3D Bicontinuous Structure of a Pseudocapacitive Ultrathin Shell/Carbon Core: A Novel Electrode for Thin-Film Supercapacitors with High Areal Energy Density

Abstract

Thin-film micro-supercapacitors (MSCs) with high areal capacitance are in great demand due to their wide application in ultra-compact energy storage devices. Carbon electrodes coated with high pseudocapacitance materials have typically been applied, but the increased resistance and pulverization by the pseudocapacitive materials still require improvement. To tackle this issue, we present a 3D bicontinuous structure of the pseudocapacitive shell and carbon core. Specifically, the 3D carbon structure is fabricated using multibeam interference lithography, and conformal thin layers of MnO2 or polyaniline (PANI) are obtained by electrodeposition. This electrode maintains a monolithic carbon conductive structure, even with a pseudocapacitance material coating. The conformal pseudocapacitive shell exhibits low resistance and structural integrity in redox reactions. MnO2– or PANI–carbon electrode MSCs achieve areal capacitance of 4.93 or 26.4 mF cm–2, respectively. The highest areal energy density of 3.67 μW h cm–2 is obtained for the PANI–carbon electrode MSC. This value is superior to the values achieved in recent thin-film MSCs, which demonstrates the advantages of 3D bicontinuous structures.