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현종찬,하손,강동혁,이은지,윤영수 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.1
In this study, waste pinecone-derived hierarchically porous pyropolymers (WP-HPPs) were fabricated from natural polymer precursors through simple heating process, and their specific surface areas and pore structures were tuned through a chemical activation process. The unique materials properties of WP-HPPs possessing high effective surface areas and hierarchically open nanopores led to high specific capacities of ~412 mAh g<sup>-1</sup> and considerable rate/cycling performances as a cathode for lithium ion batteries. In addition, when the WP-HPPs based cathode was assembled with a pseudocapacitive pyropolymer counterpart, the pseudocapacitive electrode pair exhibited high specific energy of ~340 Wh kg<sup>-1</sup> and a high specific power of ~11,000 W kg<sup>-1</sup> with long cycling stability over 2000 galvanostatic charge/discharge cycles. These results provide us an insight that natural polymers can be a useful electrode material through exquisite pyrolysis and activation process.
Microporous waste charcoals for redox-mediated supercapacitors
현종찬,곽진환,윤영수 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.79 No.-
The energy density of supercapacitors could be improved significantly using microporous carbon-basedmaterials (MP-CMs) with multitudinous redox-active heteroatoms through the hybrid charge storagebehaviors of both pseudocapacitance and electrochemical double layer capacitance in a redox-mediatedaqueous electrolyte system. Waste-derived MP-CMs were prepared using a simple activation process andused as high-performance electrode materials for redox-mediated supercapacitors, showing a highspecific capacitance of~512 F g 1 and a reasonable rate and cycling performance.
현종찬(Jong Chan Hyun),최연화(Yeonhua Choi),윤영수(Young Soo Yun) 한국세라믹학회 2022 세라미스트 Vol.25 No.1
Carbon materials have large numbers of redox-active sites for alkali-ion storage, such as Stone-Wales, vacancy, edge, and pseudo-edge defect sites as well as extrinsic defects. The topological defects can be a redox host in anodic voltage regions, while the extrinsic defects can store alkali ions in a cathodic voltage range. Therefore, carbon materials can be a great candidate for both anode and cathode for alkali ion batteries. In this study, alkali ion storage behaviors of different carbon materials, highly defective graphene-based nanosheet (GNS), well-ordered graphite nanoplate (GNP), hard carbon series samples, and nanoporous pyropolymers which are a kind of carbon materials including numerous defects, are reviewed, and their potentials as both anode and cathode for alkali ion batteries are discussed.
곽진환,현종찬,박재호,정경윤,유승호,윤영수,임희대 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.96 No.-
As promising candidates for next-generation batteries, calcium-ion batteries (CIBs) have attractedsignificant attention because of the lower cost and improved environmental friendliness of Ca metalrelative to those of Li and their potential to deliver higher energy densities. However, their practicalapplication has been limited by the lack of an appropriate electrode that can induce fast Ca cointercalation/deintercalation reactions while providing longer cycle life. In this study, we report bacterialcellulose (BC) with a highly graphitic-like ordered structure as a new and efficient co-intercalation hostfor multivalent Ca ions. The free-standing BC electrode with unique 3D porous morphology possessedultra-fast co-intercalation kinetics, much faster than that for a commercial graphite electrode. Inaddition, we addressed the controversial issue of whether Ca co-intercalation truly occurs in the graphiticlayer. It is demonstrated that the co-intercalation is directly dependent on the degree of carboncrystallinity by using various BC electrodes with different crystallinities at regular intervals. Finally, theeffect of the ordering of the carbon stacking layer on the co-intercalation chemistry waselectrochemically investigated.
Waste Sawdust-Derived Nanoporous Carbon as a Positive Electrode for Lithium-Ion Storage
곽진환,현종찬,문성박,진형준,임희대,윤영수 한국고분자학회 2020 Macromolecular Research Vol.28 No.13
Sustainable resources, particularly those induced from bio-derived waste materials, can be transformed into useful nanocarbon materials with high functionality. In this study, nanoporous carbon materials (N-CMs) were fabricated from waste sawdust using a simple heating process and a carefully controlled activation process. The waste-induced N-CMs had a high specific surface area of ~3044.6 m2 g-1, a nanoporous structure, and > 6 at.% heteroatoms. These properties led to high electrochemical performance with a specific capacity of ~298 mAh g-1 and excellent cycling stability over 2,000 cycles as a cathode in lithium-ion storage. Moreover, when the N-CMs were assembled with a nanostructured carbon-based anode, all full carbon- based cells could deliver high specific energy and specific power of ~377 Wh kg-1 and ~20,247 W kg-1, respectively, with a long-term cycle life of more than 1,000 cycles.
하손,현종찬,정예빈,최연화,윤영수 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.1
In this study, we propose a hierarchically nanoporous 3D assembly (HNA) composed of functionalized onion-like graphitic carbon building blocks, several nanometers in diameter, as a catalytic scaffold for Li-metal storage. The HNA-based electrodes can lead to a high Li ion concentration in the nanoporous structure by ion-exchange mechanism, showing a high CE of ~99.1%, high rate capability of 12 mA cm<sup>-2</sup>, and a stable cycling behavior of more than 750 cycles. In addition, anode minimized LMBs were achieved using the HNA that has limited Li content (~0.13 mg cm<sup>-2</sup>), corresponding to 6.5% of the cathode material (commercial NCM622 (~2 mg cm<sup>-2</sup>)). The LMBs demonstrated a feasible electrochemical performance with high energy and power densities of ~510 W h kg electrode<sup>-1</sup> and ~2760 W kg electrode<sup>-1</sup>, respectively, for more than 100 cycles.