One-step facile route to copper cobalt sulfide electrodes for supercapacitors with high-rate long-cycle life performance

Ahmed, Abu Talha Aqueel,Chavan, Harish S.,Jo, Yongcheol,Cho, Sangeun,Kim, Jongmin,Pawar, S.M.,Gunjakar, Jayavant L.,Inamdar, Akbar I.,Kim, Hyungsang,Im, Hyunsik Elsevier 2017 Journal of alloys and compounds Vol.724 No.-

<P><B>Abstract</B></P> <P>The impressive electrochemical energy storage performance of Earth-abundant ternary copper cobalt sulfide (CCS) thin film electrodes that are prepared on stainless steel substrates via a simple and cost-effective hydrothermal process is demonstrated. The optimized CCS electrode shows a high specific capacitance of ∼516 F/g at a current density of 10 A/g, a good rate capability of ∼72% at a high current density of 50 A/g, and a good cycling retention of ∼66% with a coulombic efficiency of ∼99% after 10,000 charge-discharge cycles. The CCS electrode exhibits a high energy density of ∼35.2 Wh/kg at a power density of ∼6.6 kW/kg. The excellent electrochemical supercapacitor properties of the CCS electrode are a result of a synergetic effect between the uniform full coverage, robust adhesion, and desired chemical composition. A low charge transfer resistance, resulting from the large electrochemically active surface area (ECSA) and good diffusion, significantly contributes to the enhanced electrochemical supercapacitor performance. This excellent CCS electrode material has the potential to become a low-cost and long-cycle life electrode for the next-generation high-power-capacity supercapacitors.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A binder-free CuCo<SUB>2</SUB>S<SUB>4</SUB> electrode is synthesized using one-pot hydrothermal deposition. </LI> <LI> Superior electrochemical energy storage-deliver performance is demonstrated. </LI> <LI> High specific capacitance, excellent rate performance, and high rate long-term cyclic stability are obtained. </LI> </UL> </P>

Influence of operating temperature on Li₂ZnTi₃O₈ anode performance and high-rate charging activity of Li-ion battery

Inamdar, Akbar I.,Ahmed, Abu Talha Aqueel,Chavan, Harish S.,Jo, Yongcheol,Cho, Sangeun,Kim, Jongmin,Pawar, Sambhaji M.,Hou, Bo,Cha, SeungNam,Kim, Hyungsang,Im, Hyunsik Elsevier 2018 CERAMICS INTERNATIONAL Vol.44 No.15

<P><B>Abstract</B></P> <P>The temperature-dependent performance of a Li<SUB>2</SUB>ZnTi<SUB>3</SUB>O<SUB>8</SUB> (LZTO) anode and the ultrafast-charging activity of a Li-ion battery were investigated. The LZTO anode operates at different temperatures between − 5 and 55 °C and in this work its sustainability is discussed in terms of storage performance. It delivered a discharge capacity of 181.3 mA h g<SUP>−1</SUP> at 25 °C, which increased to 227.3 mA h g<SUP>−1</SUP> at 40 °C and 131.2 mA h g<SUP>−1</SUP> at − 5 °C. The variation in the discharge capacity with temperature is associated with the reaction kinetics and the change in internal resistance. It showed a capacity retention of 64% and a coulombic efficiency of 98% over 500 cycles. Exhibiting a discharge capacity of 107 mA h g<SUP>−1</SUP>, the LZTO anode was sustainable over 100 charge-discharge cycles at an ultra-high charging rate of 10 Ag<SUP>−1</SUP>. The reaction kinetics estimated from a cyclic voltammetry analysis at high scan rates revealed a capacitive-type storage mechanism.</P> <P><B>Graphical abstract</B></P> <P>We developed an ultrafast rechargeable Li<SUB>2</SUB>ZnTi<SUB>3</SUB>O<SUB>8</SUB> (LZTO) anode for lithium-ion batteries. A half-cell LZTO battery delivered the highest reversible first discharge capacity of 181.3 mA h g<SUP>−1</SUP> at a current rate of 0.1 Ag<SUP>−1</SUP> and the maximum capacity of 106.97 mA h g<SUP>−1</SUP> was obtained when charged at an ultrafast charging rate of 10.0 Ag<SUP>−1</SUP>. The LZTO showed an excellent capacity-retention of 106.28%, suggesting excellent electrode sustainability, even at ultra-high-charging rates.</P> <P>[DISPLAY OMISSION]</P>

