Spatial-Interleaving Graphene Supercapacitor with High Area Energy Density and Mechanical Flexibility.

Abstract

The booming portable electronics market has raised huge demands for the development of supercapacitors with mechanical flexibility and high power density in the finite area; however, this is still unsatisfied by the currently thickness-confined sandwich design or the in-plane interdigital configuration with limited mechanical features. Here, a spatial-interleaving supercapacitor (SI-SC) is first designed and constructed, in which the graphene microelectrodes are reversely stacked layer by layer within a three-dimensional (3D) space. Because each microelectrode matches well with four counter microelectrodes and all 3D spatial-interleaving microelectrodes have narrow interspaces that maintain the efficient ions transport in the whole device, this SI-SC has a prominent liner capacitance increase along with the device thickness. As a result, the high specific areal capacitance of 36.46 mF cm^-2 and 5.34 μWh cm^-2 energy density is achieved on the 100 μm thick device. Especially, the microelectrodes in each layer are interdigitated, ensuring the outstanding mechanical flexibility of SI-SC, with ∼98.7% performance retention after 10⁴ cycles of bending tests, realizing the excellent integration of high area energy density and mechanical flexibility in the finite area. Furthermore, the SI-SC units can be easily integrated into wearable electronics to power wristwatches, light-emitting diodes (LEDs), calculators, and so on for practical applications.