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슈퍼커패시터 전극을 위한 니켈-몰리브덴 황화물 나노구조의 합성 및 전기화학적 특성 분석
Bhimanaboina Ramulu,S. Chandra Sekhar,Shaik Junied Arbaz,유재수 한국진공학회 2021 한국진공학회 학술발표회초록집 Vol.2021 No.2
최근 빠른 충방전 능력, 긴 사이클링 안정성 등의 우수한 특성을 갖는 슈퍼커패시터에 대한 관심이 증가하고 있다. 본 발표에서는 화학적 안정성, 저비용 및 향상된 전기화학적 성능을 가지는 니켈 몰리브데이트를 효율적인 전극제작을 위해 연구하였다. 인, 질소, 붕소 및 황과 같은 이종원자를 사용한 도핑공정은 호스트 물질의 전자상태를 효율적으로 조정하고 표면 wettability를 개선하며 활성결함을 생성할 수 있다. 여기서 수열합성법으로 니켈-몰리브덴 옥시-인화물과 옥시-황화물을 합성한 후 음이온 교환공정을 진행하여 전하수송을 촉진하는 나노구조를 형성하여 슈퍼커패시트 전극 제작을 통해 전기화학적 특성을 조사하였다.
금속몰리브데이트 초박형 나노시트기반 에너지 저장소자 제작 연구
Bhimanaboina Ramulu,S. Chandra Sekhar,Shaik Junied Arbaz,유재수 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.2
본 발표에서 자립형 나노구조 전극재료의 합리적인 설계는 높은 전력밀도를 가진 에너지 저장소자인 슈퍼커패시터의 전기화학적 성능을 향상시키는 효과적인 접근 방식이다. 여기에서는 단일 단계 용매 열공정을 통해 구리 폼에서 직접 성장한 금속몰리브데이트 초박형 나노시트의 손쉬운 합성을 설명한다. 제작된 샘플의 전기화학적 특성이 분석되었다.
Ramulu, Bhimanaboina,Nagaraju, Goli,Chandra Sekhar, S.,Hussain, Sk. Khaja,Narsimulu, D.,Yu, Jae Su American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.44
<P>Designing binder-free and core-shell-like electrode materials with synergistic effects has attracted widespread attention for the development of high energy density hybrid supercapacitors (HSCs). Herein, binder-free cobalt molybdate nanosheet-laminated cobalt phosphate micropetals on nickel foam (CoM NS@CoP/NF) were facilely prepared for use as an effective battery-type electrode in HSCs. With the multifunctional features, the rationally combined core-shell-like CoM NS@CoP/NF electrode exhibited a maximum capacity of 886.8 μA h/cm<SUP>2</SUP> at a current density of 5 mA/cm<SUP>2</SUP> with a good rate capability of 64.2% and cycling stability of 87.4% (after 10 000 cycles). The high electrochemical performance of the hybrid composite could be attributed to the synergistic effects of hierarchical architectures and large accessible electroactive area, which facilitates the fast electron/transportation within the active material and accelerates the redox chemistry process. Utilizing the superior energy-storage properties, a pouch-type HSC was fabricated with core-shell-like CoM NS@CoP-6 h architectures as a battery-type electrode and activated carbon as a capacitive-type electrode in an aqueous alkaline electrolyte. The miniature hybrid device exhibited maximum energy and power densities of 0.44 mW h/cm<SUP>2</SUP> and 40.35 mW/cm<SUP>2</SUP>, respectively, with good cycling stability. Moreover, the HSCs can energize various portable electronic equipments, which demonstrates their suitability for real-time applications.</P> [FIG OMISSION]</BR>
Bhagwan, Jai,Nagaraju, Goli,Ramulu, Bhimanaboina,Yu, Jae Su Electrochemical Society 2019 Journal of the Electrochemical Society Vol.166 No.2
