Enhanced electrochemical performance of Sn-doped MnO2 and study on morphology evolution

In this work, Sn-doped MnO2 samples have been synthesized by a simple hydrothermal method with the aim to enhance the electrochemical performance. With increase of Sn amount, the morphology of Sn-doped MnO2 changes from sheets composed flower-like nanostructures to rod-like nanostructures. The specific capacitance of Sn-doped MnO2 nano-flowers reaches 243.6 F g(-1) at 1 A g(-1). For comparison, the specific capacitance of pure MnO2 nano-flowers is only 148.6 F g(-1), which clearly demonstrates the enhancement in electrochemical activity of MnO2 by Sn doping. The Sn-doped MnO2 nano-flowers also exhibit a relative good cycling performance with 95% capacitance retention after 10000 cycles test. During cycling test, the Sn-doped MnO2 nano-flowers undergo a morphology transformation from nanoflowers to rod-like nanostructures. This would reduce the specific surface area, which might be the reason causing the capacitance decay. Our findings suggest that Sn doping exhibit a controlling effect on the morphology of MnO2, which shows the tendency to form rod-like during synthesis process and cycling test. This work may provide clues for the improvement of MnO2 electrochemical performance by Sn doping. (c) 2019 Published by Elsevier B.V.