Nanoflake NiMoO₄ based smart supercapacitor for intelligent power balance monitoring

Chavan, Harish S.,Hou, Bo,Ahmed, Abu Talha Aqueel,Jo, Yongcheol,Cho, Sangeun,Kim, Jongmin,Pawar, Sambhaji M.,Cha, SeungNam,Inamdar, Akbar I.,Im, Hyunsik,Kim, Hyungsang North-Holland 2018 Solar energy materials and solar cells Vol.185 No.-

<P><B>Abstract</B></P> <P>A supercapacitor is well recognized as one of emerging energy sources for powering electronic devices in our daily life. Although various kind of supercapacitors have been designed and demonstrated, their market aspect could become advanced if the utilisation of other physicochemical properties (e.g. optical) is incorporated in the electrode. Herein, we present an electrochromic supercapacitor (smart supercapacitor) based on a nanoflake NiMoO<SUB>4</SUB> thin film which is fabricated using a facile and well-controlled successive ionic layer adsorption and reaction (SILAR) technique. The polycrystalline nanoflake NiMoO<SUB>4</SUB> electrode exhibits a large electrochemically active surface area of ~ 96.3 cm<SUP>2</SUP>. Its nanoporous architecture provides an easy pathway for the intercalation and de-intercalation of ions. The nanoflake NiMoO<SUB>4</SUB> electrode is dark-brown in the charged state and becomes transparent in the discharged state with a high optical modulation of 57%. The electrode shows a high specific capacity of 1853 Fg<SUP>–1</SUP> at a current rate of 1 Ag<SUP>–1</SUP> with a good coloration efficiency of 31.44 cm<SUP>2</SUP>/C. Dynamic visual information is obtained when the electrode is charged at different potentials, reflecting the level of energy storage in the device. The device retains 65% capacity after 2500 charge-discharge cycles compared with its initial capacity. The excellent performance of the nanoflake NiMoO<SUB>4</SUB> based smart supercapacitor is associated with the synergetic effect of nanoporous morphology with a large electrochemically active surface area and desired chemical composition for redox reaction.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A smart device with the combined advantages of energy storage and electrochromism is presented. </LI> <LI> It is dark-brown in the charged state and transparent in the discharged state. </LI> <LI> It exhibits a coloration efficiency of ~31.44 cm<SUP>2</SUP>/C and optical modulation of 57% at 630 nm. </LI> <LI> It shows specific capacity of 1853 F/g, with 65% capacity retention after 2500 cycles. </LI> </UL> </P>

Nanograin tungsten oxide with excess oxygen as a highly reversible anode material for high-performance Li-ion batteries

Inamdar, Akbar I.,Chavan, Harish.S.,Ahmed, Abu Talha Aqueel,Cho, Sangeun,Kim, Jongmin,Jo, Yongcheol,Pawar, Sambhaji M.,Park, Youngsin,Kim, Hyungsang,Im, Hyunsik North-Holland 2018 Materials Letters Vol. No.

<P><B>Abstract</B></P> <P>Nanogranular tungsten oxide (WO<SUB>3</SUB>) with excess oxygen is synthesized and its battery performance is evaluated as an anode material for the Li-ion battery (LIB). The formation of a monoclinic WO<SUB>3</SUB> phase is confirmed using X-ray diffraction (XRD) and micro (µ)-Raman spectroscopy analyses. The Rutherford back scattering results confirm the existence of excess oxygen in the film. The charge discharge processes are associated with the conversion of the WO<SUB>3</SUB> from the oxide state to the metallic state, and vice versa, and it shows a maximum specific capacity of 778.8 mAh g<SUP>−1</SUP> at a current density of 0.1 Ag<SUP>−1</SUP> in the first discharge. Even at a very high current density of 1 Ag<SUP>−1</SUP>, the sample retains the capacity of 228.6 mAh g<SUP>−1</SUP>. It shows excellent rate capability and a long-term cycling stability over 500 charge–discharge cycles, with capacity retention of 217%. The observed high discharge capacity and superior long-term cyclability of the nanograin WO<SUB>3</SUB> anode are attributable to the synergetic effect of the excess-oxygen induced increased donor density and enhanced electrical conductivity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Nanogranular WO<SUB>3</SUB> with excess oxygen is synthesized as an anode material for LIB. </LI> <LI> A maximum specific capacity of ∼779 mAh g<SUP>−1</SUP> and excellent rate capability are observed. </LI> <LI> Long-term cycling stability over 500 charge–discharge cycles with high capacity retention of 217% is obtained. </LI> <LI> Capacity retention of ∼229 mAh g<SUP>−1</SUP> at a very high current density of 1 Ag<SUP>−1</SUP> is achieved. </LI> </UL> </P>

