Preparation of Spherical δ-MnO 2 Nanoflowers by One-Step Coprecipitation Method as Electrode Material for Supercapacitor

• Published in: ACS omega 2024-04, Vol.9 (16), p.18032-18045
• Main Authors: Zhang, Dazhi, Dai, Jiamian, Zhang, Jiajia, Zhang, Yixin, Liu, Honglai, Xu, Yunhui, Wu, Jianjun, Li, Peipei
• Format: Article
• Language: English
• ISSN: 2470-1343; 2470-1343
• DOI: 10.1021/acsomega.3c09725

Spherical δ-MnO nanoflower materials were synthesized via a facile one-step coprecipitation method through adjusting the molar ratio of KMnO to MnSO . The influence of the molar ratio of the reactants on the crystal structure, morphology, and electrochemical performances was investigated. At a molar ratio of 3.3 for KMnO to MnSO , the spherical δ-MnO nanoflowers composed of nanosheets with the highest specific surface area (228.0 m g ) were obtained as electrode materials. In the conventional three-electrode system using 1 M Na SO as an electrolyte, the specific capacitance of the spherical δ-MnO nanoflowers reached 172.3 F g at a current density of 1 A g . Moreover, even after 5000 cycles at a current density of 5 A g , the GCD curves remained essentially unchanged, and the specific capacitance still retained 86.50% of the maximum value. The kinetics of the electrode reaction were preliminarily studied through the linear potential sweep technique to observe diffusion-controlled contribution toward total capacitance. For the spherical δ-MnO nanoflower electrode material, diffusion-controlled contribution accounted for 65.1% at low scan rates and still remained significant at high scan rates (100 mV s ), indicating excellent utilization efficiency of the bulk phase. The as-fabricated asymmetric supercapacitor HFC-7//MnO -3.3-ASC presented a prominent specific energy of 16.5 Wh kg at the specific power of 450 W kg . Even when the specific power reached 9.0 kW kg , the energy density still retained 9.5 Wh kg .