In-Situ Electrochemical Preparation of Mnox/Cc with Porous Structure and Mixed Valence for Supercapacitor

Abstract

Manganese oxide (MnOx) with an ultra-high theoretical specific capacitance is a prospective material for supercapacitors. However, the poor conductivity degrades the capacitive performance of MnOx.Herein, MnOx/carbon cloth (MnOx/CC) with a porous structure and mixed valence was in-situ prepared by an electrodeposition-electrooxidation method.The looseand porous lamellar structure of MnOxCC-R(V6T4800)-O(V2T1600) increased the contact area between the electrode and the electrolyte, provided abundant active sites and mitigated the volume expansion during the ion insertion/extraction process. Meanwhile，The optimal ratio of Mn(Ⅲ） to Mn(Ⅳ) in MnOx/CC-R(V6T4800)-O(V2T1600) significantly improved the conductivity of MnOx. Therefore, the electrochemical performance of MnOx was effectively enhanced with a favorable specific capacitance up to 2591.2 mF∙cm-2 (205.1 F∙g-1) at 1 mA⸱cm-2, an outstanding rate capacity (81.2% retention at 1 to 20 mA⸱cm-2) and superior cycle performance (91.2% after 5000 cycles). Moreover, the asymmetric supercapacitor MnOx/CC//Fe2O3/CC could reach 768.2 mF⸱cm-2 at 1 mA⸱cm-2 and had 78.4% retention after 10000 cycles. In this work, we demonstrated the effectiveness of this in-situ electrochemical preparation of porous structure and mixed valence materials, which we hope will help develop high-performance electrode materials.

Keywords: Manganese oxide, Porous structure, Mixed valence, Electrodeposition-electrooxidation, Supercapacitors