<P>ZnCo<SUB>2</SUB>O<SUB>4</SUB> (ZCO) hexagonal nanoplates were synthesized by a facile, robust and cost-effective co-precipitation method. The as-synthesized nanoplates were utilized as an electrode material and their electrochemical properties were investigated in three-electrode and two-electrode configurations with aqueous electrolyte of 1 M KOH. The fabricated ZCO electrode materials exhibited a specific capacity of 37 mAh g<SUP>−1</SUP> at 1 A g<SUP>−1</SUP>. The capacity of the pristine ZCO nanoplates was further improved by incorporating multiwall carbon nanotubes (MWCNTs). The MWCNT@ZCO showed a specific capacity of 64 mAh g<SUP>−1</SUP> at 1 A g<SUP>−1</SUP>. To examine practical performances, asymmetric supercapacitor (ASC) was also fabricated using MWCNT@ZCO as a positive electrode and activated carbon as a negative electrode. The specific capacity of the ASC was found to be 17 mAh g<SUP>−1</SUP> at 0.38 A g<SUP>−1</SUP>. ASC could store sufficient energy to power a parallel combination of two red color light-emitting diodes. These findings may open new opportunities for the design of effective, stable, and easily recyclable ZCO electrode material for energy storage devices.</P>
슈퍼 커패시터 전극 응용을 위한 탄소섬유에 통합된 삼중 금속 산화물 나노입자의 바인더 없는 성장 및 특성
Shaik Junied Arbaz,S. Chandra Sekhar,Bhimanaboina Ramulu,유재수 한국진공학회 2021 한국진공학회 학술발표회초록집 Vol.2021 No.2
최근, 에너지 저장소자로 슈퍼커패시터에 대한 관심이 증가하고 있다. 본 발표에서는 바인더 없는 방법, 즉 직접 성장방법을 통해 슈퍼커패시터의 전극으로 삼금속 산화물 나노입자 통합 탄소섬유를 제작하였다. 구조적 구성에서 각 요소의 기여와 나노입자의 전기화학적 반응에 대한 연구가 이루어졌기 때문에 우수한 성능 특성을 가진 샘플을 최적화했다. 최적화된 샘플은 다른 합성 샘플에 비해 CV 특성에서 높은 전류응답, GCD특성에서 긴 방전시간 및 높은 커패시턴스 값을 나타냈다. 또한 최적화된 샘플의 지속 가능성 신뢰성 및 내구성은 전극이 여러번의 충전 및 방전 사이클을 거치게 함으로써 사이클링 프로세스를 통해 연구되었다.
Sekhar, S. Chandra,Nagaraju, Goli,Ramulu, Bhimanaboina,Yu, Jae Su American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.43
<P>We facilely prepared silver nanoparticle-decorated Ce<SUB>6</SUB>Mo<SUB>10</SUB>O<SUB>39</SUB> marigold flower-like structures (Ag NPs@CM MFs) for use as an effective positive material in hybrid supercapacitors (HSCs). With the aid of ethylenediaminetetraacetic acid (EDTA) as a chelating agent, self-assembled CM MFs were synthesized by a single-step hydrothermal method. When the electrochemical properties were tested in an aqueous alkaline electrolyte, the synthesized CM MFs with 0.15 g of EDTA exhibited a relatively high charge storage property (55.3 μA h/cm<SUP>2</SUP> at 2 mA/cm<SUP>2</SUP>) with a battery-type redox behavior. The high capacity performance is mainly because of the large surface area of the CM MFs, and the hierarchically connected nanoflakes provide wide open wells for rapid accessibility of electrolyte ions and enable fast transportation of electrons. A further improvement in electrochemical performance was achieved (62 μA h/cm<SUP>2</SUP> at 2 mA/cm<SUP>2</SUP>) by decorating Ag NPs on the surface of the CM MFs (i.e., Ag NPs@CM MFs), which is attributed to the increased electric conductivity. Considering the synergistic effect and the high electrochemical activity, Ag NPs@CM MFs were further employed as an effective positive electrode for the fabrication of pouch-type HSC with porous carbon (negative electrode) in an alkaline electrolyte. The HSC exhibited a high cell potential (1.5 V) with maximum energy and power densities of 0.0183 mW h/cm<SUP>2</SUP> and 10.237 mW/cm<SUP>2</SUP>, respectively. The potency of HSC in practical applications was also demonstrated by energizing red and yellow light-emitting diodes as well as a three-point pattern torch light.</P> [FIG OMISSION]</BR>