수열합성된 나노구조 니켈/니켈 수산화물의 상과 형태 및 슈퍼커패시터 적용

엄승용,정진주,김도형 한국물리학회 2021 새물리 Vol.71 No.6

Urchin-like nanostructured nickel/nickel hydroxides (NNHO) were successfully synthesized by using the hydrothermal method, and the phase and the morphology of the nanostructured nickel/nickel hydroxide were controlled by using different synthesis temperatures. The diameter of the nanostructured NNHO synthesized at a relatively high temperature wes bigger than that of the samples synthesized at low temperature, which could be explained by using Ostwald ripening. The phase of the as-synthesized nanostructure was composed of crystalline metallic nickel on the inside and amorphous nickel hydroxide on the surface. To compare the electrochemical properties, the as-synthesized samples are converted to nickel oxide (NO) by annealing at different temperatures. The as-synthesized NNHO showed the highest specific capacitance, as well as easy electrolyte accessibility, because NNHO had not only an easily accessible nanostructure but also the synergistic effect of crystalline nickel and amorphous nickel hydroxide. The present work can contribute to the synthesis of nanostructured NNHO and to the applications of supercapacitors using heterostructure materials. 성게 모양의 나노구조 니켈/니켈 수산화물(NNHO)을 수열합성법으로 합성하였다. 나노구조 NNHO의상과 형태는 합성 온도와 합성 후 열처리 온도에 의해 조절되었다. 상대적으로 고온에서 합성된 나노구조NNHO의 직경은 저온에서 합성된 샘플보다 직경이 크고, 이는 오스트발트 숙성 (Ostwald ripening)에의해 설명된다. 합성된 나노구조 NNHO의 상은 내부의 결정성 금속 니켈과 표면의 비정질 니켈 수산화물로구성된다. 전기화학적 특성을 비교하기 위해, 합성된 NNHO를 열처리하여 니켈 산화물(NO)로 상전이시켰다. 순환전압전류법 및 정전류 충방전 측정 결과, 합성된 NNHO가 NO에 비해서 더 높은 전기용량과쉬운 전해질 접근성을 보였으며, 이것은 NNHO가 쉽게 접근 가능한 나노구조를 가질 뿐만 아니라 결정질니켈과 비결정질 니켈 수산화물의 시너지 효과 (synergistic effect) 에 의한 것이다. 이 연구는 나노구조 NNHO의 합성과 이종 구조 물질을 활용한 슈퍼커패시터 응용 연구에 기여할 수 있을 것으로 기대된다.

니켈수소전지용 수산화니켈 입자의 표면처리와 전해액 첨가제 LiOH의 전기화학적 거동

김호성,오익현,Kim, Ho-Sung,Oh, Ik-Hyun 한국전기화학회 2008 한국전기화학회지 Vol.11 No.2

본 논문은 니켈수소전지의 양극 재료인 수산화니켈의 단일 입자 및 코발트 금속산화물에 의해 표면처리 된 수산화니켈 단일 입자에 대해 각각 알카리 전해액 중의 LiOH 첨가 효과를 마이크로전극 측정시스템을 사용하여 평가하였다. 전위 주사법에 의해 실험한 결과, 수산화니켈 입자에 대한 산화환원 반응과 산소발생 반응에 대한 전기화학적 거동을 보다 명확히 확인 할 수 있었다. 특히, LiOH 첨가에 의해 관찰되는 특징적인 변화는 환원전류 피크가 매우 낮고 브로드하게 반응하는 것으로서, LiOH가 수산화니켈 입자의 격정 구조에 영향을 주어 전기화학적 반응특성에 관여함을 알 수 있다. 그러나 표면 개질 하지 않는 수산화니켈 입자에 LiOH를 첨가 할 경우 용량 및 사이클 특성이 동시에 저하하는 경향을 의였다. 그러나 코발트 금속 산화물로 표면 개질 한 수산화니켈 입자의 경우, LiOH 첨가에 의해 용량 및 싸이클 특성이 향상되는 현상이 관찰 되었다. Single particle of nickel hydroxide and the surface-treated one with cobalt element were performed to review the effect of LiOH additive in alkaline electrolyte for Ni-MH batteries using microelectrode test system. As a result of cyclic voltammetry, the electrochemical behaviors such as the oxidation/reduction and oxygen evolution reaction are clearly observed for a single particle of nickel hydroxide, respectively. Furthermore, the reduction current peak of nickel hydroxide added with LiOH in electrolyte was very low and broad compared with the normal nickel hydroxide without an additive LiOH, which had a bad effect to the crystallization structure of nickel hydroxide. However, it was found that capacity and cycle properties of the nickel hydroxide treated with cobalt greatly increased by the addition of LiOH.

