Synthesis and electrochemical performance of β-MnO2 with semi-tubular morphology

β-MnO2 with semi-tubular morphology has been prepared in a mixed solution of KMnO4 and MnCl2 by a facile hydrothermal route without using templates, catalysts, and organic reagents. The structure of the obtained β-MnO2 is systematically investigated by XRD, SEM, and TEM. Results show that the as-prepared β-MnO2 has novel semi-tubular morphology, and its particle shows a diameter of 300–400 nm and length up to 1–4 μm. The prepared β-MnO2 shows a good electrochemical performance, and delivers a discharge capacity of 195 mAh g−1 after 40 cycles between voltage limit of 1.5 and 4.5 V at a constant current density of 20 mA g−1.