Improving the Supercapacitor Performance by Dispersing SiO2 Microspheres in Electrodes

This paper describes a simple, reproducible, and scalable procedure for the preparation of a SiO₂-containing supercapacitor with high cycle stability. A carbon mesoporous material (CMM) with a high specific surface area, CMK-3, was adopted as an electric double-layer capacitor (EDLC) active material for the preparation of electrodes for the supercapacitor. The optimized SiO₂ content decreased as the microsphere diameter decreased, and the optimal specific capacitance was obtained with 6 wt % SiO₂ microspheres (100 nm size). The capacitance improved from 133 to 298 F/g. The corresponding capacitance retention rate after 1000 cycles increased from 68.04 to 91.53%. In addition, the energy density increased from 21.05 to 26.25 Wh/kg with a current density of 1 A/g. Finally, similar results based on active carbon, CeO₂/CMK-3, and graphene/CNT/MnO_v composite electrodes demonstrated that the proposed method exhibits wide compatibility with diverse electrode materials.

Build a Rigid-Flexible Graphene/Silicone Interface by Embedding SiO2 for Adhesive Application

An effective strategy was developed to enhance the adaptability of graphene/silicone matrices under external stimuli by embedding nanoscale SiO2 into the graphene/silicone interfaces as a buffer layer. Chemically reduced graphene (rGE) was first covered by SiO2 using an in situ preparation, forming sandwichlike rGE/SiO2 (rGES). Then, rGES was integrated into methyl vinyl polysiloxane, followed by vulcanization, producing the final rGES/silicone rubber (SR) nanocomposite. Such interfacial modification actually built a rigid-flexible SiO2 buffer layer between rGE and polysiloxane. Obvious improvements were seen in both thermal and mechanical properties due to improved interfacial interaction. In a vulcanized rGES/SR system, the addition of 30 wt % rGES (3 wt % rGE) yielded a tensile strength of 6.13 MPa (up to 25 times that of the unmodified rGE in filled SR), a tear strength of 18.08 kN/m, and an elongation at break of 267%, several times higher than those of an rGE/SR nanocomposite. Thermal analysis results indicated that the initial decomposition temperature of rGES/SR containing 5 wt % rGES (0.5 wt % rGE) increased by more than 98 and 288 °C compared to that of SiO2/SR and rGE/SR, respectively. The rGES/polysiloxane matrices showed a tensile shear adhesive strength of 1.78 MPa when used as an adhesive for aluminum sheets, which is higher than that of the rGE/polysiloxane matrix (0.93 MPa).