Redox stoichiometric ratio mediated fast (4 h) hydrothermal synthesis of Na0.44MnO2 nanowires for high pseudocapacitive Na+ ion supercapacitors

• Published in: Materials letters 2023-04, Vol.337, p.133931, Article 133931
• Main Authors: Li, Shiyao, Wang, Zixuan, Liu, Cai
• Format: Article
• Language: English
• Subjects: Energy storage and conversion; Na0.44MnO2; Nanowire; Pseudocapacitor; Redox hydrothermal reaction
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/j.matlet.2023.133931

[Display omitted] •Na0.44MnO2 nanowires were prepared by one-pot hydrothermal reaction.•Hydrothermal reaction time was shorted into 4 h.•The fast synthesis is due to the stoichiometric ratio of raw materials.•Na0.44MnO2 nanowire had a pseudocapacitive Na+ ion storage mechanism. Key issue for Na-ion supercapacitors is facile preparation of electrode active materials with high electrochemical performance. In this paper, 4 h preparation of Na0.44MnO2 nanowires (2.34 g/50 mL) were achieved by the redox hydrothermal reactions of KMnO4 and MnSO4. The fast synthesis is due to the stoichiometric ratio of raw materials (MKMnO4/MMnSO4 = 14/31): (1) fast generation of Na-birnessite from the redox reaction of KMnO4 and MnSO4, and (2) fast generation of Na0.44MnO2 from redox hydrothermal reaction of Na-birnessite and Mn2+. Na0.44MnO2 nanowire electrodes had a pseudocapacitive Na+ ion storage mechanism, a high specific capacity (263.6F/g at 0.1 A/g) and a good capacity retention (almost 100 %) after 5000 cycles at 10 A/g.