Ultrathin Ni-Mo oxide nanoflakes for high-performance supercapacitor electrodes

Chavan, Harish S.,Hou, Bo,Ahmed, Abu Talha Aqueel,Kim, Jongmin,Jo, Yongcheol,Cho, Sangeun,Park, Youngsin,Pawar, Sambhaji M.,Inamdar, Akbar I.,Cha, Seung Nam,Kim, Hyungsang,Im, Hyunsik Elsevier 2018 Journal of Alloys and Compounds Vol.767 No.-

<P><B>Abstract</B></P> <P>Supercapacitors based on nanomaterial electrodes exhibit great potential as power sources for advanced electronic devices. From a practical viewpoint, it is desirable to fabricate highly active and sustainable nanomaterial electrodes consisting of non-precious elements using a simple technique in a controllable way. In this work, we report the synthesis of a self-assembled ultra-thin porous nanoflake Ni-Mo oxide (NMO) film using the successive ionic layer adsorption and reaction (SILAR) technique. The nanoflake NMO thin film electrode with a large electrochemically active surface area of ∼108 cm<SUP>−2</SUP> exhibits a high specific capacitance of 1180 Fg<SUP>−1</SUP> at a current density of 1 Ag<SUP>−1</SUP> and excellent rate capability, with a negligible capacity loss of 0.075% per cycle. Even at a high current rate of 10 A g<SUP>−1</SUP> it retains a capacity of 600 Fg<SUP>−1</SUP>. The highest energy and power densities obtained are 119 Whkg<SUP>−1</SUP> and 15.7 kWkg<SUP>−1</SUP>, respectively. Electrochemical impedance spectroscopy analyses reveal that the electrode has considerably low charge transfer resistance. The observed excellent electrochemical energy storage performance of the nanoflake NMO electrode with a nanoporous surface is due to the synergetic effects of the large electrochemically active surface area, enhanced ion diffusion, and improved electrical conductivity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ultra-thin porous Ni-Mo oxide nanoflakes self-assemble on stainless steel via a SILAR method. </LI> <LI> Large electrochemically-active surface area, enhanced ion diffusion and robust adhesion result in superior performance. </LI> <LI> High specific capacitance of 1180 F/g and energy density of 119 Wh/kg at 1 A/g are achieved. </LI> </UL> </P>

Bendable RuO₂/graphene thin film for fully flexible supercapacitor electrodes with superior stability

Cho, Sangeun,Kim, Jongmin,Jo, Yongcheol,Ahmed, Abu Talha Aqueel,Chavan, H.S.,Woo, Hyeonseok,Inamdar, A.I.,Gunjakar, J.L.,Pawar, S.M.,Park, Youngsin,Kim, Hyungsang,Im, Hyunsik ELSEVIER SCIENCE 2017 JOURNAL OF ALLOYS AND COMPOUNDS Vol.725 No.-

