Facile Low-temperature Chemical Synthesis and Characterization of a Manganese Oxide/multi-walled Carbon Nanotube Composite for Supercapacitor Applications

• Published in: Bulletin of the Korean Chemical Society Vol. 35; no. 10; pp. 2974 - 2978
• Main Authors: Jang, Kihun, Lee, Sung-Won, Yu, Seongil, Salunkhe, Rahul R, Chung, Ildoo, Choi, Sungmin, Ahn, Heejoon
• Format: Journal Article
• Language: Korean
• Published: 2014
• Subjects: Manganese oxides; Composite materials; Carbon nanotubes; Supercapacitor; Chemical synthesis
• ISSN: 0253-2964; 1229-5949

$Mn_3O_4$/multi-walled carbon nanotube (MWCNT) composites are prepared by chemically synthesizing $Mn_3O_4$ nanoparticles on a MWCNT film at room temperature. Structural and morphological characterization has been carried out using X-ray diffraction (XRD) and scanning and transmission electron microscopies (SEM and TEM). These reveal that polycrystalline $Mn_3O_4$ nanoparticles, with sizes of about 10-20 nm, aggregate to form larger nanoparticles (50-200 nm), and the $Mn_3O_4$ nanoparticles are attached inhomogeneously on MWCNTs. The electrochemical behavior of the composites is analyzed by cyclic voltammetry experiment. The $Mn_3O_4$/MWCNT composite exhibits a specific capacitance of $257Fg^{-1}$ at a scan rate of $5mVs^{-1}$, which is about 3.5 times higher than that of the pure $Mn_3O_4$. Cycle-life tests show that the specific capacitance of the $Mn_3O_4$/MWCNT composite is stable up to 1000 cycles with about 85% capacitance retention, which is better than the pure $Mn_3O_4$ electrode. The improved supercapacitive performance of the $Mn_3O_4$/MWCNT composite electrode can be attributed to the synergistic effects of the $Mn_3O_4$ nanoparticles and the MWCNTs, which arises not only from the combination of pseudocapacitance from $Mn_3O_4$ nanoparticles and electric double layer capacitance from the MWCNTs but also from the increased surface area, pore volume and conducting property of the MWCNT network.