Controllable electrochemical activation of Mn3O4: Anion effect on phase transition, morphology and capacitive performance

作者：Liu, Cuiyin^*; Chen, Yanfeng; Huang, Hong; Duan, Chongxiong; Ma, Xinzhou; Wang, Guangjin; Luo, Jie; Luo, Haochuan; Li, Jingling^*

来源：Electrochimica Acta, 2022, 416: 140281.

DOI：10.1016/j.electacta.2022.140281

• Mn3O4
• Birnessite
• Electrochemical activation
• Electrolyte
• Capacitive performance

It has not been considered in the reported literatures that the anion additive in aqueous electrolyte controls the electrochemical activation of Mn3O4. Here, with the addition of different anions, we clarify their effects on the activation efficiency and its relationship with the capacitive performance. Less efficient activation is present with MoO(4)(2- )or WO(4)(2-)additive in comparisons to the F- and CO(3)(2-)species. By controlling MoO(4)(2-)concentration, the efficiency of phase transition, lateral dimension of nanosheets and Mn oxidation state can be modulated. Based on the detection of positive potential shift on the oxidation peak of Mn3O4, it is proposed that the additional anions affect the phase transition mechanism of Mn3O4 through the formation of Mn(II) precipitates. The first-principles calculations demonstrate that the Mn(II) precipitates have different oxidative activities, which may cause oxidation limitation of Mn3O4 so as to regulate the activation efficiency. With suitable concentration of MoO42-, enhanced cycling stability with a specific capacitance of 401.3 F g(-1) at 1 A g(-1) is achieved. This work may be useful for further development of practical manganese oxide electrodes.

• 单位
  佛山科学技术学院; 东莞理工学院