본 논문은 전도성 고분자인 폴리피롤(PPy, polypyrrole)과 피트산(PA, pytic acid)을 이용하여 가교결합을 유도하고 이를 한지에 코팅하여 한지 기반 전도성 복합체를 제조하여 광열 효과와 오일 흡수 및 에너지 분야에 적용한 것에 관한 것이다. 첫 번째로는 한지인 한국 전통 종이를 개질하여 사용하였으며, 전도성 고분자인 폴리피롤을 사용하여 한지에 코팅하였다. 산화제 존재 하에 ...
본 논문은 전도성 고분자인 폴리피롤(PPy, polypyrrole)과 피트산(PA, pytic acid)을 이용하여 가교결합을 유도하고 이를 한지에 코팅하여 한지 기반 전도성 복합체를 제조하여 광열 효과와 오일 흡수 및 에너지 분야에 적용한 것에 관한 것이다. 첫 번째로는 한지인 한국 전통 종이를 개질하여 사용하였으며, 전도성 고분자인 폴리피롤을 사용하여 한지에 코팅하였다. 산화제 존재 하에 피롤단량체를 단순 중합하여 PPy 코팅하였다. 코팅된 PPy 네트워크는 PA를 사용하여 추가로 가교하였다. PA가 없는 샘플에 비해 PA에 의한 가교로 인해 전기 전도도가 최대 10 배까지 증가했다. 또한 PPy는 근적외선 흡수제이므로 NIR 하에서 발열 효과를 유도한다. 이와 같이 합성한 한지 복합체를 이용하여 광열효과를 알아보았다. PA를 함유한 한지 복합체의 성능이 우수한 결과는 PA와의 수소 결합에 의해 유지되는 PPy 사슬의 효과적인 가교 효과 때문이다. 두 번째 연구에서는 오일 / 물 흡수도 및 에너지 저장 성능을 위해 PA가 가교된 PPy 코팅 한지 멤브레인이 사용되었다. 개질된 멤브레인은 물과 기름의 혼합물에서 기름의 선택적 흡수를 보여 주었으며, 또한 전형적인 슈도 커패시턴스 타입의 저장 성능을 보여주었다. 세 번째 연구에서는 전력 밀도와 에너지 밀도가 우수한 슈퍼 커패시터(supercapacitor)에 이용하기 위해서 음극과 양극을 동시에 같은 소재를 이용하고자 하는 연구를 행하였다. 본 연구를 위해 CNT(carbon nanotube)가 결합된 vanadium phosphate 나노입자가 포함된 탄소나노섬유매트릭스를 제조하여 음극과 양극으로 활용하여 슈퍼캐퍼시터에 적용하였다. 0.66 A gￚ1의 전류 밀도에서 576.1 F gￚ1의 가장 높은 정전 용량을 나타냈으며, 5000회 사이클 후 최대 99 %의 뛰어난 안정성을 보였다. 이는 외장재인 CNT에 의한 내부 코팅 때문이었다. 또한 흥미롭게도 제조된 소재는 -1.2에서 0.6까지의 넓은 전위 범위에서 작용하여 대칭형 슈퍼 커패시터 장치 (SSCD: symmetric supercapacitor device)를 조립할 수 있는 기회를 제공했다. SSCD는 5000회 사이클 후 90 %의 안정성과 3.2 kW h의 전력 밀도에서 69.1 W h kg-1의 매우 높은 에너지 밀도를 보여주었다. 따라서 본 연구에서는 초고 에너지 밀도를 갖는 대칭형 슈퍼 커패시터 음극 소재용 새로운 복합재를 제조하기 위한 전략을 제시한다.
