https://scholar.dgist.ac.kr/handle/20.500.11750/10159 2026-04-04T10:35:43Z https://scholar.dgist.ac.kr/handle/20.500.11750/59956 Title: Tailored interfacial design via in situ polymer integration enhances thermoelectric performance in Bi2Te3 Author(s): Kim, Cham; Lee, Changwoo; Kim, Hyun-Sik; Lopez, David Humberto Abstract: This study introduces a distinct interfacial engineering strategy based on in situ polymer integration, which provides an effective and controllable route for modulating charge and heat transport for the development of a high-performance thermoelectric material. A thermoelectric composite was fabricated via a reproducible one-pot chemical process, in which the conductive polymer was polymerized and simultaneously deposited onto Bi2Te3. This approach yielded finely dispersed polymer domains with minimized agglomeration, resulting in increased interfacial contact with Bi2Te3. These interfacial contacts promoted energy filtering, inducing energy-dependent carrier scattering and a clear decoupling between electrical resistivity and Seebeck coefficient. The composite also exhibited suppressed thermal conductivity, attributed to enhanced phonon and carrier scattering at the interfacial contacts. These transport behaviors were confirmed by systematic experimental characterization together with complementary theoretical modeling based on the single parabolic band approximation. The composite achieved a maximum ZT of similar to 1.31 at 477 K and an average ZT of similar to 1.15 over the temperature range of 300-550 K. In comparison to other low-temperature n-type thermoelectric materials, the composite offers not only excellent thermoelectric performance but also advantages in cost, processability, and flexible device compatibility, making it highly suitable for practical and scalable thermoelectric applications. 2026-01-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/59910 Title: Tunable Hydrogen Dynamics Under Electrical Bias for Neuromorphic Memory Applications Author(s): Noh, Hee Yeon; Lee, Chan-Kang; Haripriya, Gopalakrishnan Nair Ramani; Lee, Shinbuhm; Lee, Myoung-Jae; Wee, Jiyong; Lee, Hyeon-Jun Abstract: A wide variety of materials and device architectures have been explored for memristor applications targeting neural network simulations, most of which rely on oxide-based structures that exhibit resistive switching driven by oxygen-vacancy-mediated memory effects. In this study, we present a novel approach for modulating resistive and nonvolatile memory behavior in oxide semiconductors through the controlled injection and extraction of hydrogen. The proposed two-terminal device incorporates a hydrogen source layer that facilitates the diffusion of hydrogen ions into the active oxide matrix, where they form hydroxide (OH) bonds and locally modulate the electron concentration. This process induces a stable and reversible memory effect under an applied electric field. Hydrogen exchange predominantly occurs at the interface between the active and insulating layers, with the latter serving as a buffer to maintain an optimal hydrogen concentration. Furthermore, neural network simulations were performed by utilizing the synaptic characteristics controlled via hydrogen modulation, achieving a recognition accuracy of 97.2% on the MNIST data set. The effects of input data resolution and weight quantization on recognition performance were also systematically investigated and discussed. 2026-01-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/59874 Title: Fabrication and evaluation of high-performance cylindrical supercapacitors using double-layered Ni-based electrodes Author(s): Lee, Damin; Kim, Dong Hwan; Roh, Jong Wook; Chung, Seok-Hwan; Kim, Jeongmin Abstract: Cylindrical supercapacitors were fabricated using Ni2(CO3)(OH)2-based transition metal electrodes synthesized via a hydrothermal method, and the electrochemical performances of single-layer and double-layer electrode configurations were systematically compared. Both devices were designed to maintain the same total electrode area, with a graphite anode inserted at the core to ensure stable electron transport and mechanical robustness. Electrochemical evaluations revealed that the single-electrode device exhibited a specific capacity of 112.4 mAh g−1 at a current density of 2 A g−1, while the double-layered device showed 101.7 mAh g−1 under the same conditions. Moreover, the single-layer electrode delivered an energy density of 30.4 Wh kg−1 and a power density of 406.4 W kg−1, whereas the double-layered electrode achieved improved values of 49.3 Wh kg−1 and 548.3 W kg−1, respectively. These results demonstrate that the cylindrical structure fabricated by rolling double-layered electrodes effectively mimics the architecture of commercial energy storage systems, providing a practical approach for evaluating real-world applicability. 2026-02-28T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/59396 Title: 자기장 이용 전극활물질 결정배향을 통한 리튬이차전지 성능 향상: 자기특성 이론해석 및 자기장 감축기술 연구 Author(s): 김참 Abstract: 리튬이차전지 상용 전극활물질(LiNixMnyCo1-(x+y)O2)의 자기특성에 기반한 자기장 이용 결정배향 연구를 통해 활물질 내 결정의 리튬이온 전달방향을 전극집전체 표면에 수직으로 배향하는 기술을 개발하였다. 상용 양극활물질의 자기특성 측정 및 분석을 통해 결정배향에 필요한 자기장 크기를 이론적으로 고찰하였고, 일반 전자석에서 조성 가능한 수준의 자기장(ca. 1 Tesla (T)) 을 이용한 결정배향 기술을 확보하였다. 해당 기술은 강자기장(3 T)을 이용한 본 연구그룹의 선행기술 대비 유사한 활물질 결정 배향성 및 전기화학적 성능 향상도를 보였다. 낮은 자기장을 이용한 결정배향 기술의 유효성을 이론적, 실험적으로 검증함으로써 관련 기술의 산업적용 가능성을 제고하였다. Based on the magnetic properties of commercial cathode material (LiNixMnyCo1-(x+y)O2) for lithium-ion batteries, we have developed a technique utilizing magnetic fields to orient crystal structures, aligning the lithium-ion transfer direction perpendicular to the electrode surface across the entire electrode assembly. Through measurements and analysis of the magnetic properties of the commercial cathode material, we theoretically examined the required magnetic field strength for crystal orientation and secured a technique for crystal orientation using magnetic fields achievable in conventional electromagnets (approximately 1 Tesla (T)). This technique demonstrated comparable crystal orientation and electrochemical performance enhancement to the previous technology developed by our research group using strong magnetic fields (3 T). By validating the effectiveness of crystal orientation of commercial cathode materials at lower magnetic fields theoretically and experimentally, we aim to enhance the industrial applicability of related technologies. 2025-09-30T15:00:00Z