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Associate Professor Dr. Montree Sawangphruk

Chemical Engineering
School of Energy Science and Engineering (ESE)
Tel. +66(0) 33 014251
Email montree.s@vistec.ac.th
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Carbon and metal oxide nanofibers for energy storage technology

 

Research Overview

Supercapacitors are very attractive energy storage devices because they have higher power density than batteries and higher energy density than conventional capacitors. They are used in many applications such as hybrid electric vehicles, public transportation buses, and portable electronic devices. Supercapacitors can be classified by their charge storage mechanisms including electrochemical double layer capacitors (EDLCs) and pseudocapacitors. EDLCs are based on a physical adsorption at an interface of solid electrode and liquid electrolyte. Carbon fiber is typically used as active materials in EDLCs due to their high surface area and porosity as well as structural stability. In addition, transition metal oxide is widely used as active material in psuedocapacitors type, e.g. NiO, Co3O4, MnO2, and Mn3O4. Espectially, porous structure of metal oxide nanofibers by electrospinning process showed the high electrochemical performance because one-dimensional and porous nanofibers enhances specific surface area, which increases contact area between electrolyte ions and surface of the electrodes. Moreover, electrospinning process is the simple technique for synthesis of metal oxide nanofibers. Our research team investigate the modification and preparation of carbon fibers and related material nanofibers in supercapacitor application.

Carbon fibers

Carbon fiber paper (CFP), carbon cloth, which are conductive materials are so important contributing the heavy weight to the whole device. More importantly, the stability of the metal current collectors are rather poor when used in aqueous-based supercapa citors since the corrosion of metal with anions of the electrolytes (e.g., NO3-, Cl-, SO42-) spontaneously occurs limiting the practical use of the aqueous-based supercapacitors. In fact, the diffusion of the electrolyte in water is much faster than that in organic solvents leading to higher specific power. CFP has many advantages suitably to be used as the conductive substrate or current collector including high flexibility, corrosive resistance, porosity, and conductivity.

In this work, the chemical surface functionalization of CFP (f-CFP) was finely tuned using a mixed acid treatment with keeping high bulk conductivity of the CFP. Interestingly, it is found that oxygen containing groups on the CFP surface can introduce the pseudocapacitance due to a surface redox reaction at a solid-liquid interface [1].

There are a number of advantages of using f-CFP as the conductive substrates. In this work, we electrodeposited PANI on hydrophilic functionalized carbon fiber paper (f-CFP) and used as the pseudocapacitors. The carboxyl and hydroxyl groups of the f-CFP can chemically interact via H-bonding with PANI leading to high stability of the subsequently as-fabricated pseudocapacitors. The as-fabricated pseudocapacitor devices of PANI/f-CFP electrodes in both aqueous and organic electrolytes exhibit high charge storage performances due to their high porosity, high electronic and ionic conductivities, and high stability [2].
    
 
Carbon and metal oxide fibers can be procuced by electrospining process of polymer fiber and then heat treatment. Electrospinning process is the preparation method of polymer fiber with diameter range from microfiber to nanofiber. Electrospinning equipment consists of a syringe, syringe pump, spinneret, current collector, and high voltage power supply.

Metal Oxide nanofibers

Manganeses oxide-based materials are one of the great interesting materials for energy storage application because of their relatively low cost, low toxicity and environmental compatibility [3].
 

Recently, spinel type oxides from transition metals (such as AB2O4 type), particularly the cobalt-manganese oxide (MnCo2O4) with Fd3m space group had intensive attraction as an electrode material for electro-catalyst and advance energy storage devices due to its low cost, low toxicity, easy synthesis, and the key purpose is its good stability, and high electro-catalytic activity. While cobalt- based metal has high redox activity and reversibility. Manganese can provide good transporting electron providing higher capacitive capacitance. Additionally, the structure with mixed valance band gives better electronic conductivity, which can improve electron transfer between electrode and electrolyte, and high redox-reaction form solid-state redox exchanging between couple cations (Mn and Co), so the MnCo2O4 are appropriate to use as active materials for the supercapacitor. In addition, the theoretical capacitance of MnCo2O4 (3,620 F/g) is higher than its parent compound (3,590 F/g). The morphology of active materials extremely have an impact to the performance of a supercapacitor device, especially 1D nano-structure were prepared by electrospinning technique which can enhance the ions transfer rate and reduce diffusion path for charge. So, the MnCo2O4 are suitable candidate to use as active material for the supercapacitor.

      

FE-SEM images of (a) as-prepared fibers,(b) MnCo2O4 Nanotubular-fibers, and (c,d) TEM image of MnCo2O4 Nanotubular-fibers [(c) low magnification, (d) High magnification]
 

Selected Publications

  • P. Suktha, P. Chiochan, P. Iamprasertkun, J. Wutthiprom, N. Phattharasupakun, M. Suksomboon, et al., Electrochimica Acta, vol. 176, pp. 504-513, 9/10/ 2015.
  • T. Kaewsongpol, M. Sawangphruk, P. Chiochan, M. Suksomboon, P. Suktha, P. Srimuk, et al., Materials Today Communications, vol. 4, pp. 176-185, 9// 2015.
 

Research Group Members:

Dr. Montree Sawangphruk (Assistant Professor)
Dr. Saran Kalasina (Postdoctoral Research Fellow)
Ms. Atiweena Krittayavathananon
Mr. Poramane Chiochan
Mr. Chan Tanggarnjanavalukul
Ms. Montakan Suksomboon
Mr. Nutthaphon Phattharasupakun
Ms. Juthaporn Wutthiprom
Ms. Siriroong Kaewruang
Mr. Jakkrit Khuntilo
Ms. Phansiri Suktha
Mr. Pawin Iamprasertkun
Mr. Tanut Pettong
Ms. Pichamon Sirisinudomkit
 

International Research Collaborator:

Prof. John S Foord
University of Oxford