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<p>Al-doped manganese dioxide (MnO<sub>2</sub>) was synthesized by simple hydrothermal method, and a controllable phase transition of the MnO<sub>2</sub> crystal phase from <i>β</i> to <i>δ</i> was achieved. The effects of Al doping concentration on the structure and electrochemical properties of electrode materials were studied in detail. The results show that the controlled synthesis requires a synergy between KMnO<sub>4</sub>, MnCl<sub>2</sub> and AlCl<sub>3</sub>, and that Al<sup>3+</sup> plays an important role. Compared with the pure phase MnO<sub>2</sub>, the crystallinity of Al-doped MnO<sub>2</sub> decreases and the specific surface area increases, which provides more active sites for the electrode material. When 3 mmol Al<sup>3+</sup> is added, the prepared MnO<sub>2</sub>-3 has the largest specific capacitance and the highest rate performance. The energy density of the asymmetric supercapacitor (ASC) with MnO<sub>2</sub>-3 as the positive electrode and activated carbon (AC) as the negative electrode can reach 18.4 W·h/kg at the power density of 400 W/kg, and the capacity can maintain 90% of the initial value after 20000 cycles, indicating that Al-doped MnO<sub>2</sub> has certain practical application value. This study provides favorable guidance for MnO<sub>2</sub> as a high performance electrode material.</p>

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Controllable phase transition of Al3+ induced manganese dioxide from β- to δ-type and their Al-doped δ-type manganese dioxide for high-performance asymmetric supercapacitors

  • 期刊论文

  • 发表日期：

    2025年6月1日

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  • Xiao-yang Cheng,
  • Li-hua Zhang,
  • Ling-yan Li,
  • Hao Wu,
  • Jin-feng Zheng,
  • Jia-rong Yao,
  • Gui-fang Li

摘要

Al-doped manganese dioxide (MnO2) was synthesized by simple hydrothermal method, and a controllable phase transition of the MnO2 crystal phase from β to δ was achieved. The effects of Al doping concentration on the structure and electrochemical properties of electrode materials were studied in detail. The results show that the controlled synthesis requires a synergy between KMnO4, MnCl2 and AlCl3, and that Al3+ plays an important role. Compared with the pure phase MnO2, the crystallinity of Al-doped MnO2 decreases and the specific surface area increases, which provides more active sites for the electrode material. When 3 mmol Al3+ is added, the prepared MnO2-3 has the largest specific capacitance and the highest rate performance. The energy density of the asymmetric supercapacitor (ASC) with MnO2-3 as the positive electrode and activated carbon (AC) as the negative electrode can reach 18.4 W·h/kg at the power density of 400 W/kg, and the capacity can maintain 90% of the initial value after 20000 cycles, indicating that Al-doped MnO2 has certain practical application value. This study provides favorable guidance for MnO2 as a high performance electrode material.