Colloidal Processing of Mn3O4-Carbon Nanotube Nanocomposite Electrodes for Supercapacitors.

Wenjuan Yang,Igor Zhitomirsky

doi:10.3390/nano12050803

Abstract

This investigation addresses the challenges in the development of efficient nanostructured Mn3O4 cathodes for supercapacitors. A high areal capacitance and the ability to avoid a time-consuming activation procedure for electrodes with high active mass loading of 40 mg cm−2 are reported. This facilitates practical applications of Mn3O4 based electrodes. The highest capacitance of 6.11 F cm−2 (153 F g−1) is obtained from cyclic voltammetry at a scan rate of 2 mV s−1 and 6.07 F cm−2 (151.9 F g−1) from the chronopotentiometry at a current density of 3 mA cm−2 in a potential window of 0.9 V in a neutral Na2SO4 electrolyte. The new approach is based on the application of rhamnolipids (RL) as a capping agent for the synthesis of Mn3O4 particles and a co-dispersant for Mn3O4 and carbon nanotubes, which are used as conductive additives. The size and shape of the Mn3O4 particles are influenced by RL. The enhanced performance of the electrodes is linked to the chemical structure and properties of RL molecules, which exert influence on Mn3O4 particle size and shape during synthesis, reduce agglomeration, facilitate RL adsorption on Mn3O4 and carbon nanotubes, and influence their co-dispersion and mixing at the nanometric scale.

Highlights

Colloidal methods are widely used for the fabrication of advanced nanomaterials and nanocomposites [1–3]
Significant interest has been generated in co-dispersants for efficient mixing of the charge storage materials with conductive additives [8]
The results presented below indicated that the shape and size of the synthesized Mn3 O4 particles is influenced by RL

Summary

Introduction

Colloidal methods are widely used for the fabrication of advanced nanomaterials and nanocomposites [1–3]. The use of surfactants for colloidal nanofabrication allows efficient control of particle size and prevention of their agglomeration [4–7]. It was found that surfactants facilitate the fabrication of nanoparticles of inorganic charge storage materials with small particle size and prevent their agglomeration [8]. Significant interest has been generated in co-dispersants for efficient mixing of the charge storage materials with conductive additives [8]. The use of such co-dispersants for colloidal fabrication allowed for significant improvement of electrochemical performance of supercapacitors and batteries for practical applications [8,9]. Advanced techniques were developed for the fabrication of activated carbon, graphene, carbon fiber, MXene, metal oxide and hydroxide electrodes with high porosity [15–19]

Methods

Results

Conclusion