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>

Sponge-like β-Ni(OH)2 nanoparticles: synthesis, characterization and electrochemical properties

Dubal, D. P.,Lee, S. H.,Kim, W. B. Springer-Verlag 2012 JOURNAL OF MATERIALS SCIENCE - Vol.47 No.8

Demonstrating the Highest Supercapacitive Performance of Branched MnO₂Nanorods Grown Directly on Flexible Substrates using Controlled Chemistry at Ambient Temperature

Dubal, Deepak P.,Kim, Jong Guk,Kim, Youngmin,Holze, Rudolf,Kim, Won Bae Wiley Blackwell (John Wiley Sons) 2013 Energy technology Vol.1 No.2

Surfactant-assisted morphological tuning of hierarchical CuO thin films for electrochemical supercapacitors

Dubal, Deepak P.,Gund, Girish S.,Holze, Rudolf,Jadhav, Harsharaj S.,Lokhande, Chandrakant D.,Park, Chan-Jin The Royal Society of Chemistry 2013 Dalton Transactions Vol.42 No.18

<P>Copper oxide (CuO) thin films are successfully synthesized using a surfactant assisted chemical bath deposition method for application in supercapacitors. The effect of organic surfactants such as Triton X-100 and polyvinyl alcohol (PVA) on structural, morphological, surface areas and electrochemical properties of CuO thin films is investigated. The films deposited using organic surfactants exhibit different surface morphologies. It is observed that the organic surfactants play important roles in modifying the morphology, surface area and pore size distribution. Electrochemical analysis confirms that the nanostructures of the electrode material play a vital role in supercapacitors. The cyclic voltammetry studies show a considerably improved high rate pseudocapacitance of CuO samples synthesized using organic surfactants. The maximum specific capacitance of 411 F g<SUP>−1</SUP> at 5 mV s<SUP>−1</SUP> is obtained for the CuO sample prepared using an organic surfactant (Triton X-100). Furthermore, all the CuO nanostructures exhibit high power performance, excellent rate as well as long term cycling stability. The Ragone plot ascertains better power and energy densities of CuO nanostructured samples. This is an easy and simple way to tune the morphology using surfactants which can be applied for other energy storage materials.</P> <P>Graphic Abstract</P><P>Copper oxide (CuO) thin films are successfully synthesized using a surfactant assisted chemical bath deposition method for application in supercapacitors. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3dt50275a'> </P>

Porous polypyrrole clusters prepared by electropolymerization for a high performance supercapacitor

Dubal, Deepak P.,Lee, Sang Ho,Kim, Jong Guk,Kim, Won Bae,Lokhande, Chandrakant D. The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.7

<P>Different nanostructures (Ns), such as nanobelts, nanobricks and nanosheets, of polypyrrole (PPy) were successfully fabricated on stainless steel substrates by simply varying the scan rate of deposition in the potentiodynamic mode. These PPy Ns were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and surface area measurement. The XRD analysis showed the formation of amorphous PPy thin films, and the FTIR studies confirmed characteristic chemical bonding in the PPy materials. SEM images depicted that a high scan rate of deposition can form multilayer nanosheets with high porosity leading to a system with excellent processability. The PPy nanosheets possess a higher Brunauer–Emmett–Teller (BET) surface area of 37.1 m<SUP>2</SUP> g<SUP>−1</SUP> than PPy nanobelts and nanobricks. The supercapacitive performances of different PPy Ns were evaluated using cyclic voltammetry (CV) and galvanostatic charge–discharge techniques in 0.5 M H<SUB>2</SUB>SO<SUB>4</SUB>. A maximum specific capacitance of 586 F g<SUP>−1</SUP> was obtained for multilayer nanosheets at a scan rate of 2 mV s<SUP>−1</SUP>. In addition, impedance measurements of the different Ns of PPy electrodes were performed suggesting that the PPy electrodes with multilayer nanosheets are promising materials for the next generation high performance electrochemical supercapacitors.</P> <P>Graphic Abstract</P><P>Simple and inexpensive electropolymerization enables the synthesis of three dimensional PPy nanostructures with large area and flexibility for applications in supercapacitors. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm14470k'> </P>

Gastric per-oral endoscopic myotomy: Indications, technique, outcomes, and future directions

Amol Bapaye,Nachiket A. Dubale 소화기인터벤션의학회 2020 Gastrointestinal Intervention Vol.9 No.2

After the clinical success of per-oral endoscopic myotomy (POEM) for treatment of achalasia cardia, the principle of submucosal tunneling and mucosal flap valve has been used in several other areas of the gastrointestinal tract. Gastric per-oral endoscopic pyloromyotomy (G-POEM, POEP, POP) is a relatively new procedure described for the treatment of refractory gastroparesis. This review discusses the indications, patient selection, pre-procedure workup, and procedure details of G-POEM. It also reviews the current literature on this procedure and provides insights and future directions for research on this topic.

