中文摘要：

以KMnO4和MnSO4为原料，采用水热法制备纳米MnO2，研究了KMnO4浓度对MnO2结构和电容性能的影响。结果表明：KMnO4浓度对 MnO2产物的晶型、晶粒尺寸和形貌影响显著，随着 KMnO4浓度增大，产物晶型由β-MnO2转变为α-MnO2，并且MnO2纤维逐渐增长变粗。晶粒和纤维直径较小的α-MnO2的电荷转移电阻（Rct）和扩散阻抗（W）最小，从而具有最大的电容量和良好的倍率性能，在电流密度为0.05 mA/cm^2时电容量为227F/g；β-MnO2的容量较低，为113F/g，但循环性能最好，经过500次循环后容量保持率达92.0%。

英文摘要：

Nanoparticles ofMnO2 were synthesized by a hydrothermal method using KMnO4 and MnSO4 as raw materials. The influence of KMnO4 concentration on the structure and capacitance properties of MnO2 was investigated. The results show that the KMnO4 concentration has an effect on the crystal type, grain size and morphology of MnO2 sample.β-MnO2 transforms intoα-MnO2, andα-MnO2 nanowires become longer and thicker when the KMnO4 concentration increases. Theα-MnO2 nanowire with the smaller grain size has the minimum charge transfer resistance （Rct） and diffusion impedance （W）, resulting in the maximum capacitance and excellent ratio performance. The maximum capacitance is 227F/g at a current density of 0.05mA/cm^2. Theβ-MnO2 sample has a good cycle performance but a poor capacitance （i.e., 113F/g） and the capacity retention is 92.0% after 500 cycles.