Microstructure and supercapacitive properties of buserite-type manganese oxide with a large basal spacing

► Mg-buserite with a large basal spacing of 10 Å was successfully synthesized. ► Mg2+ and two sheets of H2O molecules occupy the interlayer region of Mg-buserite. ► The maximum specific capacitance of Mg-buserite is 164 F g−1 at 1 mV s−1. ► The specific capacitance of Mg-buserite decreased only 6% after 22,000 cycles. ► The superior capacitive behaviors are attributed to the large basal spacing.