Structure-preserved 3D porous silicon/reduced graphene oxide materials as anodes for Li-ion batteries

Three dimensional (3D) porous silicon/reduced graphene oxide (Si/rGO) composites with typical networks have suffered damage during electrode preparation, which evidently affects the cycle and rate capabilities of Si/rGO anodes. Here, a controllable evaporation dry method is proposed to fabricate structure-preserved 3D porous Si/rGO anode materials by tuning the pore size distribution of the networks. As a result, after evaporation drying for 3.5 h, the optimal sample of 3D porous Si/rGO anode (denoted as Si–G-3.5) with a pore size of ∼500 nm could preserve its 3D network during the electrode preparation process. While the structures of Si/rGO composites with different drying times (denoted as Si–G-0, Si–G-2.5 and Si–G-4) failed to be preserved. Consequently, The Si–G-3.5 anode exhibits a high reversible specific capacity of 1563 mA h g−1 at 50 mA g−1, 90% capacity retention after 100 cycles and superior rate capability (955 mA h g−1 at 2 A g−1).