https://scholar.dgist.ac.kr/handle/20.500.11750/213 Sat, 04 Apr 2026 20:53:53 GMT 2026-04-04T20:53:53Z https://scholar.dgist.ac.kr/handle/20.500.11750/60001 Title: Proton-dominant charge storage in layered H2V3O8 for Mn2+/H+ hybrid aqueous batteries Author(s): Pyun, Jangwook; lee, Hyeonjun; Lee, Yeon-U; Lee, Sangki; Hong, Seung-Tae; Aurbach, Doron; Chae, Munseok S. Abstract: Aqueous rechargeable batteries (ARBs) are compelling for grid‑scale storage owing to their cost effectiveness, promising safety features, and sustainability. Within this landscape, Mn‑based batteries offer a deeper redox potential (−1.19 V vs. SHE), high theoretical energy density, abundance, and low toxicity. However, the large hydrated radius and strong electrostatic interactions of Mn²⁺ in water severely hinder bulk intercalation and, thus, reversible capacity. Here we demonstrate a Mn²⁺/H⁺ hybrid chemistry using layered H₂V₃O₈ as the cathode host. These electrodes may deliver high specific capacity > 320 mAh g⁻¹ at 0.2 A g⁻¹ and may retain around 70 % of their initial capacity after 3500 cycles. Comprehensive spectroscopic and structural analyses revealed that Mn²⁺ mainly forms surface by‑products and functions as a secondary charge carrier, whereas protons dominate the charge compensation. This dual‑ion mechanism underpins the high capacity, fast kinetics, and durable cycling. Mn metal//H₂V₃O₈ full cells can operate at 1.23 V, benefiting from the large electrodes’ potential gap, and exhibits robust electrochemical performance. Our results clarify the interplay between Mn²⁺ and H⁺ in aqueous media and position H₂V₃O₈ as a promising cathode platform for next‑generation, safe, and sustainable energy storage devices. Wed, 31 Dec 2025 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/60001 2025-12-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/59982 Title: Engineering Hollow-Structured Carbon Framework to Facilitate High-Sulfur-Content Encapsulation for Lithium-Sulfur Batteries Author(s): Sung, Jong Hun; Lee, Soyun; Yu, Jeong-Hoon; Lee, Jiwon; Yu, Bo; 이동현; Lee, Ha-Young; Hong, Seung-Tae; Ibnu Syafiq Imaduddin; Kang, Joonhee; Yu, Jong-Sung Abstract: Lithium-sulfur batteries (LSBs) have emerged as promising candidates for next-generation energy storage systems due to their high theoretical energy density and cost-effectiveness. However, their practical application is severely limited by the shuttle effect of lithium polysulfides (LiPSs) and the inherently low electrical conductivity of sulfur, which leads to rapid capacity fading and poor rate performance. To address these challenges, this work develops a hollow-structured graphitic nitrogen-doped porous carbon (h-GNPC) framework derived from zeolitic imidazolate framework-8 via a magnesiothermic reduction (MR) process. This method effectively tailors the pore architecture and electrical conductivity, enabling efficient sulfur encapsulation and high sulfur loading up to 90 wt.%. Compared to a carbon host treated without the MR method, the h-GNPC exhibits enhanced porosity, which can accommodate sulfur with stabilized cyclability. As a result, a coin cell with sulfur-loaded h-GNPC cathode exhibits an initial capacity of 1292.9 mAh g−1 and enhanced capacity retention of 74.9% over 500 cycles at 0.2C as well as rate performance. Notably, pouch-type cells assembled with the h-GNPC cathode demonstrate excellent scalability and cycling stability, highlighting the practical potential of this design for the commercialization of LSBs technology. Sun, 30 Nov 2025 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/59982 2025-11-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/59980 Title: High Performance Nonaqueous Ca-Ion Cathodes Based on NASICON-NaV2(PO4)3 and the Way to Activate Their Structure Author(s): Lee, Hyungjin; Pyun, Jangwook; Lee, Yeonu; Lee, Hyeonjun; Hong, Seung-Tae; Chae, Munseok S. Abstract: Calcium-ion batteries (CIBs) are gaining attention as a promising energy storage technology due to their high theoretical capacity, attributed to the divalency of calcium, low redox potential, and natural abundance. However, the limited availability of calcium insertion electrode materials and their tendency to exhibit low capacity or poor cyclability remain critical challenges. In this study, the activation mechanism underlying calcium ion storage in NASICON-type NaV2(PO4)3 structures are investigated using advanced structural analyses and elemental analyses. NaV2(PO4)3 is identified as an efficient cathode material for CIBs, demonstrating a reversible discharge capacity of 106.9 mAh g-1 at 10 mA g-1-an 82% improvement compared to the pristine material-while maintaining an average operating voltage of approximate to 3.5 V (vs Ca/Ca2+) and good cyclability in a nonaqueous electrolyte. These findings offer valuable insights into the design and development of advanced oxide-based cathodes, enhancing their performance through activation processes for nonaqueous CIBs. Sun, 30 Nov 2025 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/59980 2025-11-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/59978 Title: Unveiling the Crystal Structures of Na2SiS3 Polymorphs and Na6Si3OS8 as Sodium Ionic Conductors Author(s): Roh, Jihun; Bu, Hyeri; Kim, Hyojin; Kim, Hyungsub; Kim, Dokyung; Lee, Young Joo; Hong, Seung-Tae Abstract: All-solid-state Na-ion batteries are promising energy storage systems due to the abundance and cost-effectiveness of sodium resources. This study unveils three crystal structures of sodium ionic conductors via ab initio structure determination using powder X-ray and neutron diffraction data: two polymorphs of Na2SiS3 and Na6Si3OS8. The high-temperature (HT) Na2SiS3 polymorph crystallizes in the tetragonal space group of P4(2)/mcm and features isolated Si2S6 units consisting of two edge-sharing SiS2S2/2 tetrahedra. The low-temperature (LT) polymorph adopts the orthorhombic Pbca space group and contains infinite chains of corner-sharing SiS4 tetrahedra, where each tetrahedron shares two sulfur atoms with neighboring units. Na6Si3OS8 crystallizes in the monoclinic P2(1)/c space group and contains isolated Si3OS8 units comprising one corner-sharing SiS2S2/2 tetrahedron and two SiS2S1/2O1/2 tetrahedra linked via a bridging oxygen atom. HT-Na2SiS3 exhibits a sodium ionic conductivity of 1.85 x 10(-7) S cm(-1) at 303 K with an activation energy of 0.36 eV, while Na6Si3OS8 shows a lower conductivity of 1.10 x 10(-9) S cm(-1) and a higher activation energy of 0.43 eV. Bond valence energy landscape calculations revealed three-dimensional sodium-ion diffusion pathways in HT-Na2SiS3 and Na6Si3OS8, characterized by relatively low energy barriers. In contrast, the LT polymorph features more restricted pathways with higher diffusion barriers. These results provide valuable insights into the relationship between crystal structure and ion mobility, offering guidance for the design of next-generation sodium solid electrolytes. While this work establishes fundamental structure-property relationships, further studies are needed to assess their electrochemical performance in practical battery systems. Tue, 30 Sep 2025 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/59978 2025-09-30T15:00:00Z