Direct growth of FeCo2O4 nanowire arrays on flexible stainless steel mesh for high-performance asymmetric supercapacitor

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>

Baking impact of Fe composition on CdSe films for solar cell application

Shinde, S.K.,Dubal, D.P.,Ghodake, G.S.,Lee, D.S.,Lohar, G.M.,Rath, M.C.,Fulari, V.J. North-Holland 2014 Materials letters Vol.132 No.-

Cd<SUB>1-X</SUB>Fe<SUB>X</SUB>Se thin films were electrodeposited onto fluorine doped tin oxide coated conducting glass (FTO) and stainless steel (SS) substrates at various bath compositions with X=0.1 to 0.5 in an aqueous electrolytic bath containing CdSO<SUB>4</SUB>, FeSO<SUB>4</SUB> and SeO<SUB>2</SUB>. The effects of different compositions on physico-chemical properties of Cd1-XFeXSe thin films have been systematically investigated. The X-ray diffraction (XRD) analysis reveals the polycrystalline in nature of Cd<SUB>1-X</SUB>Fe<SUB>X</SUB>S thin films. Field emission scanning electron microscopy (FE-SEM) micrographs shows the variation in the nanostructure with varying compositions. The Cd<SUB>1-X</SUB>Fe<SUB>X</SUB>Se thin films exhibited the water contact angles in hydrophilic range. Optical absorption measurements are used to estimate the band gap value of Cd<SUB>1-X</SUB>Fe<SUB>X</SUB>Se thin films deposited at various bath compositions. The dramatic changes in surface morphology, as a consequence of different composition of Fe in CdSe matrix, significantly alter the conversion efficiency of Cd<SUB>1-X</SUB>Fe<SUB>X</SUB>Se films.

Enhanced photoelectrochemical properties of nanoflower-like hexagonal CdSe0.6Te0.4: Effect of electron beam irradiation

수렌드라,가야난고다크,Deepak P. Dubal,Haridas D. Dhaygude,김대영,Vijay J. Fulari 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.45 No.-

Present investigation deals with the effect of electron beam irradiation on the photoelectrochemicalproperties of cadmium selenium telluride (CdSe0.6Te0.4) thin films. Initially, CdSe0.6Te0.4 thin films wereelectrodeposited on fluorine doped tin oxide (FTO) coated glass and stainless steel substrates. Later,these CdSe0.6Te0.4 thin films were irradiated with high energy electron beam(10 MeV) of different dosesfrom 10 to 30 kilograys (kGy). The effect of electron beam irradiation on different physico-chemicalproperties of CdSe0.6Te0.4 thin films such asmorphological, structural, optical and photoelectrochemicalhas been investigated. It is observed that, the electron beam irradiation treatment considerably affectsthe properties of CdSe0.6Te0.4 thin films. The surface morphology of CdSe0.6Te0.4 thin films was changedfrom cauliflowers to nanoflowers, nanoroses and interconnected nanoflakes with doses of electronbeams. Furthermore, the effect of electron beam irradiation on photoelectrochemical properties ofCdSe0.6Te0.4 films was investigated. It is interesting to note that, the photoelectrochemical (PEC)properties of CdSe0.6Te0.4 thin films are extensively affected by electron beam irradiation. Thephotoconversion efficiency values of CdSe0.6Te0.4 films for different doses of electron beam are found tobe 0.9%, 1.1%, 2.0% and 1.5%, respectively.

Gastric per-oral endoscopic myotomy: Indications, technique, outcomes, and future directions

Amol Bapaye,Nachiket A. Dubale 소화기인터벤션의학회 2020 International journal of gastrointestinal interven Vol.9 No.2

After the clinical success of per-oral endoscopic myotomy (POEM) for treatment of achalasia cardia, the principle of submucosal tunneling and mucosal flap valve has been used in several other areas of the gastrointestinal tract. Gastric per-oral endoscopic pyloromyotomy (G-POEM, POEP, POP) is a relatively new procedure described for the treatment of refractory gastroparesis. This review discusses the indications, patient selection, pre-procedure workup, and procedure details of G-POEM. It also reviews the current literature on this procedure and provides insights and future directions for research on this topic.