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Chodankar, Nilesh R,Dubal, Deepak P,Kwon, Yongchai,Kim, Do-Heyoung Nature Publishing Group 2017 NPG Asia Materials Vol.9 No.8
<P>Currently, one-dimensional nanostructured binary metal oxides attract a great attention in supercapacitors (SCs) application due to their rapid charge transportation. In this respect, different nanostructures of FeCo2O4 are designed by simply tuning the reaction temperature in hydrothermal synthesis. These nanostructures are directly grown on flexible stainless steel mesh and further applied as binder-free electrodes for SCs. The systematic study is carried out to confirm the relation between surface characteristics and electrochemical properties of FeCo2O4 thin film. Among different nanostructures, FeCo2O4 nanowire arrays exhibit hierarchical mesoporous structure and demonstrate good surface properties including high surface area and appropriate pore volume. As a consequence, relatively high specific capacitance of 1963 F g(-1) is obtained for the FeCo2O4 nanowire electrode. Further, asymmetric SC is fabricated using nanowired-FeCo2O4 and nanoparticulated-MnO2 thin films as negative and positive electrodes with neutral Na2SO4 electrolyte. Impressively, the MnO2//FeCo2O4 cell could be successfully cycled in a wide voltage window of 2.0 V, which can achieve a specific capacitance of 218 F g(-1) and energy density of 43 Wh kg(-1). In addition, the SCs exhibit improved capacitance with cycling, which is attributed to opening of micro-pores occurred by frequent ion transport.</P>
Chodankar, Nilesh R.,Ji, Su-Hyeon,Kim, Do-Heyoung Elsevier 2017 JOURNAL- TAIWAN INSTITUTE OF CHEMICAL ENGINEERS Vol.80 No.-
<P><B>Abstract</B></P> <P>Herein we developed a nanocomposite of MnO<SUB>2</SUB> and multiwall carbon nanotubes (MWCNTs) deposited on a stainless-steel mesh substrate using a simple and scalable chemical approach to greatly expand the capacitive performance of MnO<SUB>2</SUB>-based electrodes. Electrochemical investigations of the chemically prepared MWCNTs/MnO<SUB>2</SUB> nanocomposite showed that it has high specific capacitance (614 F/g), high specific energy (85.3 Wh/kg), and high stability over 2500 cycles. The enhanced capacitive performance of the MWCNTs/MnO<SUB>2</SUB> nanocomposite was analyzed by calculating the surface-controlled and diffusion-controlled charge components. A symmetric solid-state supercapacitor using a MWCNTs/MnO<SUB>2</SUB> nanocomposite electrode and polyvinyl alcohol (PVA)-Na<SUB>2</SUB>SO<SUB>4</SUB> gel electrolyte achieved a cell voltage of 1.0 V and a maximum specific capacitance of 204 F/g with an energy density of 28.33 Wh/kg. Furthermore, the assembled symmetric solid-state supercapacitor achieved coulombic efficiency of 99.04%. The excellent electrochemical features of the MWCNTs/MnO<SUB>2</SUB> nanocomposite electrode make it a promising material for application in future capacitor-based energy storage systems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> MWCNTs/MnO<SUB>2</SUB> nanocomposite on stainless steel mesh electrode was prepared by electrodeposition. </LI> <LI> The integrated MWCNTs/MnO<SUB>2</SUB> nanocomposite electrode delivers extraordinary electrochemical characteristics. </LI> <LI> Symmetric solid-state supercapacitor based on MWCNTs/MnO<SUB>2</SUB> nanocomposite electrode was successfully assembled. </LI> <LI> The assembled symmetric solid-state supercapacitor exhibits high energy density of 28.33 Wh/kg. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Fig. (a) shows the representative SEM image of MWCNT/MnO<SUB>2</SUB> nanocomposites with (b) the Ragone plot of the symmetric flexible solid-state supercapacitor designed in this study, in comparison with others reported in the literature.</P> <P>[DISPLAY OMISSION]</P>
박범준,( Nilesh R. Chodankar ),허윤석,한영규 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
In present work, P doped RC-OH (P@RC-OH) nanofibers has been directly prepared over three dimensional (3D) highly conducting nickel (Ni) foam substrate by the single-step room temperature potentiodynamic polarization method for high energy and stable solid-state hybrid SCs. As a result, the prepared P@RC-OH electrode shows the excellent specific capacity of 262.3 mA h/g at scan rate of 100 mV/s which is quite higher than the other samples. Moreover, the P@RC-OH electrode shows the excellent cycling stability over 20000 cycles by maintain the 90 % of initial capacity. The assembled quasi-solid-state hybrid SCs with P@RC-OH as a positive and activated carbon (AC) as a negative electrode delivers ultrahigh specific capacity of 440 mA h/g at current density of 4 mA/cm2. Additionally, the assembled hybrid SCs exhibits the energy density of 90.02 Wh/kg at a power density of 1363 W/kg and remarkable cycling stability over 10000 charge-discharge cycles.