본 논문은 전도성 고분자인 폴리피롤(PPy, polypyrrole)과 피트산(PA, pytic acid)을 이용하여 가교결합을 유도하고 이를 한지에 코팅하여 한지 기반 전도성 복합체를 제조하여 광열 효과와 오일 흡수 및 에너지 분야에 적용한 것에 관한 것이다. 첫 번째로는 한지인 한국 전통 종이를 개질하여 사용하였으며, 전도성 고분자인 폴리피롤을 사용하여 한지에 코팅하였다. 산화제 존재 하에 피롤 단량체를 단순 중합하여 PPy 코팅하였다. 코팅된 PPy 네트워크는 PA를 사용하여 추가로 가교하였다. PA가 없는 샘플에 비해 PA에 의한 가교로 인해 전기 전도도가 최대 10 배까지 증가했다. 또한 PPy는 근적외선 흡수제이므로 NIR 하에서 발열 효과를 유도한다. 이와 같이 합성한 한지 복합체를 이용하여 광열효과를 알아보았다. PA를 함유한 한지 복합체의 성능이 우수한 결과는 PA와의 수소 결합에 의해 유지되는 PPy 사슬의 효과적인 가교 효과 때문이다. 두 번째 연구에서는 오일 / 물 흡수도 및 에너지 저장 성능을 위해 PA가 가교된 PPy 코팅 한지 멤브레인이 사용되었다. 개질된 멤브레인은 물과 기름의 혼합물에서 기름의 선택적 흡수를 보여 주었으며, 또한 전형적인 슈도 커패시턴스 타입의 저장 성능을 보여주었다. 세 번째 연구에서는 전력 밀도와 에너지 밀도가 우수한 슈퍼 커패시터(supercapacitor)에 이용하기 위해서 음극과 양극을 동시에 같은 소재를 이용하고자 하는 연구를 행하였다. 본 연구를 위해 CNT(carbon nanotube)가 결합된 vanadium phosphate 나노입자가 포함된 탄소나노섬유 매트릭스를 제조하여 음극과 양극으로 활용하여 슈퍼캐퍼시터에 적용하였다. 0.66 A gￚ1의 전류 밀도에서 576.1 F gￚ1의 가장 높은 정전 용량을 나타냈으며, 5000회 사이클 후 최대 99 %의 뛰어난 안정성을 보였다. 이는 외장재인 CNT에 의한 내부 코팅 때문이었다. 또한 흥미롭게도 제조된 소재는 -1.2에서 0.6까지의 넓은 전위 범위에서 작용하여 대칭형 슈퍼 커패시터 장치 (SSCD: symmetric supercapacitor device)를 조립할 수 있는 기회를 제공했다. SSCD는 5000회 사이클 후 90 %의 안정성과 3.2 kW h의 전력 밀도에서 69.1 W h kg-1의 매우 높은 에너지 밀도를 보여주었다. 따라서 본 연구에서는 초고 에너지 밀도를 갖는 대칭형 슈퍼 커패시터 음극 소재용 새로운 복합재를 제조하기 위한 전략을 제시한다.
The development of advanced and intelligent nanofibrous platforms with proper composition holds a great challenge. Other preferential criteria are the easy configuration, cost-effectiveness and uses of readily available green source materials. There is an urgent need for the green source-based mater...
The development of advanced and intelligent nanofibrous platforms with proper composition holds a great challenge. Other preferential criteria are the easy configuration, cost-effectiveness and uses of readily available green source materials. There is an urgent need for the green source-based material composite. The increasing possibilities of reusability and low cost, fibrous membranes have been considered as promising materials in different applications. The fibrous structure such as sponges, films with high porosity, surface area, conductivity and mechanical properties are the choice to be used for general applications. Herein, this thesis work is moistly focused on the development of intelligent membraneous structure for different applications. The first work is focused on the membranes prepared from the green product with superior mechanical property and electrical conductivity. The traditional Korean paper called Hanji was used with modification. The polypyrrole (PPy), a conducting polymer was used to coat the Hanji. PPy coating was obtained by the simple polymerization of pyrrole monomer in presence of oxidizing agent. The as-coated PPy network was further crosslinked using the phytic acid (PA). The products were characterized by physicochemically. The electrical conductivity was increased up to 10-folds up on the crosslinking by PA than compared to the sample without PA. Moreover, PPy is near-infrared light absorbing agent, therefore it induces the heating effect under the NIR. Thus as-coated membrane was used as the photo thermal study. The improved performance of the PA-containing membrane was attributed to the effective crosslinking effect of the PPy chains held by the hydrogen bonding with the PA. Thus, this study presents the strategy of the increasing thermal, electrical stability of the conductive polymer-based membranes which can be applied in various research areas such as sensing, energy storage, metal adsorption, and so on. In the second work, PA crosslinked PPy coated Hanji membranes were used for oil/water absorption and energy storage performance. The modified membranes showed selective absorption of oil from the mixture of oil and water. Also, it shows the typical pseudocapacitance type storage behavior. In third work, carbon nanotube (CNT)-protected vanadium phosphate nanoparticles trapped within an electrospun carbon matrix (CNTs@VPO@CNFs) was fabricated as the potential negative electrodes in energy storage application. Designing a novel composite material with hierarchical nanostructures as a negative electrode material with high capacitance and outstanding stability is challenging. Supercapacitors are among the most efficient energy storage devices due to their high power density, fast charge discharging process and high stability. However, the low energy density of supercapacitors compared to battery materials limits their use. To make a device with high performance, it is necessary to have both a negative and positive electrode, each with a high capacitance that can work across a wide potential range. Several works have reported the development of positive electrode materials with high capacitances. The development of negative electrode materials with high capacitance, conductivity and stability has been less studied. The development of a reliable negative electrode material with high performance for use in a high energy density supercapacitor should be considered for the development of future energy applications. Temperature was found to be the major controlling factor for the fabrication of composites with CNT decoration. CNTs@VPO@CNFs exhibited the highest capacitance of 576.1 F gￚ1 at a current density of 0.66 A gￚ1 among other corresponding electrode materials. Furthermore, this electrode exhibited outstanding stability of up to 99% after 5000 cycles, which was attributed to the internal coating by the CNTs as the sheath material. Interestingly, the as-fabricated material worked in a wide potential range from -1.2 to 0.6, thereby providing the opportunity to assemble a symmetric supercapacitor device (SSCD). The SSCD showed an exceptionally high energy density of 69.1 W h kg-1 at a power density of 3.2 kW h and 90% stability after 5000 cycles. Thus, this work presents a strategy for fabricating a new composite as a negative electrode material that can be used in a symmetrical supercapacitor device with an ultrahigh energy density.
