Controllable electrochemical activation of Mn3O4: Anion effect on phase transition, morphology and capacitive performance. (1st June 2022)

• Record Type: Journal Article
• Authors: Liu, Cuiyin; Chen, Yanfeng; Huang, Hong; Duan, Chongxiong; Ma, Xinzhou; Wang, Guangjin; Luo, Jie; Luo, Haochuan; Li, Jingling
• Is Part Of: Electrochimica acta. Volume 416(2022)
• Publication Date: 2022-06-01
• Subjects: Mn3O4 -- Birnessite -- Electrochemical activation -- Electrolyte -- Capacitive performance; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2022.140281
• Languages: English
• ISSNs: 0013-4686

Abstract

Highlights: Controllable electrochemical activation of Mn3 O4 is present with anion additive in aqueous electrolyte. The lateral dimension of birnessite nanosheets is in-situ tuned by MoO4 2− concentration. The anion effect mechanism on the spinel-to-layer phase transition is clarified. Enhanced cycling stability with a high specific capacitance is achieved. Abstract: It has not been considered in the reported literatures that the anion additive in aqueous electrolyte controls the electrochemical activation of Mn3 O4 . 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 MoO4 2− or WO4 2− additive in comparisons to the F − and CO3 2− species. By controlling MoO4 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 Mn3 O4, it is proposed that the additional anions affect the phase transition mechanism of Mn3 O4 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 Mn3 O4 so as to regulate the activation efficiency. With suitable concentration of MoO4 2−, 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. Graphical abstract: The anion effect on the electrochemical activation of Mn3 O4 has been elucidated. The activation efficiency is modulated with added MoO4 2− through their bonding with dissolved Mn 2+ . By tuning the MoO4 2− concentration, controlled lateral dimension of nanosheets and enhanced cycling stability with an anticipated specific capacitance are achieved. Image, graphical abstract