Towards flexible solid-state supercapacitors for smart and wearable electronics
Dubal, Deepak P.,Chodankar, Nilesh R.,Kim, Do-Heyoung,Gomez-Romero, Pedro The Royal Society of Chemistry 2018 Chemical Society reviews Vol.47 No.6
<P>Flexible solid-state supercapacitors (FSSCs) are frontrunners in energy storage device technology and have attracted extensive attention owing to recent significant breakthroughs in modern wearable electronics. In this study, we review the state-of-the-art advancements in FSSCs to provide new insights on mechanisms, emerging electrode materials, flexible gel electrolytes and novel cell designs. The review begins with a brief introduction on the fundamental understanding of charge storage mechanisms based on the structural properties of electrode materials. The next sections briefly summarise the latest progress in flexible electrodes (<I>i.e.</I>, freestanding and substrate-supported, including textile, paper, metal foil/wire and polymer-based substrates) and flexible gel electrolytes (<I>i.e.</I>, aqueous, organic, ionic liquids and redox-active gels). Subsequently, a comprehensive summary of FSSC cell designs introduces some emerging electrode materials, including MXenes, metal nitrides, metal-organic frameworks (MOFs), polyoxometalates (POMs) and black phosphorus. Some potential practical applications, such as the development of piezoelectric, photo-, shape-memory, self-healing, electrochromic and integrated sensor-supercapacitors are also discussed. The final section highlights current challenges and future perspectives on research in this thriving field.</P>
Aqueous asymmetric supercapacitor based on RuO<sub>2</sub>-WO<sub>3</sub> electrodes
Ji, Su-Hyeon,Chodankar, Nilesh R.,Kim, Do-Heyoung Elsevier 2019 ELECTROCHIMICA ACTA Vol.325 No.-
<P><B>Abstract</B></P> <P>Designing high-energy asymmetric supercapacitors(SC) with appropriate positive and negative electrodes is urgently required to expand their practical applicability. The redox-active materials are beneficial for high-energy SC applications because of their multiple oxidation states and higher energy storage capacity than the traditional carbon-based materials. In this work, for the first time, we have designed and developed high-energy aqueous asymmetric SC by combining hexagonal WO<SUB>3</SUB> and hydrous RuO<SUB>2</SUB> in a single cell. Initially, the hexagonal (h) WO<SUB>3</SUB> and hydrous RuO<SUB>2</SUB> is directly prepared on three-dimensional conducting carbon cloth. Because of their higher electrical conductivity, nanoporous surface morphology, and redox activity, the prepared hydrous RuO<SUB>2</SUB> and WO<SUB>3</SUB> exhibit excellent electrochemical features in the positive and negative potential window, respectively, with aqueous H<SUB>2</SUB>SO<SUB>4</SUB> electrolyte. The assembled RuO<SUB>2</SUB>//h-WO<SUB>3</SUB> asymmetric SC device exhibits outstanding electrochemical performance in an operating voltage window of 1.6 V, excellent cycling stability of ∼171.75% (after 6500 cycles), and energy density of 1.25 Wh/cm<SUP>3</SUP> (16.92 W h/kg) at a power density of 40 W/cm<SUP>3</SUP> (540 W/kg). These results show that redox-active materials can prominently enhance the energy storage capacity of SC than the traditional carbon-based asymmetric SCs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Aqueous asymmetric SCs has been developed with hydrous RuO<SUB>2</SUB> and h-WO<SUB>3</SUB> as a positive and negative electrode. </LI> <LI> Binder-less approach has been developed to prepare hydrous RuO<SUB>2</SUB> and h-WO<SUB>3</SUB> over the flexible CC. </LI> <LI> RuO<SUB>2</SUB>//h-WO<SUB>3</SUB> aqueous asymmetric supercapacitor cell showed high energy density of 1.25 Wh/cm<SUP>3</SUP>. </LI> <LI> The device exhibited excellent long-term cycling stability (∼171.75% after 6500 cycles). </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>In this paper, hydrous RuO<SUB>2</SUB> and h-WO<SUB>3</SUB> were directly grown on the carbon cloth for fabricating the aqueous asymmetric supercapacitor. The developed asymmetric supercapacitor shows excellent energy storing capacity with better rate capability and cycling stability.</P> <P>[DISPLAY OMISSION]</P>
( Seyed Majid Ghoreishian ),( Nilesh R. Chodankar ),허윤석 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
In the present work, rationally prepared carbon fiber (CF)-supported high-mass-loaded 2D-nanosheet-based MnO<sub>2</sub> (MnO<sub>2</sub>@CF, 6.6 mg/㎠) and MoS<sub>2</sub> (MoS<sub>2</sub>@CF, 7.2 mg/㎠) were used in a high-energy pseudocapacitor. These hierarchical 2D nanosheets yielded outstanding areal capacitances of 1187 and 495 mF/㎠ at high current densities with excellent cycling stability. Pliable all-pseudocapacitive solid-state asymmetric supercapacitor was designed using MnO<sub>2</sub>@CF and MoS<sub>2</sub>@CF as the positive and negative electrodes, respectively, with ultrahigh mass loading of 14.2 mg/㎠. The assembled solid-state asymmetric cell conveyed an energy density of 1.87 mWh/㎤ at a power density of 70 mW/㎤, and it showed capacitance retention of 92.25% over 11000 cycles and a very small diffusion resistance (1.72 Ω/s1/2). Thus, it is superior to most state-of-the-art reported pseudocapacitors.