The development of advanced and intelligent nanofibrous platforms with proper composition holds a great challenge. Other preferential criteria are the easy configuration, cost-effectiveness and uses of readily available green source materials. There is an urgent need for the green source-based material composite. The increasing possibilities of reusability and low cost, fibrous membranes have been considered as promising materials in different applications. The fibrous structure such as sponges, films with high porosity, surface area, conductivity and mechanical properties are the choice to be used for general applications. Herein, this thesis work is moistly focused on the development of intelligent membraneous structure for different applications. The first work is focused on the membranes prepared from the green product with superior mechanical property and electrical conductivity. The traditional Korean paper called Hanji was used with modification. The polypyrrole (PPy), a conducting polymer was used to coat the Hanji. PPy coating was obtained by the simple polymerization of pyrrole monomer in presence of oxidizing agent. The as-coated PPy network was further crosslinked using the phytic acid (PA). The products were characterized by physicochemically. The electrical conductivity was increased up to 10-folds up on the crosslinking by PA than compared to the sample without PA. Moreover, PPy is near-infrared light absorbing agent, therefore it induces the heating effect under the NIR. Thus as-coated membrane was used as the photo thermal study. The improved performance of the PA-containing membrane was attributed to the effective crosslinking effect of the PPy chains held by the hydrogen bonding with the PA. Thus, this study presents the strategy of the increasing thermal, electrical stability of the conductive polymer-based membranes which can be applied in various research areas such as sensing, energy storage, metal adsorption, and so on. In the second work, PA crosslinked PPy coated Hanji membranes were used for oil/water absorption and energy storage performance. The modified membranes showed selective absorption of oil from the mixture of oil and water. Also, it shows the typical pseudocapacitance type storage behavior. In third work, carbon nanotube (CNT)-protected vanadium phosphate nanoparticles trapped within an electrospun carbon matrix (CNTs@VPO@CNFs) was fabricated as the potential negative electrodes in energy storage application. Designing a novel composite material with hierarchical nanostructures as a negative electrode material with high capacitance and outstanding stability is challenging. Supercapacitors are among the most efficient energy storage devices due to their high power density, fast charge discharging process and high stability. However, the low energy density of supercapacitors compared to battery materials limits their use. To make a device with high performance, it is necessary to have both a negative and positive electrode, each with a high capacitance that can work across a wide potential range. Several works have reported the development of positive electrode materials with high capacitances. The development of negative electrode materials with high capacitance, conductivity and stability has been less studied. The development of a reliable negative electrode material with high performance for use in a high energy density supercapacitor should be considered for the development of future energy applications. Temperature was found to be the major controlling factor for the fabrication of composites with CNT decoration. CNTs@VPO@CNFs exhibited the highest capacitance of 576.1 F gￚ1 at a current density of 0.66 A gￚ1 among other corresponding electrode materials. Furthermore, this electrode exhibited outstanding stability of up to 99% after 5000 cycles, which was attributed to the internal coating by the CNTs as the sheath material. Interestingly, the as-fabricated material worked in a wide potential range from -1.2 to 0.6, thereby providing the opportunity to assemble a symmetric supercapacitor device (SSCD). The SSCD showed an exceptionally high energy density of 69.1 W h kg-1 at a power density of 3.2 kW h and 90% stability after 5000 cycles. Thus, this work presents a strategy for fabricating a new composite as a negative electrode material that can be used in a symmetrical supercapacitor device with an ultrahigh energy density.
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