Improved Electrochemical Performances of Graphene Hybrids Embedded with Silica as the Functional Connection Layer for Supercapacitors

•A hierarchical SiO2/graphene/polyaniline porous electrode material is fabricated via simple cross-dimensional assembling strategy.•Embeded SiO2 facilitated the porosity of electrodes and further promoted the wettability of graphene with electrolyte.•SiO2 is a low cost, easily available and green alternative for conventional metallic oxides.•Improved specific capacitance, cycling life and energy density are obtained. Graphene, conducting polymers and their hybrids have more superiority and potential as electrode materials for supercapacitors. Neverthless, graphene encountered challenges to guarantee adequate interactions with conducting polymers while maintaining a high level of naked surface for the permeability with electrolytes. To tackle this challenge, developing functionalized or new structured graphene hybrids and their controllable preparation novel strategy is urgent and a focus strategy. Here, SiO2/graphene/polyaniline (SGP) is fabricated through the cross-dimensional assembling of two-dimensional graphene with zero-dimensional SiO2 and polyaniline successively. SiO2 is chosen as a functional connection layer between electrodes and electrolytes, and between hydrophobic graphene and polyaniline for aqueous supercapacitors. Hydrophilic SiO2 not only enhanced the interfacial interactions and ion exchanges at the electrolyte/electrode interface, but also suppressed the stacking between graphene and polyaniline, and among graphene layers. As a result, both the electric double layer capacitance of graphene and pseudocapacitance of polyaniline are better utilized with the aid of SiO2. SGP shows a capacitance retention of 90% after 3500 cycles and improved electrochemical performances, higher than graphene/polyaniline based on both three-electrode and two-electrode cell configurations. These findings demonstrate that SiO2 embeded graphene hybrids is an effective strategy to promote the overall electrochemical properties for supercapacitors.