The experimental capacitance of manganese oxide (MnO₂) is ordinarily less than 100 F/g due to their poor electronic conductivity and low structural stability. Herein, we demonstrate the design and synthesis of doped δ-MnO₂ with enhanced electronic conductivity by the introduction of transitional metal Fe, Co and Ni. Structural characterizations shown that the Raman spectra of doped MnO₂ has obviously blue shifted, as well as the separation values of Mn 3s XPS spectra has expanded, which indicate the transitional metal doping successfully changes the crystal lattice of δ-MnO₂. The I-V measurements confirm that the electronic conductivity of MnO₂ is significantly improved after doping. As a result, the Fe doped δ-MnO₂ with a 0.5% doping amount displays the highest specific capacitance of 157 F/g at 0.5 A/g, by increasing 50.4% of the specific capacity than non-doped MnO₂. Simultaneously, the Co doped δ-MnO₂ exhibits the superb cycling stability (almost no degradation). Furthermore, the assembled 0.5% FeMO//AC, 1% CoMO//AC and 1% NiMO//AC asymmetric supercapacitor provide a specific energy densities of 30.3, 25.2 and 23.6 Wh/kg at a power density of 1000 Wh/kg. The excellent properties of as-prepared MnO₂ are due to the enhanced conductivity after doping, which can ascribed to the forming of intermediate bands, or changing the intensity of valence band/conduction band as demonstrated by spin-polarized density functional (DFT) calculations. Thus, the current work will provide a pathway for the development of high-performance pseudocapacitive materials, as well as for other energy storage systems.

氧化锰（MnO ₂）的实验电容由于其差的电子电导率和低的结构稳定性而通常小于100 F / g。这里，我们证明了设计和δ掺杂的MnO合成₂通过引入过渡金属Fe，Co和Ni中具有增强的电子传导性。所示结构表征该掺杂的MnO的拉曼光谱中₂具有明显的蓝移，以及分离值的Mn 3S XPS谱扩大，这表明过渡金属掺杂成功地改变δ-的MnO的晶格₂。IV测量证实MnO ₂的电子电导率掺杂后显着改善。其结果是，Fe的δ掺杂的MnO ₂用0.5％掺杂量的显示器157的F / G的最高比电容为0.5 A /克，通过增加比的比容量的50.4％的非掺杂的MnO ₂。同时，将Coδ掺杂的MnO _2所表现出高超的循环稳定性（几乎无降解）。此外，组装的0.5％FeMO // AC，1％CoMO // AC和1％NiMO // AC不对称超级电容器在功率密度为1000 Wh / kg时提供的比能量密度分别为30.3、25.2和23.6 Wh / kg。制备的MnO ₂的优异性能这是由于掺杂后电导率的提高，这可以归因于中间带的形成，或由于自旋极化密度泛函（DFT）计算所证明的价带/导带强度的改变。因此，当前的工作将为高性能伪电容材料以及其他储能系统的开发提供一条途径。