One-pot microwave-assisted synthesis of reduced graphene oxide/nickel cobalt double hydroxide composites and their electrochemical behavior

Kim, Y.,Cho, E.s.,Park, S.J.,Kim, S. Korean Society of Industrial and Engineering Chemi 2016 Journal of industrial and engineering chemistry Vol.33 No.-

<P>Reduced graphene oxide (RGO)/nickel cobalt (NiCo) double hydroxide composites were synthesized by one-pot microwave-assisted method in propylene carbonate. This method is efficient because the reduction of graphene oxide and the formation of hydroxide particles on the graphene sheets were simultaneously produced. We investigated an effect of microwave irradiation in organic solvent and an electrochemical influence of nickel and cobalt ratio in double hydroxide. Morphological characterization was performed by XRD, FTIR, XPS and FE-SEM. It was found that the NiCo double hydroxide particles were well decorated on the surface of RGO sheets and the reduction of graphene oxide was completed by short-term microwave irradiation. Electrochemical behavior was also measured by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge performance. The highest specific capacitance was 1622 F g(-1) obtained at (RGO)/NiCo 2:1 (weight ratio of nickel to cobalt was 2-1). Furthermore, the composites showed higher capacitance, as well as lower resistance, better rate capability and longer cycle life rather than RGO/Ni(OH)(2) and RGO/Co(OH)(2). (C) 2015 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.</P>

One-pot microwave-assisted synthesis of reduced graphene oxide/nickel cobalt double hydroxide composites and their electrochemical behavior

김유나,김석,조은삼,박수진 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.33 No.-

Reduced graphene oxide (RGO)/nickel cobalt (NiCo) double hydroxide composites were synthesized byone-pot microwave-assisted method in propylene carbonate. This method is efficient because thereduction of graphene oxide and the formation of hydroxide particles on the graphene sheets weresimultaneously produced. We investigated an effect of microwave irradiation in organic solvent and anelectrochemical influence of nickel and cobalt ratio in double hydroxide. Morphological characterizationwas performed by XRD, FTIR, XPS and FE-SEM. It was found that the NiCo double hydroxide particleswere well decorated on the surface of RGO sheets and the reduction of graphene oxide was completed byshort-term microwave irradiation. Electrochemical behavior was also measured by cyclic voltammetry(CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge performance. The highest specific capacitance was 1622 F g 1 obtained at (RGO)/NiCo 2:1 (weight ratio of nickel tocobalt was 2–1). Furthermore, the composites showed higher capacitance, as well as lower resistance,better rate capability and longer cycle life rather than RGO/Ni(OH)2 and RGO/Co(OH)2.

Nickel hydroxide/chemical vapor deposition-grown graphene/nickel hydroxide/nickel foam hybrid electrode for high performance supercapacitors

Liu, Shude,Yin, Ying,San Hui, Kwan,Hui, Kwun Nam,Lee, Su Chan,Chan Jun, Seong Elsevier 2019 ELECTROCHIMICA ACTA Vol.297 No.-

<P><B>Abstract</B></P> <P>Rational design of electrode structures has been recognized as an effective strategy to improve the electrochemical performance of electrode materials. Herein, we demonstrate an integrated electrode in which nickel hydroxide (Ni(OH)<SUB>2</SUB>) nanosheets are deposited on both sides of chemical vapor deposition-grown graphene on Ni foam, which not only effectively optimizes electrical conductivity of Ni(OH)<SUB>2</SUB>, but also accommodates the structural deformation associated with the large volume change upon cycling. The synthesized Ni(OH)<SUB>2</SUB>/graphene/Ni(OH)<SUB>2</SUB>/Ni foam electrode exhibits a high specific capacity of 991 C g<SUP>−1</SUP> at a current density of 1 A g<SUP>−1</SUP>, which is higher than the theoretical specific capacity of additive sum of Ni(OH)<SUB>2</SUB> and graphene, and retains 95.4% of the initial capacity after 5000 cycles. A hybrid supercapacitor is constructed by using Ni(OH)<SUB>2</SUB>/graphene/Ni(OH)<SUB>2</SUB>/Ni foam as the positive electrode and activated carbon on Ni foam as the negative electrode, which achieves a maximum energy density of 49.5 W h kg<SUP>−1</SUP> at a power density of 750 W kg<SUP>−1</SUP>, and excellent cycling lifespans with 89.3% retention after 10000 cycles at 10 A g<SUP>−1</SUP>.</P>

Electrochemical characteristics of nickel hydroxide/activated carbon nano composite for supercapacitors

Mok-Hwa Kim 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.S1

Nickel hydroxide/activated carbon nanocomposite electrode material was successfully synthesized by a precipitation method. The activated carbon was prepared from isotropic pitch with chemical and electrochemical activation. Structural and morphological characterizations were performed using X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), and high resolution transmission electron microscopy (HR-TEM). The capacitive properties were evaluated by cyclic voltammerty (CV), charge/discharge, and electrochemical impedance spectroscopy (EIS) in 6M KOH aqueous electrolyte. The results showed that nano-sized nickel hydroxide was loaded on the surface of activated carbon. A specific capacitance of 277.8 Fg-1 was obtained at a constant current of 1 mAcm-2, indicating that the nickel hydroxide/activated carbon nanocomposite is a promising electrode material for supercapacitors.