<P><B>Abstract</B></P> <P>Ruthenium oxide (RuO<SUB>2</SUB>) is fabricated on graphene (Gr)-coated Copper (Cu) foil by using a cathodic electroplating technique for flexible supercapacitor electrode applications. The electrochemical properties of the RuO<SUB>2</SUB>/Gr/Cu electrode are investigated with a conventional three electrode configuration in 0.5 M H<SUB>2</SUB>SO<SUB>4</SUB> electrolyte. The graphene insertion layer plays a key role in improving the structural and electrochemical properties of the RuO<SUB>2</SUB> electrode film under the bent condition. The electrode exhibits a specific capacitance of 1561 F g<SUP>−1</SUP> (0.015 F cm<SUP>−1</SUP>) at a scan rate of 5 mV s<SUP>−1</SUP> and a significantly improved retention of 98% under the bent condition. The flexible RuO<SUB>2</SUB>/Gr/Cu electrode exhibits a high energy density of ∼13 Wh kg<SUP>−1</SUP> at a power density of ∼21 kW kg<SUP>−1</SUP>. The excellent capacitance retention and electrochemical stability of the flexible RuO<SUB>2</SUB>/Gr/Cu electrode are due to the improved mechanical adhesion between the RuO<SUB>2</SUB> and the current collector. This flexible RuO<SUB>2</SUB>/Gr/Cu film could be used as a supercapacitor electrode with a high capacity and long-cycle life for the next-generation flexible electronic applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A binder-free Bendable RuO<SUB>2</SUB> thin film is fabricated on a graphene/Cu substrate using an electroplating method. </LI> <LI> Electrochemical energy storage properties of RuO<SUB>2</SUB> are investigated for supercapacitor applications. </LI> <LI> Excellent capacitance retention and electrochemical stability are obtained. </LI> </UL> </P>

Nanoporous CuCo₂O₄ nanosheets as a highly efficient bifunctional electrode for supercapacitors and water oxidation catalysis

Pawar, Sambhaji M.,Pawar, Bharati S.,Babar, Pravin T.,Ahmed, Abu Talha Aqueel,Chavan, Harish S.,Jo, Yongcheol,Cho, Sangeun,Kim, Jongmin,Hou, Bo,Inamdar, Akbar I.,Cha, SeungNam,Kim, Jin Hyeok,Kim, Tae Elsevier 2019 APPLIED SURFACE SCIENCE - Vol.470 No.-

<P><B>Abstract</B></P> <P>Efficient and low‐cost multifunctional electrodes play a key role in improving the performance of energy conversion and storage devices. In this study, ultrathin nanoporous CuCo<SUB>2</SUB>O<SUB>4</SUB> nanosheets are synthesized on a nickel foam substrate using electrodeposition followed by air annealing. The CuCo<SUB>2</SUB>O<SUB>4</SUB> nanosheet electrode exhibits a high specific capacitance of 1473 F g<SUP>─1</SUP> at 1 A g<SUP>─1</SUP> with a capacity retention of ∼93% after 5000 cycles in 3 M KOH solution. It also works well as an efficient oxygen evolution reaction electrocatalyst, demonstrating an overpotential of 260 mV at 20 mA cm<SUP>─2</SUP> with a Tafel slope of ∼64 mV dec<SUP>─1</SUP>. in 1 M KOH solution, which is the lowest reported among other copper-cobalt based transition metal oxide catalysts. The catalyst is very stable at >20 mA cm<SUP>─2</SUP> for more than 25 h. The superior electrochemical performance of the CuCo<SUB>2</SUB>O<SUB>4</SUB> nanosheet electrode is due to the synergetic effect of the direct growth of 2D nanosheet structure and a large electrochemically active surface area associated with nanopores on the CuCo<SUB>2</SUB>O<SUB>4</SUB> nanosheet surface.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ultrathin nanoporous CuCo<SUB>2</SUB>O<SUB>4</SUB> nanosheets electrode synthesized by electrodeposition. </LI> <LI> High specific capacitance and good cycling stability were obtained. </LI> <LI> Highly efficient OER electrocatalyst with an overpotential of 260 mV at 20 mA/cm<SUP>2</SUP>. </LI> <LI> Excellent long-term electrochemical durability. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Calcium nitrate (Ca(NO₃)₂)-based inorganic salt electrode for supercapacitor with long-cycle life performance

Cho, S.,Han, J.,Kim, J.,Jo, Y.,Woo, H.,Lee, S.,Aqueel Ahmed, A.T.,Chavan, H.C.,Pawar, S.M.,Gunjakar, J.L.,Kwak, J.,Park, Y.,Inamdar, A.I.,Kim, H.,Kim, H.,Im, H. ELSEVIER 2017 CURRENT APPLIED PHYSICS Vol.17 No.9

