Self-Generated Nanoporous Silver Framework for High-Performance Iron Oxide Pseudocapacitor Anodes

Seok, Jae Young,Lee, Jaehak,Yang, Minyang American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.20

<P>The rapid development of electric vehicles is increasing the demand for next-generation fast-charging energy storage devices with a high capacity and long-term stability. Metal oxide/hydroxide pseudocapacitors are the most promising technology because they show a theoretical capacitance that is 10-100 times higher than that of conventional supercapacitors and rate capability and long-term stability that are much higher than those of Li-ion batteries. However, the poor electrical conductivity of metal oxides/hydroxides is a serious obstacle for achieving the theoretical pseudocapacitor performance. Here, a nanoporous silver (np-Ag) structure with a tunable pore size and ligament is developed using a new silver halide electroreduction process. The structural characteristics of np-Ag (e.g., large specific surface area, electric conductivity, and porosity) are desirable for metal oxide-based pseudocapacitors. This work demonstrates an ultra-high-capacity, fast-charging, and long-term cycling pseudocapacitor anode via the development of an np-Ag framework and deposition of a thin layer of Fe<SUB>2</SUB>O<SUB>3</SUB> on its surface (np-Ag@Fe<SUB>2</SUB>O<SUB>3</SUB>). The np-Ag@Fe<SUB>2</SUB>O<SUB>3</SUB> anode shows a capacitance of ∼608 F g<SUP>-1</SUP> at 10 A g<SUP>-1</SUP>, and ∼84.9% of the capacitance is retained after 6000 charge-discharge cycles. This stable and high-capacity anode, which can be charged within a few tens of seconds, is a promising candidate for next-generation energy storage devices.</P> [FIG OMISSION]</BR>

Pliable and stable high-energy all-solid-state asymmetric pseudocapacitor with ultrahigh mass loaded 2D electrodes

( 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 MnO₂ (MnO₂@CF, 6.6 mg/㎠) and MoS₂ (MoS₂@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 MnO₂@CF and MoS₂@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.

α-MnO2 nanorod/boron nitride nanoplatelet composites for high-performance nanoscale dielectric pseudocapacitor applications

Hasi Rani Barai,Mohammad Mahbubur Rahman,Abdur Rahim,주상우 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.79 No.-

We demonstrate the synthesis of a composite of α-MnO2 nanorods and dielectric boron nitridenanoplatelets(BNNPs) as an electrode material for application in nanoscale dielectric pseudocapacitors. The optimize nanocomposite delivers a significantly high specific capacitance (890 F/g at 0.41 A/g), whichis >72% of the theoretical specific capacitance of α-MnO2 at a mass loading of ca. 6 wt%. Pure BNNPsexhibit negligible charge storage capacity with a specific capacitance of 1.30 F/g at 0.024 A/g. The BNNPsincrease the amount of K+ insertion/extraction and the conductivity of α-MnO2 nanorods by lowering thecharge transfer resistance at the electrode-electrolyte interface. This is due to the electrical polarizationof dielectric BNNPs during charging and discharging, which increases the rate and amount of K+ insertionor extraction induce by electrostatic force. The nanocomposite shows good capacity retention (94.12%after 2000 cycles) with high energy and power density. This research opens up a new avenue for thedevelopment of new types of nanoscale dielectric pseudocapacitors with high capacitance by exploringother suitable metal-oxides and nanoscale dielectric material composites.

Development of High-Capacity Pseudocapacitor based on Graphene/Nickel Oxide hybrid Nanocomposites

정민규,박호석 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0

Among many types of energy storage devices, supercapacitors have played an important role in various fields due to the advantage of high power density and long cycle life. By the way, conventional EDLC type supercapacitors have some limitations for wide usage because of low energy density. Here, to overcome this problem, Graphene/Nickel Oixde hybrid composite has been considered as a promising electrode material for realizing ultra-high capacity pseudocapacitor. since the carbon nanotube branches are growth directly on the surface of the carbon nanotube or graphene, excellent interface characteristics can be realized and 3D carbon structure can be obtained in a short time due to microwave synthesizing method. Therefore, it has a lot of advantages in term of practical use. In this work, we present the synthesis method, unique structure and physical properties of Nickel hybrid composites, as well as their electrochemical and related applications, and outlook for future research.

