– shell composite microtube arrays for high-performance lithium ion batteries †

Tubular array structures are very attractive for electrochemical energy storage and conversion systems due to their unique physicochemical properties. Herein, a NiO microtube array is fabricated via a facile oxalic acid corrosion method followed by heat treatment. A NiO@MnO2 core–shell composite microtube array is further achieved by the anodic electrodeposition using the NiO microtube array as substrate. When applied as self-supported electrode for lithium ion batteries (LIBs), the NiO@MnO2 core–shell composite microtube array electrode shows excellent lithium storage properties. The electrode delivers a reversible capacity of 510 mA h g 1 at a high rate of 5.1 A g , showing its good rate capability. In particular, a reversible capacity of 1573 mA h g 1 is observed after 500 cycles at a current density of 0.53 A g , demonstrating the superior cycling performance of the electrode. The electrodeposited MnO2 layer as a protective shell prevents the NiO microtubes from deformation during electrochemical cycling, responsible for the superior cycle stability of the NiO@MnO2 core–shell composite microtube array electrode. The prominent lithium storage performance of the composite microtube array electrode can be attributed to its unique structure characteristics.