Reconstruction of TiO₂/MnO₂-C nanotube/nanoflake core/shell arrays as high-performance supercapacitor electrodes

Abstract

Construction of electrodes with fast reaction kinetics is of great importance for achieving advanced supercapacitors. Herein we report a facile combined synthetic strategy with atomic layer deposition (ALD) and electrodeposition to rationally fabricate nanotube/nanoflake core/shell arrays. ALD-TiO₂ nanotubes are used as the skeleton core for assembly of electrodeposited MnO₂-C nanoflake shells forming a core/shell structure. Highly porous architecture and good electrical conductivity are combined in this unique core/shell structure, resulting in fast ion/electron transfer. In tests of electrochemical performance, the TiO₂/MnO₂-C core/shell arrays are characterized as cathode for asymmetric supecapacitors and exhibit high specific capacitance (880 F g^-1 at 2.5 A g^-1), excellent rate properties (735 F g^-1 at 30 A g^-1) and good long-term cycling stability (94.3% capacitance retention after 20 000 cycles). The proposed electrode construction strategy is favorable for fabrication of other advanced supercapacitor electrodes.