Enhanced Electrolyte Ion Penetration in Microdome-like Graphene with High Mass Loading for High-Performance Flexible Supercapacitors

Achieving an excellent electrochemical performance of graphene electrodes with high mass loading is challenging to graphene-based supercapacitors. Generally, the high mass loading of graphene usually results in drastic restacking/aggregation, which further significantly deteriorates the penetration of electrolyte ions. Herein, we attempted to synthesize a kind of microdome-like graphene by CVD on unique natural coral templates. More importantly, these microdome-like graphene materials are able to support the axle and absorb shock from the compression, effectively preventing the aggregations of graphene in the compressed free-standing electrodes for enhancing the electrolyte ion penetration. Additionally, according to Trasatti's theory, the non-diffusion-controlled capacitive process is primary even at a high areal mass loading of 20.2 mg/cm(2), which is caused by more electrolyte ions accessible surfaces in the compressed electrode. Therefore, this unique microdome-like graphene leads to robust electrolyte ion penetration and electron conduction, endowing the compressed electrodes with approved electrochemical properties. This superior performance is evidenced by satisfying the specific capacitance, energy density, and power density of 293 F/g, 63.6 Wh/kg, and 1261 W/kg at 2 A/g, respectively. Meanwhile, a symmetric supercapacitor assembled by gel PVA/H3PO4 electrolyte delivers excellent compressible function and flexibility, achieving a high areal energy density (7.34 mWh/cm(2)) and the impressive cyclic stability of 96.5% after 10000 cycles at a bending angle of similar to 180 degrees. This structural design of microdome-like graphene will open up opportunities in the fundamental understanding and practical applications in the field of graphene-based flexible energy devices.