Ti@δ-MnO2 core-shell nanowire arrays as self-supported electrodes of supercapacitors and Li ion batteries

• Ti@δ-MnO2 core-shell nanowire arrays prepared by a electrochemical method.
• Remarkable rate capability as both Li ion battery and supercapacitor electrodes.
• Good electronic conductivity and facilitated mass transport.

δ-MnO2 is a promissing electrode material of supercapacitors and Li ion batteries (LIBs) owing to its low cost, layer structure and composite valence of Mn. However, the unfavorable electronic conductivity of δ-MnO2 restricts its rate capability in both of the two devices. Herein, a vertically standing Ti nanowire array modified with δ-MnO2 nanoflakes is prepared by a electrodeposition method, and the electrochemical properties of Ti@δ-MnO2 nanowire arrays in supercapacitors and LIBs are investigated. The results show that, the arrays have a capacity of 195 F g−1 at 1.0 A g−1 and can cycle more than 10000 rounds at 10 A g−1 as electrodes of supercapacitors. On the other hand, the arrays behave good rate capability as LIB cathodes, which can release a capacity of 70 mAh g−1 at 10C rate charge/discharge. We suggest that, the good electronic conductivity owing to the core-shell structure and the facilitated mass transport supplied by the array architecture are responsible for the enhanced rate performances in the two devices.