high‐areal‐capacity lithium ion battery (LiB) anodes. First, SiO 2 /rGO frameworks with unidirectional pores are constructed via the gelation of SiO 2 /graphene oxide sol and subsequent freeze‐casting. Afterwards, the sturdy constructed frameworks are maintained during a series of processes, namely magnesiothermic reduction, acid etching, and thermal carbon coating, which result in carbon‐coated VA‐Si@rGO. The electrode exhibits a high specific capacity, reversibility, and cycle stability, which are attributed to its unique inner porous structure, high Si yield, and uniform carbon layers. A high areal capacity of approximately 9 mAh cm −2 could be achieved by increasing the initial sol concentration up to 23.5 wt%. Furthermore, even at a high current density of 3 mA cm −2 , the electrode delivered a high areal capacity of approximately 6 mAh cm −2 and exhibited excellent stability with a high capacity retention of 68% after the 150th cycle.