Systematic design of hierarchical Ni₃S₂/MoO₂ nanostructures grown on 3D conductive substrate for high-performance pseudocapacitors

Lee, Young-Woo,Kim, Min-Cheol,Nguyen, Quoc Hung,Ahn, Wook,Jung, Jae-Eun,Park, Kyung-Won,Sohn, Jung Inn Elsevier 2019 CERAMICS INTERNATIONAL Vol.45 No.2

<P><B>Abstract</B></P> <P>For high-performance pseudocapacitors, the rational design of nanoarchitectures has gained extensive attention to achieve superior pseudo-capacitive behaviors such as excellent energy storing ability and long-term cyclability. Here, we report systematically designed hierarchical Ni<SUB>3</SUB>S<SUB>2</SUB>/MoO<SUB>2</SUB> (H-Ni<SUB>3</SUB>S<SUB>2</SUB>/MoO<SUB>2</SUB>) nanostructures directly grown on a 3D conductive substrate via a facile one-step synthesis route. The synthesized H-Ni<SUB>3</SUB>S<SUB>2</SUB>/MoO<SUB>2</SUB> exhibits a high specific capacitance of 1376.1 F g<SUP>−1</SUP> at 1 mA cm<SUP>−2</SUP>, a high energy density of 45.9 Wh kg<SUP>−1</SUP>, and a good capacitance retention of 86.0% during 2000 cycles. These enhanced pseudo-capacitive features of H-Ni<SUB>3</SUB>S<SUB>2</SUB>/MoO<SUB>2</SUB> are attributed to their unique nanoarchitectures favorable for pseudo-capacitive behavior as follows: (1) densely arrayed Ni<SUB>3</SUB>S<SUB>2</SUB> nanoarchitectures consisting of the primary 1D nanowires and the secondary 2D nanosheets providing large electrolyte contact areas that can increase specific capacitances, and (2) well-engineered interfacial layer of MoO<SUB>2</SUB> that can induce good electrochemical cyclability. Thus, our results suggest that the H-Ni<SUB>3</SUB>S<SUB>2</SUB>/MoO<SUB>2</SUB> can be utilized as a promising pseudo-capacitive electrode for high-performance pseudocapacitors.</P>

HMTA-assisted uniform cobalt ions activated copper oxide microspheres with enhanced electrochemical performance for pseudocapacitors

Hussain, Sk. Khaja,Yu, Jae Su Pergamon Press 2017 Electrochimica Acta Vol. No.

<P><B>Abstract</B></P> <P>Supercapacitors are being considered to be one of important electrochemical energy storage devices due to their high power density as compared with batteries and have remarkable applications. The large surface area transition metal oxides or hydroxides are excellent conductive materials and have been extensively used for supercapacitors. Herein, uniform copper oxide (CuO) and cobalt (Co) activated CuO (CuO:Co) microspheres were synthesized by a hexamethylenetetramine (HMTA)-assisted hydrothermal method. The HMTA was used as an additive surfactant to acquire the uniform microsphere morphology, which was confirmed by high-resolution field-emission scanning electron microscope and field-emission transmission electron microscope images. The phase form of the pristine CuO and CuO:Co powder samples was examined by X-ray diffraction patterns. For the application of pseudocapacitors, electrochemical studies were performed for the CuO and CuO:Co electrode materials in a three-electrode electrochemical cell system. The cyclic voltammetry and galvanostatic charge-discharge curves were measured at different scan rates and current densities, respectively, in 1 M KOH electrolyte solution. The calculated specific capacitance values of the CuO and CuO:Co electrodes were 77 and 284 F/g at a current density of 1 A/g, respectively. Interestingly, by incorporating small concentration of Co into CuO, the specific capacitance was enhanced approximately 4 times when compared with the pristine CuO electrode. The electrochemical impedance spectroscopy spectrum was analyzed for the pseudocapacitive behavior of CuO:Co electrode material. Furthermore, the CuO:Co electrode showed a capacitance retention (75.6%) after 1000 cycles at a current density of 3 A/g. Therefore, the obtained remarkable electrochemical results suggest that the low-cost CuO:Co electrode materials with improved electrochemical performance have promising applications in the field of pseudocapacitors.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CuO and Co doped CuO uniform microspheres were synthesized by a hydrothermal method. </LI> <LI> The specific capacitance of pristine CuO was enhanced by doping Co into CuO. </LI> <LI> The CuO:Co electrode exhibited good cycling stability. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Two-Dimensional Cobalt-Based Composites Grown on Ti Plates for Application as Pseudocapacitor Materials

주용택,조민영,박선민,백성현,이철태,노광철 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.4

Various cobalt-based composites grown on Ti plates were synthesized using electrochemical precipitation by controlling pH. For all samples, peaks associated with Co3O4, CoOOH, and Co(OH)2 were found in the XRD spectra for the cobalt-based composites. The morphologies of the cobalt oxide/hydroxide exhibited a mixture of 2D hexagonal platelets. The pseudocapacitive properties of cobalt-based composites were investigated using cyclic voltammetry (CV) in a 1M KOH electrolyte solution. Oxidation and reduction peak currents were measured during cycling between −0.2 and 0.4 V (vs. a saturated calomel electrode). The Co3O4/Co(OH)2electrode synthesized at pH 6.5 exhibited a maximum specific capacitance of 627 F g−1. The results suggest that the use of cobalt-based composites is an effective strategy for producing high energy pseudocapacitors.

