Electrocatalytic activity of MnO2 nanosheet array-decorated carbon paper as superior negative electrode for vanadium redox flow batteries. (1st November 2019)

• Record Type: Journal Article
• Authors: Jiang, Yingqiao; Feng, Xiaojian; Cheng, Gang; Li, Yuehua; Li, Chuanchang; He, Zhangxing; Zhu, Jing; Meng, Wei; Zhou, Huizhu; Dai, Lei; Wang, Ling
• Is Part Of: Electrochimica acta. Volume 322(2019)
• Publication Date: 2019-11-01
• Subjects: Energy storage -- Vanadium redox flow batteries -- Carbon paper -- MnO2 nanosheets -- Electrochemical kinetics; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2019.134754
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: An in-situ and controllable redox deposition method has been applied to prepare binder-free MnO2 nanosheet array-decorated carbon paper as negative electrode for vanadium redox flow batteries (VRFB). Electrochemical performance of electrode depends on amount and uniform distribution of MnO2 on carbon paper, which were controlled by solution pH, KMnO4 concentration, and deposition time. Modified carbon paper (CPA-05-30) with a uniform MnO2 nanosheet coating layer was obtained in 0.05 M KMnO4 + 0.5 M H2 SO4 solution for 30 min. CPA-05-30 presents the most excellent electrocatalytic performance for V 3+ /V 2+ redox reaction. On CPA-05-30, charge transfer and diffusion processes for V 3+ /V 2+ redox reaction are accelerated as a result of MnO2 nanosheet with high catalytic activity and excellent hydrophilcity. Therefore, loading MnO2 on carbon paper improves electrochemical activity V 3+ /V 2+ redox reaction. Moreover, in charge-discharge test, the cell using CPA-05-30 as negative electrode shows higher discharge capacity and better capacity retention at 50 mA cm −2 for 50 cycles in comparison with pristine cell. It indicates that MnO2 nanosheet can efficiently increase electrolyte utilization. At 100 mA cm −2, energy efficiency of the cell using CPA-05-30 is 66.4%, which is 6.0% higher than that of pristine cell. MnO2 nanosheet decorated carbon paper shows excellent electrochemical properties for energy storage application, which evidences its potential application in VRFB. Graphical abstract: Image 1