3D nanotube-structured Ni@MnO2 electrodes: Toward enhanced areal capacitance of planar supercapacitors

Rationally engineering three dimensional (3D) architrctures of transition-metal oxides (TMOs) is of great concern for the effective enhancement of electrochemical capacity, nevertheless, it is still challenging to selectively construct well-defined 3D architectured electrode materials in planar-configuration supercapacitors (SCs). Herein, we demonstrated a novel 3D nanotube-structured Ni@MnO2 electrode with interdigital configuration for high-performance planar supercapacitors. By combining transfer printing, alloying-dealloying and electrodeposition methods, 3D architecture of nanotube-structured Ni@MnO2 was subtly built on flexible Kapton substrate. The highly conductive Ni nanotubes embedded in MnO2 nanoflakes offer efficient electron collection paths, endowing the 3D electrodes with low internal resistance. Simultaneously, this 3D nanotube architecture provides multiple channels for electrolyte penetration and large active surface for Faradaic reactions. For these reasons, 3D SCs deliver remarkably enhanced areal capacitance of 10.75 mF cm−2, 2.4 times of the pristine SCs without 3D architecture. Moreover, 3D SCs exhibit desirable flexibility under different bending conditions, which indicates the potential feasibility of planar-configuration SCs as energy-storage components for wearable electronics.