Cubic Spinel AB₂O₄ Type Porous ZnCo₂O₄ Microspheres: Facile Hydrothermal Synthesis and Their Electrochemical Performances in Pseudocapacitor

Rajesh, John Anthuvan,Min, Bong-Ki,Kim, Jae-Hong,Kim, Hyunsoo,Ahn, Kwang-Soon The Electrochemical Society 2016 Journal of the Electrochemical Society Vol.163 No.10

<P>Microspheres of cubic spinel ZnCo2O4 were synthesized using a facile ethylene glycol-mediated hydrothermal method. The size and crystallinity of the ZnCo2O4 microspheres were tuned by simply varying the reaction times. The as-synthesized ZnCo2O4 microspheres had porous structures that were constructed by numerous small building blocks of primary nanoparticles, leading to the formation of sphere-like morphology. The ZnCo2O4 microspheres exhibited a large surface area of 37.27 m(2) g(-1) with mesopores, 24.66 nm in size, resulting in significantly enhanced electrochemical activity toward pseudocapacitors. Remarkably, the as-made ZnCo2O4 microspheres electrode delivered a high specific capacitance (853.6 F g(-1) at a current density of 2 A g(-1)), good rate performance (417.1 F g(-1) at 10 A g(-1)) and excellent cyclic stability (92.7% capacitance retention after 3000 cycles at a current density of 10 A g(-1)). Moreover, a symmetric supercapacitor based on ZnCo2O4 microsphere electrodes achieved an energy density of 11.8 Wh kg(-1) and a maximum power density of 2.5 kW kg(-1). The good electrochemical performances can be attributed to the unique porous microsphere texture, high surface area and good electrical conductivity due to the synergistic effect between the two metal elements. (C) 2016 The Electrochemical Society. All rights reserved.</P>

Cost-Effective Fabrication of Biomorphic Mesoporous Ni-NiO Microtube for Pseudocapacitors

Binbin Chang,Hang Yin,Zhengyan Gu,Zhikun Li,Baocheng Yang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.11

In this paper, a biomorphic mesoporous Ni-NiO microtube was successfully prepared by a facile and cost-effective synthesis strategy using cotton as a biotemplate. The morphology and textural characterization of as-obtained Ni-NiO materials were analyzed by X-ray diffraction patterns, scanning electron microscopy and nitrogen adsorption–desorption technology. The results suggested the as-prepared Ni-NiO samples owned uniform micro-tubular morphology and prominent mesoporous structure. Meanwhile, the effect of annealing temperature on morphology and porosity of Ni-NiO was also investigated. The optimal sample, Ni-NiO-4, exhibited a uniform microtube morphology with an ideal mesoporous structure of a high surface area (15.8 m2 g-1) and suitable mesopore size (9.28 nm). Furthermore, these as-obtained Ni-NiO materials showed enhanced electrochemical property as electrodes for pseudocapacitors. Especially, the Ni-NiO-4 electrode displayed the outstanding capacitive performance, including a high specific capacitance of 98.7 F g-1 at 0.5 A g-1 and satisfactory rate capacity. More importantly, Ni-NiO-4 electrode owned an excellently long-term cycling stability.

Synthesis and Characterization of Poly(3,4-ethylene dioxythiophene)/Ammonium Vanadate Nanofiber Composites for High Pseudocapacitive Performance

이세훈,박창용,임승순,안희준 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0

Vanadium oxide has attracted a lot of attention in energy storage applications due to their intercalation properties by layered structure, effective electronic properties by multiple valences. However, since the electrical conductivity of vanadium oxide itself does not meet the requirements for electrode materials. In this study, PEDOT-intercalated ammonium vanadate nanofiber composites (S-EANVF) were synthesized within 3 hrs by using the sonochemical method. When the S-EAVNF was applied as an electrode material for pseudocapacitors, the crystal lattice distance of the vanadate nanofiber expanded by the PEDOT intercalation allowed the K+ ions of the electrolyte to rapidly diffuse between the lattice layers of the vanadate nanofiber, improving the charge storage capacitance and rate capability of the pseudocapacitor. Therefore, the proposed nanofiber composites can lead to new research directions in the field of high-rate energy storage devices.