<P>A novel water-soluble inorganic Ca(NO3)(2) salt electrode is investigated for its pseudocapacitance in an aqueous KOH electrolyte. Commercially available Ca(NO3)(2) salt is directly used as the key electrode material. The supercapacitor electrode contains Ca(NO3)(2) salt, carbon black, and polyvinylidene fluoride (PVDF) in a ratio of 80:10:10. The Ca(NO3)(2)-based electrode demonstrates an exceptionally long life cycling stability, and a reasonably sound specific capacitance of 234 F/g is obtained at a current density of 3 A/g. Via chemical and electrochemical reactions, the in-situ activation of the Ca(NO3)(2) forms an intermediate CaO which contributes to the pseudocapacitance of the electrode. The electrode undergoes a reversible redox reaction between Cu2+ <-> Cu+ during the charge-discharge process. Superior rate capability and excellent specific capacitance retention of similar to 120% over 2000 cycles are achieved compared with other inorganic salt electrodes. (C) 2017 Elsevier B.V. All rights reserved.</P>

Calcium nitrate (Ca(NO3)2)-based inorganic salt electrode for supercapacitor with long-cycle life performance

조상은,한재석,김종민,조용철,우현석,이성우,ABU TALHA AQUEEL AHMED,Harish C. Chavan,S.M. Pawar,Jayavant L. Gunjakar,곽정원,박영신,Akbar I. Inamdar,김현정,김형상,임현식 한국물리학회 2017 Current Applied Physics Vol.17 No.9

A novel water-soluble inorganic Ca(NO3)2 salt electrode is investigated for its pseudocapacitance in an aqueous KOH electrolyte. Commercially available Ca(NO3)2 salt is directly used as the key electrode material. The supercapacitor electrode contains Ca(NO3)2 salt, carbon black, and polyvinylidene fluoride (PVDF) in a ratio of 80:10:10. The Ca(NO3)2-based electrode demonstrates an exceptionally long life cycling stability, and a reasonably sound specific capacitance of 234 F/g is obtained at a current density of 3 A/g. Via chemical and electrochemical reactions, the in-situ activation of the Ca(NO3)2 forms an intermediate CaO which contributes to the pseudocapacitance of the electrode. The electrode undergoes a reversible redox reaction between Cu2þ 4 Cuþ during the charge-discharge process. Superior rate capability and excellent specific capacitance retention of ~120% over 2000 cycles are achieved compared with other inorganic salt electrodes.

Self-assembled two-dimensional copper oxide nanosheet bundles as an efficient oxygen evolution reaction (OER) electrocatalyst for water splitting applications

Pawar, Sambhaji M.,Pawar, Bharati S.,Hou, Bo,Kim, Jongmin,Aqueel Ahmed, Abu Talha,Chavan, Harish. S.,Jo, Yongcheol,Cho, Sangeun,Inamdar, Akbar I.,Gunjakar, Jayavant L.,Kim, Hyungsang,Cha, SeungNam,Im, The Royal Society of Chemistry 2017 Journal of materials chemistry. A, Materials for e Vol.5 No.25

<P>A high activity of a two-dimensional (2D) copper oxide (CuO) electrocatalyst for the oxygen evolution reaction (OER) is presented. The CuO electrode self-assembles on a stainless steel substrate<I>via</I>chemical bath deposition at 80 °C in a mixed solution of CuSO4and NH4OH, followed by air annealing treatment, and shows a 2D nanosheet bundle-type morphology. The OER performance is studied in a 1 M KOH solution. The OER starts to occur at about 1.48 V<I>versus</I>the RHE (<I>η</I>= 250 mV) with a Tafel slope of 59 mV dec<SUP>−1</SUP>in a 1 M KOH solution. The overpotential (<I>η</I>) of 350 mV at 10 mA cm<SUP>−2</SUP>is among the lowest compared with other copper-based materials. The catalyst can deliver a stable current density of >10 mA cm<SUP>−2</SUP>for more than 10 hours. This superior OER activity is due to its adequately exposed OER-favorable 2D morphology and the optimized electronic properties resulting from the thermal treatment.</P>