Nanostructured Ni-Mn double hydroxide for high capacitance supercapacitor application

( Rahul B. Pujari ),( Dong-weon Lee ) 한국센서학회 2021 센서학회지 Vol.30 No.2

Recently, transition-metal-based hydroxide materials have attracted significant attention in various electrochemical applications owing to their low cost, high stability, and versatility in composition and morphology. Among these applications, transition-metal-based hydroxides have exhibited significant potential in supercapacitors owing to their multiple redox states that can considerably enhance the supercapacitance performance. In this study, nanostructured Ni-Mn double hydroxide is directly grown on a conductive substrate using an electrodeposition method. Ni-Mn double hydroxide exhibits excellent electrochemical charge-storage properties in a 1 M KOH electrolyte, such as a specific capacitance of 1364 Fg^-1 at a current density of 1 mAcm^-2 and a capacitance retention of 94% over 3000 charge-discharge cycles at a current density of 10 mAcm^-2. The present work demonstrates a scalable, time-saving, and cost-effective approach for the preparation of Ni-Mn double hydroxide with potential application in high-charge-storage kinetics, which can also be extended for other transition-metal-based double hydroxides.

Effects of high electrical conductive agents on electrochemical behaviors of capacitive deionization

백진,이혜민,안계혁,이해성,김병주 한국공업화학회 2014 한국공업화학회 연구논문 초록집 Vol.2014 No.1

In this study, porous nickel hydroxide/carbon composite electrodes were prepared for capacitive deionization (CDI) electrode applications by mixing the porous nickel hydroxides with carboxymethyl cellulose, styrene butadiene rubber, and high electrical conductive carbon materials (VGCF, CNT, CB). Porous nickel hydroxides were synthesized by self-assembly of nickel nitrates and sodium dodecyl sulfate template under acidic conditions. And, composite electrodes were observed for high electrical conductive agents to enhance specific capacitance of CDI. The capacitive properties of the composite electrodes were investigated by cyclic voltammetry and galvanostatic charge-discharge methods in 1 M NaCl aqueous electrolyte, respectively.

Reverse micelle synthesis of colloidal nickel-manganese layered double hydroxide nanosheets and their pseudocapacitive properties

심환수,임병권 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1

Colloidal nanosheets of nickel-manganese layered double hydroxides (LDHs) have been synthesized in high yields through a facile reverse micelle method with xylene as an oil phase and oleylamine as a surfactant. Electron microscopy studies of the product revealed the formation of colloidal nanoplatelets with sizes of 50-150 nm, and X-ray diffraction, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy studies showed that the Ni-Mn LDH nanosheets had a hydrotalcite-like structure with a formula of [Ni₃Mn(OH)₈](C-l)·nH₂O. We found that the presence of both Ni and Mn precursors was required for the growth of Ni-Mn LDH nanosheets. As pseudocapacitors, the Ni-Mn LDH nanosheets exhibited much higher specific capacitance than unitary nickel hydroxides and manganese oxides.

Activation of a Ni electrocatalyst through spontaneous transformation of nickel sulfide to nickel hydroxide in an oxygen evolution reaction

Lee, Minoh,Oh, Hyung-Suk,Cho, Min Kyung,Ahn, Jae-Pyoung,Hwang, Yun Jeong,Min, Byoung Koun Elsevier 2018 Applied Catalysis B Vol.233 No.-

<P><B>Abstract</B></P> <P>Ni-sulfide compounds synthesized on Ni foam by simple thermal sulfurization are employed as electrocatalysts for water oxidation, resulting in superior activity in alkaline electrolyte media. The role of sulfur in Ni-sulfide was found to be an activator that transformed sulfide into hydroxide, which was eventually transformed into (oxy)hydroxide. The Ni-(oxy)hydroxide phase was also found to be layered and/or amorphous. This activated catalyst showed significant enhancement in water oxidation performance with a low overpotential value of 256 mV at current density of 10 mA cm<SUP>−2</SUP>. Our observation could offer important insight into metal-chalcogenide electrocatalyst for water oxidation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Electro-oxidation treatment on Ni-sulfide/Ni foam highly improves its OER activity. </LI> <LI> Sulfurization of Ni facilitates the formation of Ni-(oxy)hydroxide layer on the surface. </LI> <LI> Ni<SUB>3</SUB>S<SUB>2</SUB> derived amorphous/crystalline Ni-(oxy)hydroxide mixtures with Fe are active for OER. </LI> <LI> Sulfur in Ni<SUB>3</SUB>S<SUB>2</SUB> activates to form nanoparticle embedded layered structures in amorphous matrix. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>